Copepods in NYC Water: A Scientific and Halachic Background
June 2004, after hearing much discussion and reading about it in the national
media, many in the
technical information in this article is derived from a report commissioned by
the Orthodox Union on the question of the copepods in
What are copepods?
are aquatic crustaceans (they have an exoskeleton that covers their bodies)
that come in a number of varieties and are used frequently in scientific
research. They are the most prevalent
organisms found in most water reservoirs in the
There are three species of
copepods in the
Background on the
The two other water
systems are the Catskill and
Most of the city derives
its water from one of these two tunnels.
The types of aqueducts vary throughout the
system. Many are merely trenches in the
ground, lined with cement and covered by cement arches traveling in open areas
or through hills and mountains. Cement
lined steel pipes are used to complement areas where trenches are not
available. These systems do not fill
entirely with water during use. Pressure
tunnels (that entirely fill with water) are used to bypass valleys by
constructing vertical shafts and deep circular tunnels, lined by cement. One of the largest is a tunnel that crosses
All water leaving Kensico and Hillview reservoirs is chemically treated upon exit. Fluoride is added at approximately 1 part per million (ppm) to prevent tooth decay, chlorine is added to kill inhabiting zooplankton and meet disinfection requirements and orthophosphate is added to create a protective film on pipes to prevent lead contamination.
The issues are presented in a ‘pseudo-sequential’ order – that is, from the bottom up. The question of the status of the copepods in halacha, their source from the reservoirs and their function in various mixtures (ta’aruvot) will be discussed first. The need for filtration depends not only on whether the copepods present a valid halachic problem, but also on their frequency of occurrence and concentration at the faucet. It must be kept in mind that while there are poskim who argue that the copepods in fact should be prohibited – this may not have bearing on the need to filter. The criteria of concentration and frequency will be discussed at the end of this section. The Torah (va-Yikra 11: 9 – 13) explicitly forbids the consumption of creeping creatures without fins and scales (sheratzim), whether they live on land or in the sea. Unlike other prohibitions regarding food items (ma’akhalot assurot), the consumption of a sheretz entails the violation of four separate prohibitions, entailing four sets of punishments. The Gemara in Bava Metzi’a 61b even goes so far as to declare that yetzi’at Mitzrayim would have been worthwhile if its only result was Bnei Yisrael receiving the prohibition against forbidden sheratzim! It is therefore not taken lightly by the poskim and is cause for serious concern.
I. Creature Size in Halachic Criteria:
As noted above, the copepods in question range in size from 500 to 1,200 uM. They should not be defined as microscopic, as the average person, when looking closely can see objects larger than 40 uM. Actual identification of such small objects however, requires substantially larger sizes. Their lack of immediate visibility in a glass of water led many people to assume that they are indeed microscopic and therefore not halachically prohibited. The chlorination process intended to kill the copepods, leaves them as dead, translucent creatures that take a bit more time and focus to ascertain and distinguish. Identifying these creatures as such does indeed take some getting used to; those who have been doing so for longer can usually find them rather quickly. They are simplest to see in a pool of shallow water over a dark background. However, it must be noted that those ‘experts’ trained in identifying these creatures do not have special visual capabilities – they have merely learned how to look at water properly. Analogously, there are many creatures in the rainforests that are camouflaged and blend it quite well with their surroundings, such as butterflies and lizards. A cursory glance by an inexperienced eye will not detect these ‘hidden’ creatures. Such a novice can be trained however, to learn how to locate these animals. This novice did not need laser correction surgery, but rather a lesson in rainforest fauna. While almost anybody can be taught to find them in the water, the positive identification of copepods as creatures is far more difficult and most easily undertaken with the aid of a microscope.
b. Visible but not identifiable as a sheretz:
R. Shmuel Wozner discusses the status of similar creatures found on citrus fruits (where the creatures are visible but not identifiable as creatures). He claims that visibility alone does not entail prohibition; the creature must be identifiable as a creature to pose a problem. He argues that in such cases “it is not the person’s vision that brings about the prohibition, but rather the microscope [allowing for the creature identification].” This also seems to be the initial assumption of R. Shlomo Zalman Auerbach. R. Hershel Schachter noted that based on the Chazon Ish’s position regarding the history of halachic development there is further room to rule leniently. The Chazon Ish explained the Gemara’s declaration that the “world experienced 2000 years of Torah” to mean that all of halacha was established during that time period and that it can no longer change. R. Schachter argues that the halachic definition of vision was established then as well. Since during that time period these creatures were not identifiable as sheratzim (mechanical visual aids had not yet been perfected), our contemporary superior visual ability has no relevance as regards these creatures’ status; thus ingesting them should be permitted.
The Chazon Ish himself however, rejected such an idea. If something is visible and we know that it is a sheretz, then it is prohibited whether or not we can visually identify it as such. It is not a person’s vision that ‘causes’ the issur as R. Wozner claimed, but rather the fact that the object in question is in fact a sheretz that brings about the prohibition. R. Yehoshuah Neuwirth relates that upon hearing that the Chazon Ish had been stringent in this matter, R. Auerbach reversed his previous opinion and agreed to the Chazon Ish’s position. Furthermore, when news of this story broke in June 2004, R. Feivel Cohen relates that he asked R. Yosef Shalom Elyashiv about this specific matter and R. Elyashiv cited the Chazon Ish’s stance and ruled stringently. Furthermore, R. Elyashiv co-signed a pesak issued by R. Dovid Feinstein requiring filtration, further identifying himself with this approach.
c. Visibility when alive:
While the copepods are difficult but
nonetheless possible to locate when dead, when alive they present little
challenge. Water samples from the
reservoirs reveal creatures that can be seen swimming through the water in
seemingly random directions; it is quite clear that these specks are living
beings. Rashi in fact defines a sheretz
as a creature that is so small that it can only be detected by its movement. The Ben Avraham (50:42) adopts this
definition wholeheartedly and claims that whether or not such a creature is
identifiable as such after death – it is nonetheless prohibited based on its
definition as a sheretz when alive. He assumes that once a prohibited status is
applied to a creature during its lifetime it cannot be removed upon death. R. Hershel Schachter adopts this position and
argues that the copepods should be prohibited, since even though they are not
identifiable as creatures at this stage, they are nonetheless visible. R. Yisrael Belsky however, notes that the Ben
Avraham discusses a case in which the prohibited sheratzim are certainly
in the water. Since one cannot be certain that there are
indeed copepods in
d. Complete copepods versus exoskeletons:
However, it is important to note that not all of the copepods that appear at the faucet are intact; a small percentage are merely the exoskeletal remains with very little or no ‘insides’ remaining. Many poskim were unaware of this phenomenon and therefore did not respond to its ramifications. The halachot regarding sheratzim themselves are distinct from those governing the bones of sheratzim. Even if one concedes that the copepods are indeed prohibited, their bones and exoskeletons may not be. These halachot regarding the status of bones of sheratzim will be discussed later. It seems that something happens to these creatures during their tortuous travel that allows their muscles and viscera to disintegrate and seep out of their outer shell. It is unclear at this point what mechanism is responsible for this occurrence. Therefore, even if one were to see a speck in the water, one could not be certain that it is indeed an intact copepod; it may perhaps be only the molten exoskeleton or even dust. It would seem that in this situation the logic of the Ben Avraham does not apply. He assumes that all the unmoving specks are simply dead sheratzim that are indeed visible and identifiable when alive. However, it is simply not the case that every spec that appears in the tap water, to be a creature actually was a forbidden creature when alive – a certain percentage are merely the chitin exoskeletons.
e. Questions from the past:
Lastly, it should be noted that questions of insect infestation are not modern phenomena and were probably more frequently problematic in the past. Many poskim discuss the status of a certain creature known as a milbin often found in flour. Regardless of their conclusions pertaining to the specific question at hand, they all agree that milbin are prohibited creatures. R. Yitzhak Bistritsky cites Bedikat ha-Mazon ka-Halacha as claiming that milbin are smaller than 200uM - smaller than most of the copepods in question. It would seem therefore that all these poskim would argue that the copepods indeed present an issur de-oraitah. However, the identification of milbin as a specific species seems somewhat speculative. Many poskim from all over the world discuss the existence of these creatures and it seems highly unlikely that they all had the same specific creature in mind. It may be that the poskim simply used the term milbin to refer to crawling creatures found in flour and did not mean to identify a specific species. If so, it is highly likely that these milbin were significantly larger than the copepods in question, as it seems from the responsa literature that many people found them in their produce, in contrast to the copepods that hardly anybody noticed before June 2004.,
II. Where do they come from?
a. Sheratzim she-be-keilim:
The Mishnah in Chullin 66b expounding upon va-Yikra (11: 9 – 10) that discusses the halachot of permitted fish and explains that while fish require fins and scales to be deemed kosher, there are certain water sheratzim that are kosher even though sheratzim have neither fins or scales. The subsequent Gemara (citing Torat Kohanim ibid.) explains that these pesukim refer to sheratzim that reside in vessels (keilim) and rules that sheratzim that reside in pits, ditches and caves are kosher despite their lack of fins and scales, since the water in these containments derives from rainfall and melting snow (these water bodies have similar characteristics to water found in keilim). The Gemara continues to define two other bodies of water: yamim u-nehalim, seas and rivers, as well as haritzim ve-ne’itzim, canals and ducts. All sheratzim found in the former are prohibited. The water body classification of haritzim ve-ne’itzim is divided into two categories, nove’im and moshechim. Haritzim ve-ne’itzim ha-nove’im transport water from an underground water source or a spring; all poskim agree that sheratzim found therein are prohibited. Haritzim ve-ne’itzim ha-moshechim transport rain water or melted snow, whose flow changes with the seasons. The status of creatures found in these waters is subject to a dispute: Rambam (Ma’achalot Assurot ) prohibits ingesting them and Rosh (Chullin 9:68) permits. The Mechaber (84:2) cites the two positions by stating that “there are those who prohibit and those who permit” the ingestion of sheratzim found in haritzim ve-ne’itzim ha-moshechim without rendering a deciding opinion. Shach (84:8, as well as Pri Megadim ibid) argues that since the prohibition in question stems from the Torah, we must be strict; R. Dovid Feinstein cites these poskim as the norm. However, the Pitchei Teshuvah (84:1) notes that the Shu”t Mishkenot Ya’akov (YD 27) disagrees and argues that the correct approach is to follow the Rosh and permit ingesting these creatures. Moreover, there is a longstanding ‘rule’ that when the Shulchan Aruch presents two opinions in this manner (“some say … and some say …”), we always follow the latter opinion (the Rosh in this case who permits ingesting these specific sheratzim).
Before examining the various opinions regarding the reservoirs themselves, it should be emphasized that many scientific experts have agreed that the copepods breed exclusively in the reservoirs themselves and could not survive to germinate in the waters entering or exiting the reservoirs. Therefore the body of water in question is the reservoir, the copepods do not enter these waters from an outside source. Similarly, the only copepods found in the aqueduct system arise from the reservoirs as well, with no possible germination along the way.
b. Ha-yoztei min ha-tamei, tamei:
The Chazon Ish (YD 14:6) has an interesting position on the question of sheratzim she-be-keilim. He claims that the rules of permitted sheratzim cannot override the rules of ha-yoztei min ha-tamei, tamei – that which comes from an impure object is impure itself. Chazon Ish argues that any sheratzim that are the product of reproduction of a prohibited sheretz are also prohibited, regardless of where they were born, reside or germinate. Since today we know that all creatures are the products of reproduction and not spontaneous generation, it seems that all sheratzim, even those born in vessels, should be prohibited. Many poskim however, dismiss this assertion categorically. They ask that according to the Chazon Ish’s logic, what creatures fall under the rules of permitted sheratzim? There are no spontaneously generated creatures and therefore none meet these criteria and it is clear that the halacha intended to discuss real phenomena (at least in this case). However, it seems safe to assume that the Chazon Ish was aware of this problem and nonetheless thought the way he did – perhaps he had an answer to it that he did not record, or that the question simply did not bother him, we will never know. While it seems a rather weighty position to ignore, such has been its fate.
c. Ma’ayanot and comparison to hilchot mikva’ot:
Assuming the Chazon Ish’s position is indeed ignored, the major question facing the poskim is how the reservoirs fit into this picture. Various positions have been proposed spanning the entire spectrum of options. The seemingly simplest approach is to recognize that the rivers and creeks that feed the reservoirs stem from natural springs (ma’ayanot) and as such have the status of nehalim, with all sheratzim growing therein prohibited. With respect to this approach, R. Dovid Feinstein notes that the reservoirs should not be considered borot, cisterns (that have the same halachic status of keilim), since they have both an inlet and outlet. Second, R. Feinstein posits that although the movement of water within the reservoir cannot be perceived (only determined) and the great majority of the water seems immobile, nonetheless since it originates from springs and is destined to leave, it must qualify as yamim u-nehalim. In the context of mikva’ot as well, halacha differentiates between naturally occurring springs, ma’ayanot, and collected rainwater. Shu”t Mishkenot Ya’akov (YD 45) and others use parallel definitions of water bodies in both these areas, using the more elaborate and heavily discussed mikva’ot definitions and applying them to the rules of ingesting sheratzim. As in mikva’ot, the source of the water is one of the deciding factors in determining the status of a subsequent body of water, giving the reservoirs the status of ma’ayanot and prohibiting the copepods.
Although all springs ultimately derive their water from rainfall and melting snow absorbed by the mountain, transported via aquifers, collected and ultimately projected as a spring, halacha distinguishes between these two bodies of water. Shu”t Mishkenot Ya’akov (ibid) explains that once the water is absorbed by the mountain and transported some distance – it loses its definition as rainwater and is ‘reborn’ as a spring. The Netziv quantifies the distance that water must travel to be reborn as a spring as at least four amot, while the Tzemach Zedek (Lubavitch) requires a distance of at least 100 amot. Ramban (Bereishit 26:17) claims that this was the very disagreement between Yitzhak Avinu and the shepherds of Gerrar. Since the lion’s share of the reservoir contents derives from these sources, it would seem that all copepods residing within are forbidden.,
d. Sheratzim as components of the water:
R. Yitzhak Raitport argues and assumes that all sheratzim should take on the status of the substance from which they derive. He tries to prove this from the Gemara in Avodah Zarah 12b that explains that a person should not drink water from neharot (rivers) at night since there is a danger of swallowing leeches (that he may not be able to see without ample lighting). The obvious question is that a person should not drink from neharot at night since he might consume sheratzim – even those that are not dangerous! Why is prohibition merely explained as a safety feature and not as a problem of consuming forbidden sheratzim? Shu”t Maharam Shik (OH 134) explains that the Gemara in Avodah Zarah is referring only to rivers in which creatures are not prevalent and there is little or no possibility of ingesting any sheratzim. R. Raitport claims that it is unlikely that the Gemara in Chullin (that explains that sheratzim in keilim are permitted whereas those in neharot are forbidden) refers to neharot where creatures are prevalent while the Gemara in Avodah Zara refers to neharot without a significant creature population. He prefers to explain that there are two types of water sheratzim: those that are created from the water and those created from the land or air and that later migrated into the water; the former are permitted and the latter clearly prohibited. The only problem of water creatures in mayim ha-nove’im is that we suspect that they may have been created on (from) the land and migrated into the waters. He claims a parallel structure in Chullin 77b regarding sheratzim that grow on (from) animals and fish that have the same status of the animals and fish at that moment. Lastly, he argues that this logic is found in Shu”t Tzemach Tzedek (Lubavitch, YD 62) where he raised a separate possible leniency for some type of sheretz found in a river in Skver, but nonetheless concluded stringently, since he was concerned that the sheratzim were created on (from) the ground or air and later entered the water. R. Raitport contends that from this language, we can conclude that the Tzemach Tzedek would agree that if the sheratzim were created from the river itself they would be permitted, as per his previous contention.
This approach is rather novel and does not seem to have any precedent in the poskim. Secondly, it is unclear who is the ‘speaker’ at this point in the responsum of the Tzemach Tzedek. The text in question appears in the question segment (before the words “here ends the question”) but in parentheses, raising the possibility that it was the Tzemach Tzedek himself who added this possible leniency into the question. For this reason alone, it would not seem prudent to base leniencies on this logic. Lastly, it seems at best to be an attempt to provide a coherent logic behind a somewhat obscure Torah law – doresh ta’ama de-kera. The halacha however, follows R. Yehudah that we do not attempt to provide such reasoning, let alone use it as a basis for leniencies.
e. Non-mikva’ot definitions of water:
is an alternate approach to the notion that denies the continuous definition of
a ma’ayan from hilchot mikva’ot to hilchot tola’im
(insects). R. Yehoshuah ha-Kohen
that still waters collected in a cave should have the status of mayim
she-be-keilim even though water flows into this area from a natural
spring. Since the water is currently not
in a ma’ayan but rather in a collected reservoir, the halacha should
categorize all creatures within that water as arising from mayim
she-be-keilim, since the connection to the spring is irrelevant. In contrast, in hilchot mikva’ot the
source of the water and the manner in which it arrives at its final destination
are of utmost importance. R. Perachyah
further claims that since it is unlikely for flowing water to contain small
creatures, we can assume that they germinated and grew only in the collected
waters of the reservoir. The previously mentioned experts adamantly
reject the notion that the copepods in the
f. The status of sheratzim once they leave their original habitat (sheratzim she-pirshu):
Even if we assume that the waters in the reservoirs are of the type that spawn permitted sheratzim, the Gemara in Chullin (67b) explains that this permission applies only to these sheratzim in their original habitats. Once the sheratzim leave their original permitted habitat and enter a body of water whose inherent sheratzim are forbidden, the migrating sheratzim also become forbidden (a similar situation to sheratzim in produce). The Rashba explains that the original habitat is limited to the kli in which they germinate as well as its inner surfaces; migrating to the outer surface of that same kli renders them forbidden. Therefore, once the sheratzim leave one permitted water body, such as a bor, and enter a kli (where the sheratzim would be permitted to eat if they had originated and remained there) they are nonetheless forbidden. The Beit Yosef argues that a sheretz going from one kli to another should not create any difference in halachic status and the only change in status should arise when migrating between two different categories of water (such as from a bor to a kli).
g. The status of sheratzim in their new environment:
There is a three-way disagreement as to the status of the inside of the new kli. The Shach (84:4) claims that while the sheratzim are in the water of the kli, they are permitted. However, once they migrate to the walls of the vessel, kli, they become forbidden. The Taz (84:5) argues that the insides of the new kli are exactly parallel to the water inside the kli and therefore if the sheratzim migrate to the walls they are still permitted. The Issur ve-Heter (as understood by the Pri To’ar) argues that once the sheratzim enter the kli they are forbidden, whether or not they migrate anywhere. (The fact that these sheratzim are dead at this point will be discussed below.) Regarding an aqueduct leading from a bor to a kli (under an open faucet), R. Shmuel Wozner claims that the Issur ve-Heter will clearly prohibit and the Taz will permit all of the sheratzim. He explains that the Shach’s position would depend on whether or not the aqueduct is filled with water or whether there is space within the tube for the sheratzim to migrate to the sides of the walls. He posits that if the water reaches only half the vertical height of the aqueduct then we must be concerned that the sheratzim migrated onto the walls and the Shach would prohibit these sheratzim.
R. Hayim Oberlander points out however, that there is additional room for leniency in our case since almost all of the copepods are killed before they enter the aqueduct systems. The Rambam (Ma’achalot Assurot ) claims that postmortem ‘migration’ is considered regular migration and the sheratzim are therefore forbidden, while the Rosh (ibid 3:68) disagrees and concludes more leniently. The Mechaber (84:4) cites the Rosh as the standard opinion and mentions that “some say” (yesh omrim) to follow the Rambam. R. Oberlander argues that there are several reasons to conclude leniently in this matter. Firstly, there is a longstanding rule that when the Mechaber quotes one nameless opinion and the second opinion as yesh omrim, we always follow the former opinion. Moreover, in this case, the Shach (84:12) independently arrives at the lenient conclusion as well. Secondly, the impetus for stringency in the previous question is the position of the Shach. He himself however is of the opinion that postmortem migration is meaningless! Therefore, even if we are to follow the Shach’s strict approach above, it is not relevant to our case because of the Shach’s lenient opinion with regard to ingesting sheratzim that migrated postmortem. R. Oberlander notes however that the Minchat Ya’akov (46:13) and Pri Megadim conclude strictly in this latter issue (like the Rambam) and therefore there is little room for lenient maneuvering.
The application of
these regulations hinges upon the halachic definition of the reservoirs and the
aqueduct system. If both are considered keilim,
then there is no question of migration at all if we assume that the copepods
are considered sheratzim she-be-keilim and therefore permitted. If the reservoir is considered a bor
and the aqueducts considered keilim however, the status of the copepods
is subject to dispute between the Issur ve-Heter and the Taz. R. Yitzhak Raitport adopts the former
approach and contends that the reservoirs and the entire water delivery system,
including all aqueducts, tunnels, pipes and passages have the status of one
tremendous kli; thus, the copepods cannot be deemed to have migrated
from one category of water to another and accordingly, ingesting them should be
permitted. R. Yitzhak Bistrisky counters that this
assertion is simply fantastic that requires a large stretch of the imagination! On a more halachic plane, Shu”t Remet”z
(YD 30:5) argues that a kli
that is firmly attached to the ground (such as the aqueducts) receive the
status of the ground itself, giving the creatures inside this kli a
status of sheretz ha-aretz that are always prohibited regardless of
migration. Further consideration is needed regarding the
status of the water in
III. Bones of a sheretz:
As mentioned previously, experiments have shown that sometimes what at first appear to be copepods are in fact only the exoskeletal remains (‘ghosts’) of these creatures. The visual distinction between intact copepods and the ‘ghosts’ is rather nuanced and not readily appreciated by the novice. Torat Kohanim (Shemini 3:) explains that the bones and fins of sheratzim are not forbidden, unlike their fleshy substance, basar. Later, however, the Torat Kohanim expounds that a kelipat ha-sheretz is forbidden. The term kelipat ha-sheretz does not occur often in halacha and is somewhat ambiguous; normally kelipah means shell or peel (such as of a fruit). A likely physiological structure of sheratzim that fits this description seems to be the exoskeleton, which would render both intact copepods as well as their exoskeletal remains prohibited. As noted above, the poskim have generally not as of yet addressed this issue and will have to analyze this question as well.
Even if we assume that the exoskeleton qualifies as bones, it is not immediately apparent that it should be permitted. Although the question of sheratzim bones similarly does not occur frequently, a parallel question concerning eating bones of non-kosher animals does play prominently in halachic analysis. While the Torat Kohanim (ibid, 2:4:8) makes a similar permissive claim regarding the consumption of non-kosher animal bones, the Rambam (ibid ), as understood by R. Yehezkel Landau explains that they are nonetheless Rabbinically prohibited. R. Hayim Ozer Grodzinsky however, claims that this rabbinic prohibition applies only to soft bones containing marrow; hard, dried bones are entirely permitted. This permission flows from the Shibbolei ha-Leket’s (, quoted in Ramo YD 87:10) claim that a dried-out stomach of a cow loses its status as meat regarding prohibitions of mixing it with milk. While R. Landau tries to differentiate between the status of a properly slaughtered cow’s stomach (permitted on its own and only prohibited when mixed with milk) and an intrinsically prohibited stomach, R. Ovadiah Yosef explains that the Shibbolei ha-Leket explicitly rejects such a distinction and that perhaps R. Landau did not have access to an actual copy of the Shibbolei ha-Leket.
R. Ovadiah Yosef points out that the Mechaber (YD 99:1) does not distinguish between different types of bones, and therefore we are to assume that all are permitted regardless of their rigidity. R. Aharon Kotler however, contends that the Mechaber concludes as the Rambam, that the bones are rabbinically prohibited. The Mechaber seems to categorically permit all bones since he is only referring to cases of bones in mixtures (where the bones of an issur are added to the volume of permitted substances to calculate the total quantity of heter). R. Kotler claims that even the Mechaber admits that regarding eating non-kosher bones by themselves or when added deliberately to a kosher mixture to derive benefit from them, are rabbinically forbidden. R. Eli’ezer Yehudah Waldenberg agrees with R. Ovadiah Yosef’s analysis (in rejecting a similar prohibitive argument by R. Yehezkel Abramsky) to permit these bones.
IV. Do the copepods form a mixture with the water (ta’arovet)? If so, what is its status?
a. Hilkhot Ta’arovet:
Halacha postulates the concept that one object can become nullified, batel in a larger quantity of another. Therefore, if a spoonful of milk fell into a pot of meatballs cooking on the fire, it would normally create a prohibition of basar be-chalav; if there were 60 times more meat than milk (by volume) in the pot, the mixture is permitted. There are different sets of halachic rules governing different types of mixtures. Our present discussion will deal primarily with cases of liquids mixing with liquids, lach be-lach and solid objects mixing with liquids, yavesh be-lach, which in cases of mixtures of two distinct types, min be-she-eino minoh require 60 times more of the permitted item to permit the mixture. In most of the discussed cases, the halacha describes situations in which the issur item is entirely lost within the permitted substance and therefore, for one reason or another, the entire mixture is permitted. But what is the status of a ta’arovet in which the issur is still identifiable, nikkar ha-issur?
b. Nikkar ha-Issur:
Normally, the standard assumption is that when the issur is identifiable, there is no ta’arovet proper, since the substances are not really mixed. Many poskim claim that when an issur is nikkar in a ta’arovet, it is never batel even on a Torah level, presumably since it is not considered a ta’arovet. This is the approach of the Taz (104:1) as explained by Minchat Kohen (Sefer ha-Ta’arovet 2:3) and adopted by Pri Chadash (104:3) and Minchat Ya’akov (22:23, 85:57). The Minchat Kohen provides an alternate reading of the Taz that would hold that even if the issur is not nikkar at all, but can nonetheless be removed it is not batel even on a Torah level. This opinion is endorsed by Shulchan Aruch ha-Rav (ibid.). Nonetheless, other poskim address this question differently. The Ramo (YD 98:4) says that if forbidden fat fell into a large quantity of food (where there was 60 times as much food as fat), one must first add water to the mixture so that the fat will rise to the top and be removed. Only after doing so is the flavor of the fat batel in the rest of the mixture. Pri Megadim (YD Mishbetzot Zahav 98:7) explains that the fat is not batel because it is considered to be identifiable and therefore, the prerequisite for bitul, namely the creation of a mixture, ta’arovet, has not been satisfied (even) on a Torah level. The Kreiti u-Feleiti (ad loc.) ‘argues’ and explains that the fat is not batel because the mixture has a method of becoming permitted, a davar she-yesh lo matirim. Since if a person would simply remove the fat the mixture would be permitted anyway, the halacha does not allow bitul to occur in such cases. The concept of davar she-yesh lo matirim is of rabbinic origin, implying that on a Torah level, even if the issur is still visible within the ta’arovet, it is nonetheless batel.
c. Sha’arei Yosher’s approach:
The Sha’arei Yosher () explains that this fundamental disagreement regarding the status of a ta’arovet where the issur is visible is prevalent in other contexts. The Rashba (Torat ha-Bayit ha-Katzar 4:4 [38a in the Warsaw edition]) discusses a case in which a pot in which something non-kosher was cooked, forms a ta’arovet with other kosher pots (the person does not know which pot is forbidden, but is certain that there is one such pot). Each pot is nikkar on its own and instead of permitting the entire stock, the person can merely ‘kasher’ all of them. R. Shkop argues that the Rashba presumes that a ta’arovet where the issur is nikkar is only prohibited qua davar she-yesh lo matirim. Therefore, since there is much toil and expended effort required to ‘kasher’ the entire supply of cookware, the halacha renders the entire ta’arovet permitted. The Ra’ah however (Bedek ha-Bayit, ibid) argues that an issur that can be removed is considered nikkar and does not form part of a ta’arovet (but rather stands on its own) and therefore the entire ta’arovet is forbidden until every pot is ‘kashered.’ R. Shkop explains that the Ra’ah believes that a ta’arovet in which the issur is nikkar, can never become batel even on a Torah level. Therefore, he is unconcerned with the amount of effort required to bring about a permissive situation. While this case is somewhat different than the status of copepods in the water (the pots are yavesh be-yavesh, min be-minoh while the copepods in the water are yavesh be-lach, min be-she-eino minoh), it seems that R. Shkop assumes that these two approaches are valid in all realms of bitul be-ta’arovet. R. Hayim Oberlander (ibid, p. 152) argues that since the Shulchan Aruch (YD 102:4) follows the opinion of the Rashba, it must be the halachic conclusion that a ta’arovet in which the issur is nikkar, is batel at least on a Torah level. This would mean that the copepods are considered batel in the water as far as the Torah is concerned and we are left with the rabbinic strictures of davar she-yesh lo matirim and possibly of biryot (to be discussed later), both inhibiting bitul on a rabbinic level.,
d. Divrei Hayim’s approach:
When asked about the permissibility of a certain bug infested water source, Shu”t Divrei Chayim (YD 54) cited an alternate paradigmatic case to prove that whenever the issur is nikkar, it is never batel. The Rambam (ibid 3:15) and Rashba (Torat ha-Bayit ha-Aroch 3:6 [90b in Warsaw edition]) disagree regarding the permissibility of semi-solid butter obtained from a non-Jew, since the Gemara postulates that milk from non-kosher sources cannot form butter (the concern is that the the kum she-ba-chem’ah (semi liquid accompaniment) contains both kosher and non-kosher milk). The Rambam is strict despite this limitation, because the kum she-ba-chem’ah is nikkar on its own and therefore cannot form a functional ta’arovet. The Rashba is lenient as he claims that even solid objects that are individually identifiable can become batel amongst other solids in an appropriate volume. The Beit Yosef (YD 116) reads these two opinions as claiming that since nothing can be positively identified as assur – the issur is batel nonetheless. The Divrei Chayim posits that the disagreement between the Rambam and Rashba involves cases where the issur is nikkar but cannot be identified and removed (such as creatures that flowed through ‘contemporary’ filters) and even in such cases the Rambam is stringent. The Divrei Chayim proceeds to prohibit the water he was questioned about and goes so far as to say that if a person could move to a location that is free from these troubles and does not do so, he is considered to be intentionally violating the prohibition, meizid, and prohibited from drinking the water even for pikuach nefesh!
e. Torach Gadol:
The question according to R. Shkop’s approach then turns to how to define torach gadol. Based on Chazon Ish (YD 14:6), R. Vaye points out that the term torach is defined as difficulty in actually identifying the issur, as opposed to difficulty in merely finding it – as is the case by the copepods. He concludes that (aside from the question of biryah) such creatures should be batel. Furthermore, it seems logical to assume that whether or not one object can become batel in another is independent of advances in modern technology. The impression given by the halachot of Issur ve-Heter is that bitul is not a scientific phenomenon, but rather one mandated by the Torah. As such, it seems reasonable to assume that if in the past an object could not be removed and was deemed batel, the same criteria should apply today. R. Vaye seems to be pointing out that torach fits into this very scheme – it is the ability to identify the issur that is determining, not the technical ability to remove it. This also seems to be the thrust of the Tzemach Tzedek’s argument (ibid.) as well.
R. Bistritsky takes the opposite approach and argues that torach is defined as the amount of physical effort needed to remove an object from a ta’arovet. There is no more effort required to turn on a faucet running through a filter than to turn on an unfiltered faucet. As such, even according to the poskim cited above, this is a case where there is no torach required at all and therefore the copepods are not batel.
V. Bitul of a Biryah:
The Gemara in Chullin 100a (as explained by Tosafot ibid. s.v. biryah) posits that an issur that is a complete creature, a biryah, cannot be batel in any mixture regardless of the quantity (codified in Shulchan Aruch YD 100:1). A priori, this hindrance to the normal rules of bitul exists because a biryah is considered an entity onto itself, an object whose identity cannot be negated amongst other items and hence never batel. Most poskim assume that this bitul prevention is of rabbinic origin but that the item could be considered batel on a Torah level. The Maharil however, attempts to prove that Tosafot may have assumed that a biryah is not even batel on a Torah level. The Pri Chadash (100:3) notes however, that this seems to contradict Tosafot’s position in many places in the Gemara. Moreover, the ‘proof’ from Tosafot is a rather forced interpretation of that text and in fact he notes that the general consensus is that Tosafot also held that the prevention of bitul by a biryah is of rabbinic origin.
The Yerushalmi Terumot (10:5) however, as understood by R. Shimshon of Shantz (ibid.) argues that a non-kosher fish can be batel in 960 kosher fish, despite its status as a biryah. This claim is in apparent contradiction to the Gemara (Bavli) in Chullin. The Ohr Zaru’a (4:264) cites an explanation by R. Nissim Gaon that reinterprets the Yerushalmi to refer to the exuding flavor, ta’am of the non-kosher fish. He claims that the non-kosher fish as a biryah is never batel (as per the Gemara Chullin), but its ta’am however can be batel, but only in 960. The Ohr Zaru’a himself however, disagrees with this claim and argues that even for the Bavli, while the fish itself is never batel, if it were removed, its ta’am would be batel in 60 like the ta’am of any other issur. This opinion is agreed to by Shulchan Aruch YD (100:2). The Ra’ah, cites the Ramban for a similar but more limited application, that although the ta’am of ‘regular’ issurim is batel in 60, certain sharp te’amim require a larger quantity. He argues that the Yerushalmi is referring not to the fish itself, but to the juicy substance of the fish, tzir dagim – a sharp ta’am that is not batel in 60. The Rashba agrees with R. Shimshon of Shantz and the Ohr Zaru’a and explains that since the halachot of biryah are only of rabbinic origin, he will not be stringent in an apparent disagreement between the Talmuds. While this opinion is not cited by the Shulchan Aruch, many poskim are willing to incorporate the Rashba’s opinion in forming decisions in association with other criteria as well (e.g. using this as a safek to form a sfek sfeika). There are poskim who are even willing to create sfek sfeikot even when both presumptions are against the normative position of the Shulchan Aruch. Moreover, the Ketav Sofer argues that when the biryah is pegumah me’atzmah, inherently foul, perhaps similar to the chlorinated copepods, even the Shulchan Aruch would agree that it can be batel in a mixture of one to 960.
c. Intact and identifiable creatures:
While the added chlorine manages to kill almost all copepods before they reach the faucet, it also helps keep them intact – making them classic examples of biryot. However, as mentioned earlier, some of what appear to be copepods are merely the exoskeletal remains and therefore are not entirely intact. The halachot of biryah only apply to entirely intact creatures (YD 100:1) and a ta’arovet reverts to the standard regulations of bitul when the creature is incomplete (YD 100:1), even if the missing component is not necessary to maintain life (“eiver she-ein ha-neshamah teluyah bah”). This detail is relevant in two respects. First, as previously noted, a small percentage of the white specs in the water are only the molten exoskeletons of copepods, since the viscera and muscles have disintegrated. These objects are not considered biryot and the regular rules of bitul be-ta’arovet should apply. Moreover, many of the actual copepods that make it to the faucet are not longer completely intact, missing antenna, legs or other appendages. Second, it relates to the status of cooked copepods. Very preliminary studies have shown that most of the copepods present in agitated (mixed or otherwise disturbed – the precise necessary amount has yet to be established), boiling water are no longer completely intact.
It is important to note that even regarding the intact copepods, Shu”t Mishkenot Ya’akov (YD 36) limits the halachot of biryah only to creatures that are recognizable as such, but are too difficult to find in their current mixtures (“omedet be’einah u-bifnei atzmah ve-nikkeret, rak she’eino yadu’a eizeh ha-asurah”) and when they can exist on their own outside the ta’arovet. Since the copepods are arguably recognizable only as specs and not as creatures, they should be exempt from hilchot biryah.
VI. Purposely nullifying an issur (bitul issur le-chatchilah):
The deliberate negation of an issur, bitul issur le-chatchilah in any manner, is prohibited. Regarding already created mixtures (when the issur was not deliberately placed in the ta’arovet) the Mechaber limits bitul issur le-chatchilah to Torah prohibitions while the Ramo assumes that the accepted practice is to include rabbinic prohibitions as well (YD 99:6). Therefore, if boiling water were to render copepods no longer completely intact, this practice would be permitted by the Mechaber and forbidden by Ramo. However, the boiling may also render the copepods no longer nikkar and therefore, the permissibility of this action for the Mechaber would depend on the aforementioned disagreement of whether nikkar ha-issur presents a Torah or rabbinic prohibition.
The Ran however, explains that the prohibition only applies to a person who intentionally negates an issur so that he may benefit from that issur, when he actively desires that the issur add some flavor or substance to this ta’arovet. If the presence of the issur adds nothing to the benefit derived, there is no prohibition of bitul issur le-chatchilah. The Mechaber (84:13) uses this logic to permit heating honey that has pieces of bees in it so that it may become less viscous and amenable to sifting and the Tzemach Tzedek (Lubavitch, 41) extends this to permit making liquor out of infested fruits for this very reason. According to the Tzemach Tzedek, drinking boiled copepod infested drinking water should also be permitted, if the boiling the water were to entirely eradicate any visual sign of copepod presence in the water (so there would be no question of nikkar ha-issur). Precise studies with adequate controls are necessary however, to determine precisely what temperature and how much agitation is necessary to render all the copepods no longer intact.
VII. Prevalent minorities (mi’ut ha-matzui):
a. Types of mixtures.
The halacha defines two types of mixtures, each with its own set of very intricate regulations by using two paradigmatic cases. Many poskim have discussed these issues at great length especially regarding the applicability and distinction between these cases. The following will merely be a simplistic outline of this intricate, complex issue. The first case is where a piece of meat is found on the street in a locale that has nine kosher butchers and one non-kosher butcher. Since the piece was not found inside any of the stores, we assume that it came from the majority of stores (holchin achar ha-rov) and hence kosher. However, if a person in the same locale bought a piece of meat but cannot remember from which store he bought it, we are stringent and prohibit the meat. Since the uncertainty relates to which store the person entered, which is permanent (the store cannot be found anywhere else), the halacha states that kol kavu’a ke-mechtzeh al mechtzeh dami, loosely translated as when we are dealing with permanent factors, we ignore the simple majority and assume that the chance of incidence is 50% (thereby prohibiting the meat).
b. Pirash min ha-rov:
R. Hershel Schachter argues that since only some glasses of water contain copepods, drawing water from the reservoir is parallel to finding a piece of meat outside of the stores, since in both cases there is a certain likelihood that the piece (water) in question is permitted. The question that must be addressed is the status of this cup of water that has been drawn (and hence removed) from the water distribution system. As such we should follow the majority principle and not categorically prohibit the water. Since there are no distinct entities in the reservoir system that are copepod-infested and others that are not, the principles of holchin achar ha-rov should apply.
From the Torah’s perspective, a person must only concern himself with the incidence of issur, when that frequency exceeds 51% and at that point we can say holchin achar ha-rov. If a certain fruit is bug infested most (more than half) of the time, then the Torah prohibits consuming that fruit if it is not first checked and determined to be bug-free. However, if the incidence of issur is less than 51% there is no checking requirement. However, by rabbinic decree, if the incidence of issur is less than half but more than a “prevalent minority” (mi’ut ha-matzui), one must check that produce before consumption. For example, although there are various pathologies that render an animal a tereifah, we do not check each slaughtered animal for all of these signs, since their frequency is less than the required threshold (less than a mi’ut ha-matzui). Pathologies of the lung however (sirchot ha-rei’ah), are determined to constitute a mi’ut ha-matzui and as such must be checked by rabbinic decree. The same regulations apply to checking produce (and water) for insect infestation.
c. Determining mi’ut ha-matzui:
The precise frequency that determines prevalence (metzi’ut) is a matter of dispute amongst the poskim. The Rivash (Shu”t Rivash 191) posits that the necessary frequency is close to one half (karov le-mechetzeh) as well as being a normal occurrence (ragil li-hiyot). This is only slightly less than the 51% frequency that the Torah requires for checking. The Mishkenot Ya’akov (YD 17) goes to great lengths to prove that mi’ut ha-matzui is defined as a 10% occurrence and R. Shlomo Zalman Auerbach is oft quoted as endorsing the Mishkenot Ya’akov’s opinion. R. Schachter frequently cites R. Yosef Dov Soloveitchik’s opinion that mi’ut ha-matzui should be approximately 14.5%. R. Shemuel Wozner adopts a more subjective approach. Rather than the halachic definition of mi’ut ha-matzui being dependent upon specific percentages, the halacha looks to whether the prevalence of the incidence of the mi’ut in question is ‘rather prevalent’ (matzui harbeh). He vaguely defines this requirement that if in a random sampling of mixtures, most mixtures will have the mi’ut accompany the rov, it is considered matzui. R. Yosef Shalom Elyashiv is also quoted as defining matzui as less than 10%.
The most important element of this equation is to determine the functional unit of these calculations; we must determine the sample size before calculating frequencies. R. Hershel Schachter has argued that the unit should be defined by the normal amount of water drank at a meal by a single person, assumed to be approximately 16 ounces. Therefore, according to the Mishkenot Ya’akov if copepods are found in one out of every 10 glasses of water (1 copepod in 160 ounces), checking is required before drinking. Other poskim have defined other units to be used for this purpose and the conclusions should be drawn appropriately.
conducted for the Orthodox Union as well as DEP testing in response to consumer
complaints revealed varying concentrations.
The DEP checked various complainants’ homes as well as various water
mains throughout the five boroughs of
As of now it seems that no
conclusion can be drawn about the absolute concentration of copepods at the
faucet. It is clear however, that
studies of copepod populations and their seasonal cycling in the reservoirs has
little to do with their presence in tap water.
First, the independent studies performed by and for the Orthodox Union
were scientifically imprecise, with no proper protocol for obtaining, analyzing
or quantifying the finds. Second, the
DEP analysis used 500uM mesh filters to obtain their samples; the human eye can
distinguish between objects much smaller than that and copepods smaller than
500 uM are also halachically meaningful.
Last, it must be understood that various communities will have various
degrees of infestation. Testing
conducted at several homes within one block of each other displayed highly
varied results. Even at faucets where
copepods were present at specific times, none could be found two months
later. Different water currents at
various points in the system, as well as having no dead ends between terminal
branches of the system, vary the flow of water throughout the
distribution. It is furthermore unclear
how the changing weather affects this distribution. One of the largest water holding tanks in the
world is Under Staten Island, greatly altering the distribution of copepods
within those waters. Pipes to different
parts of the
e. Possible halachic considerations:
It may be the case that the Rabbinic decree of requiring checking for an issur occurring at as small an incidence of mi’ut ha-matzui only applies to Torah prohibitions. By Torah prohibitions, even when there is less than a 50% frequency, there is still some uncertainty, safek de-oraita. The rule by sefeikot de-oraita is that we are stringent and therefore the Rabbis instituted checking for a mi’ut ha-matzui as well. However, since uncertainty in rabbinic prohibition, sfeika derabbanan is ruled leniently, when the issur in question is only rabbinic in nature, perhaps there is no requirement to check even for a mi’ut ha-matzui. All of the various proofs brought by all of the poskim (except for one) to prove the precise frequency of mi’ut ha-matzui all deal with Torah prohibitions. If we are to assume that the copepods only present a rabbinic prohibition, either because they are batel on a Torah level (because they are not identifiable) or for any of the aforementioned reasons, such as not being batel as a biryah, perhaps even if they constitute a mi’ut ha-matzui, there is nonetheless no reason to obligate checking.
VIII. Wrapped in a garment (karcho be-siv):
R. Shlomo Zalman Auerbach notes that when a person knows that the water may contain sheratzim, ingesting them cannot be considered mit’asek (to be discussed below). The Avnei Nezer however points out an interesting possibility for leniency. He notes that perhaps one could argue that the water surrounding the sheretz prevents the sheretz from actually coming in contact with the person’s throat (chotzetz). Although one food item cannot act as a chatzitzah for another food item, he suggests that perhaps a liquid in fact can act as such a chatzitzah (he claims to be unsure as to this last point and as such will not rely on it entirely). Since the probability of a sheretz actually coming in contact with the throat is rather remote, the water should be permissible.
IX. How to approach this problem?
several places, the Gemara exclaims that Hashem does not allow for the
righteous to inadvertently violate prohibitions (ein hakadosh baruch hu
meivi takalah al yadam). Rabbeinu
Tam explains that this unique providence specifically encompasses prohibitions
of forbidden food items since it is exceedingly disgraceful for a tzaddik
to consume prohibited materials. In other areas, righteous people may indeed
unknowingly sin, however, by ma’achalot assurot, forbidden foods, Hashem
provides them with unique protection. The DEP claims that while there is not
documented evidence of the zooplankton concentration in the past, it is an
absolute certainty that their appearance in our water is not a modern
phenomenon. There have been hundreds,
perhaps thousands of gedolim and admorim who have lived in or
There are several approaches to answer this question. It must be noted however, that this unique providence is not sufficient grounds to permit what seems at face value to be prohibited. The simplest answer is to claim that this unique providence is evident in the supernatural realm. Hashem goes out of his way, violating the natural law to ensure that tzaddikim do not consume issurim. This in fact might be the Ritva’s approach to the issue; he claims that this guarantee protects tzaddikim from violating any and all types of issurim, not merely ma’achalot assurot. He proceeds to explain that when Yehuda ben Tabai inadvertently killed an eid zomem, it must have been the case that this witness, eid was liable for the death penalty for some other reason. It is simply inconceivable to assume that such a tzaddik could violate any issur – and this is the thrust of the guarantee. This answer is simply the acknowledgement that “ha-nistarot la-Shem Elokeinu” – we are not privy to the methods with which Hashem runs our lives and that He goes out of His way to protect tzaddikim from even inadvertent violations.
A second approach may be to reinterpret some of the cases brought in the Gemara. In all of the instances where the Gemara seems to invoke this claim, the person in question is not entirely innocent. In Chullin 6a, the case revolves around forgetting to remove ma’aser from produce and in Gittin 7a, R. Chaninah ben Gamliel brought about great fear in his home almost causing his family to feed him a forbidden food (our of fear that they had nothing else). In these cases there was a potential for a takalah, since ‘negative,’ prohibition-inducing actions were present. However, when the tzaddik in question exhibited no questionable activity whatsoever, there is not even a potential for a takalah and as such, no need for Hashem to protect these tzaddikim in these instances. Two of the other texts (Chullin 5b, Yevamot 99b) refer to instances of shogeig, unintentional violation. The poskim agree that violation, even be-shogeig that does not entail punishment, nonetheless entails a ma’aseh aveirah, a prohibited action. There is therefore also potential for a takalah and therefore a requirement for divine providence. Rashi in a number of these Gemaras clearly states that the guarantee specifically refers to actions committed be-shogeig.
The questions of gedolim drinking the water in the past, however, are cases of mit’asek – a prohibited action committed in the midst of a permitted one with no intention of committing the a prohibited action. The difference is that a violation be-shogeig is an intentional performance of the prohibited act, only that the actor is under the mistaken assumption that the act is permissible. Mit’asek is when a person who had no intention of performing the forbidden act altogether, but rather intended to perform a separate act and performed the prohibited one by mistake. The gedolim of the past had no idea that there were [possibly] forbidden sheratzim in their water and intended only to drink the water, but they drank copepods as well – the classic case of mit’asek. There is a disagreement amongst the Rabbis whether or not a violation be-mit’asek entails a ma’aseh aveirah or not. R. Akiva Eiger claims that mit’asek includes a ma’aseh aveirah but the Torah nonetheless exempted the transgressor from punishment. R. Ya’akov of Lissa argues that mit’asek does not entail any ma’aseh aveirah and as such there is no punishment. Perhaps according to R. Ya’akov of Lissa, since there is no ma’aseh aveirah at all – there is no potential for takalah and hence no guarantee of unique providence in these matters. Furthermore, elsewhere he argues that violation of rabbinic decrees even be-shogeig (not mit’asek) entails no ma’aseh aveirah anyway! It is therefore conceivable that gedolim drank water that we now know may be prohibited since they could not have known about the prohibition and were only mit’asek.
A third approach depends on whether the [possible] issur of drinking the water is from the Torah or by rabbinic decree. R. Elchanan Wasserman argues that perhaps the unique providence applies only to Torah prohibitions; it is possible however, for tzaddikim to unintentionally violate rabbinic decrees. The averted takalot only revolve around intrinsically prohibited objects, issurei heftza but not generically prohibited actions, issurei gavra. There is a whole school of poskim who argue that all rabbinic decrees are definitionally only issurei gavra and hence this unique providence does not apply to transgressing these prohibitions.
All these rationales however, are highly speculative and this notion of unique providence (especially by ma’achalot assurot) seems like a serious consideration in determining the halachah (as Tosafot used it). R. Yosef Engel expands the term “tzaddik” in the above dictum to include actions performed by all of Kelal Yisrael, as Yesha’ayah (60: 21) states, “ve’amech kulam tzaddikim” – and your nation shall be entirely righteous. R. Engel notes that specifically in areas of ma’achalot assurot Hashem will not allow a takalah to befall all of Kelal Yisrael. This clearly only strengthens the above questions. While it may in fact be insufficient grounds in itself to provide for leniency, it may allow poskim to rely on possibly lenient opinions when they do justifiably arise. Even if it cannot go that far, it does and must provide a proper motivation and frame of mind when arriving at final conclusions.
Should the poskim conclude that drinking copepod-infest water is indeed forbidden, filtering the water is a rather straightforward method of avoiding this problem. There are various models and varieties that can remove various substances from the water. The simplest type, a particle filter is sufficient to alleviate the copepod concern, while other filtering elements such as activated carbon are added for aesthetic reasons. Some filter all water entering the home, some under the sink and some on the faucet. Care must be taken when choosing a specific model in that not all models can filter hot water. The most important criteria of filters for these purposes is the pore size of the filter itself, measured in microns (uM). While many filters advertise a specific pore size, closer examination reveals that this is more often than not a claim of nominal pore size, not absolute pore size. This means that a 50uM filter will catch most, but not all 50uM objects. However, as object size increases, so does the filtration rate of these units. Since the average person cannot distinguish objects smaller than 50uM, a filter with such a pore size should suffice, as the vast majority of the copepods found at the tap are adults of much larger dimensions.
The permissibility of filtration on Shabbat is very complex, as it relates to the prohibitions of borer and meraked. The complexity stems from the question of removing an item from a mixture, where the lack of removal renders the whole mixture prohibited. This question is beyond the scope of this paper, but a Rabbi should be consulted by people who install filtration systems on their water supply.
The issue of copepods is an issue that touches the very practical core of many people’s lives and is of tremendous importance. Water is a basic necessity and must be respected as such. This is not only a question about single faucets, but also how people will relate to neighbors and friends who do not filter their water. It will reflect kashrut policies in restaurants as well as food production factories. It will also have a heavy impact during the hot summers, especially on the very young and the very old whose hydration needs increase dramatically with the outside temperature. It will also impact on hospitals and old age homes, where patients and residents may not have as much say in the food they eat. This is one of the more profound and influential piskei halacha of our time. Hopefully this article has served as a background to understanding some of these complex ideas.
 1000 uM = 1 mM; 1000 mM = 1 m = 100 cm; 2.54 cm = 1 inch.
 See “Why
 Makkot 16b.
 At a distance of about a meter, a person can see objects larger than 100uM, slightly smaller than half the size of a period at the end of a sentence in a newspaper (see www.madsci.org/posts/archives/feb2000/951008843.Gb.r.html.).
 Many poskim have already discussed this issue at length – all agreeing that microscopic creatures are not within the realm of halachic prohibitions. See Binat Adam (38:8 ff 34), Arukh ha-Shulhan (84:36), Shu”t Tuv Ta’am va-Daat (, 3:1:160), Iggerot Moshe (YD 2:146), Yehaveh Da’at () and the sources cited therein.
 In reality, only a tiny percentage of copepods make the journey from reservoir to faucet while avoiding their demise.
 Shu”t Shevet ha-Levi 7 (YD 122).
 It is not perfectly clear that R. Wozner would rule similarly in our case. At the very end of the responsum he explains that even the movement of the creatures in question could not be seen without visual aids. Copepod motion in the reservoirs is easily viewed by the unaided human eye and therefore it is not entirely clear what R. Wozner would rule concerning copepods.
 Cited in Shemirat Shabbat ke-Hilkhetah (chapter 3, note 105). A parallel idea is recorded by R. Hershel Shachter in the name of R. Kalman Epstein who cites it from R. Yisrael Gustman zt”l who quoted it in the name of R. Hayyim Ozer Grodzinsky zt”l.
 R. Schachter penned two separate responses to this issue, in the first lenient and in the latter strict. The second responsum can be read in translation in Kashrus Magazine 25:1 (2004), 199.
 Chazon Ish YD (5:3), EH (27:3).
 Shemirat Shabbat ke-Hilchetah, ibid.
 Some point out that this may not be the only way to read the Shemirat Shabbat ke-Hilkhetah. They note that R. Neuwirth never actually states that R. Shlomo Zalman reversed his opinion but only that after some time he had heard that the Chazon Ish was stringent.
 The pesak
was published in Yated Ne’eman, on
 It is possible to argue that R. Ovadiah Yosef may indeed agree with R. Wozner and R. Auerbach's initial assumption. In Shu”t Yabi’a Omer YD (), he addresses the question as to whether one may enter a restroom while carrying certain Israeli currency that depicted parts of Sefer Yesha’aya (from the Dead Sea Scrolls). While it was clear that that there was some text of Sefer Yesha’aya on the currency, its content could not be deciphered without visual magnification. He simply argues that all sub visual phenomena are beyond the pale of normative halacha. By not distinguishing between microscopic entities and those that are visible to the unaided eye but unidentifiable as such, he thereby implicitly rejects the Chazon Ish’s approach. It is not clear however, that a parallel can be drawn between that case and ours. First, one can argue that the status of letters is determined by what can be seen by the average reader – representing criteria independent of other areas of halacha. While R. Ovadiah Yosef does not mention such an argument it is unclear what he would claim about the copepods. Second and more importantly, R. Yosef may concede that Rashi’s definition of a sheretz (and the logical derivative of that definition as explained by the Ben Avraham to be explained) is primary in this discussion and outweigh any other considerations, and thus prohibiting the copepods.
 Eruvin 28a, s.v. zir’ah. The halacha does use the term sheretz to refer to larger creatures as well, such as the shemonah sheratzim (Shabbat 107a). It appears that Rashi is simply referring to the smaller types and not making linguistic generalizations.
 Cited by Darchei Teshuvah (84:45).
 There may be a parallel structure by the prohibition of eating freshly hatched chicks before they ‘open their eyes’ as a derivative of the prohibition of sheretz ha-of (Beitzah 6b). However, once they mature somewhat and ‘open their eyes’ they are permitted via shehitah. In both cases, a certain life cycle event can affect in change in prohibited and permitted statuses.
 His second responsum on the issue. Apparantly R. Schachter assumed that the criteria of the Ben Avraham outweigh the apparent conclusion based on the Chazon Ish’s interpretation of halachic development, especially in light of the fact that the Chazon Ish himself was stringent in this regard.
 Sha’ashu’ei Oraita 3 (2004), 152.
 Ohr Yisrael 36 (2004), 203 – 204.
 There are several other proofs that have been argued regarding this matter but seem inconclusive. For example, R. Hayim Oberlander (Ohr Yisrael,177) claims that while the Gemara (Shabbat 107b) states that lice are spontaneously generated, the amora’im were well aware of the existence of lice eggs. He claims that while these eggs were indeed visible, they could not be identified as eggs and therefore lice were considered to be the product of spontaneous generation and not sexual reproduction. He claims that a similar logic should apply to the copepods (since they cannot be identified as creatures, they should be ignored despite their visibility). However, it could easily be argued that Hazal simply assumed that the eggs were also spontaneously generated as were the lice that arose from within them, making this source somewhat irrelevant.
 As an important corollary, one should note that many of the poskim addressing the problems of ‘un-filterable’ water sheratzim counsel their questioners to first boil the water then filter it again. For some reason they assumed that dead sheratzim are more easily caught by the filter. Some suggest that it might be because they assumed that the live sheratzim crawled through the very fine pores of their filters and when dead this would not happen. This seems highly speculative since the major force pushing the sheratzim through the filters is the falling water. Assuming that they were only filtering a jug or a cup at a time, the filtration itself should only take a few seconds. As such, even if the sheratzim could migrate to more porous areas of the filter (or even spread apart the fine fibers of the filters to create larger pores) their movement would have to be very fast (especially considering their minute size). Secondly, the locomotion of zooplankton on dry surfaces is highly questionable. Moreover, the sheretz would have to travel horizontally through an intense vertical gravitational force of falling water, making this movement rather difficult. Perhaps one could suggest that boiling the water killed off all the creatures and they still made it through the filters. However, since they were immobile they were not identifiable as creatures but merely as specks of dust. Since they could not identify any issur, they permitted the water.
 The plain meaning of the Gemara seems to refer to spontaneously generated creatures. It is important to note however, that the Gemara never actually makes this claim outright. The Rambam (Ma’achalot Assurot ) however, uses the verb “created.” The Mechaber refrains from this language and says gedeilim – the place where the creatures germinate or grow. It is somewhat beyond the scope of this paper to discuss the halachic view of spontaneous generation and will be discussed only briefly later on regarding the position of the Chazon Ish.
 The disagreement stems from a question of kelalei ha-pesak, of deriving principles from the Gemara. Cf. Maggid Mishnah (ibid.) and Taz (84:1) who use different approaches to this matter to explain Rambam’s position.
 Cf. Shu”t Yechaveh Da’at () in the footnote as well as Shu”t Yabi’a Omer HM (6:2) for an extensive analysis of the application of this rule in several areas of halacha.
Edward B. Reed (communication to R. Lach cited as an appendix to his
report). Dr. Reed has taught courses
dealing with and conducted research on copepods for nearly fifteen years at
 Chazon Ish, Hilchot Tola’im 14(1):10.
 Several answers have been suggested for this question. Many poskim believe that since halacha is unconcerned with subvisual phenomena, if the newborn sheretz is so small that it cannot be seen, the adult has the status of germinating from nothing (visual = halachic). Others claim that perhaps at another historical period there were spontaneously generating creatures that fell under these categories.
 R. Feinstein’s ruling as noted previously. Shu”t Chatam Sofer (EH ) claims that a body of water that has only an outflow is still considered to be as yamim u-nehalim despite the incomplete parallel to actual rivers.
 If we do not accept this proposition then there is no such real ma’ayan in the world today since all springs ultimately derive their water from rainfall. While Darkhei Teshuvah YD (201:215) cites many authorities that argue on the conclusion arrived at by the Mishkenot Ya’akov in his particular case, they all agree to this premise at least on some level.
 Shu”t Meishiv Davar 41.
 Shu”t Tzemah Tzedek YD 176.
 Also see Ramban to Devarim (8:5) where he explicitly defines ma’ayanot.
 There is some contribution by direct rainfall into the reservoir itself, but it pales in significance to the contribution from the rivers flowing into it.
 Some have cited Shu”t Meishiv Davar () in opposition to this proposition. He states the halacha that if the sheratzim (in the river in question) derived from snow or cisterns they are permitted even when they enter the river. If he meant that the water in question originally derived from rainwater – then he has effectively included every single body of water on earth and eliminated the halachot of ma’ayanot and of forbidden sheratzim. As such, it seems more likely that he simply referred to snow that melted directly into the water without first travelling underground and in effect did not add anything new with this line.
 For a comprehensive treatment of this topic see Sefer Tahorat Mayim by R. Nissan Telushkin, pp. 7 – 9.
 Kuntres, pp. 20 – 22. He actually makes several other points as well regarding this matter, based on the mistaken notion that the reservoirs derive entirely from rainfall. As discussed earlier, each reservoir has rivers that lead into it and as such these arguments will not be analyzed.
 Quoted by the Rambam in Rotzeach u-Shemirat Nefesh and Shulchan Aruch Choshen Mishpat 427:9.
 It is important to note that the Issur ve-Heter (41:7) cites the Rambam differently as referring to bereikhot, enclosed bodies of rainwater and not neharot. As mentioned above, the creatures residing in the former are permitted and therefore at night there is only a problem of danger and not prohibition. This variant text does not appear in any modern edition of the Rambam nor is it cited as an alternate version in the Shabtai Frankel edition.
 Bava Metzia 116a. Both Rambam (Malveh ve-Loveh 3:1) and Mechaber (HM 97:14) rule like R. Yehudah who denies this rationalization process. Shu”t Chatam Sofer (YD 254) however, is willing to use such rationales to establish a stringency.
 Sefer va-Yikra Yehoshu’a, YD hilchot tola’im 2.
 While he concludes that it is nonetheless appropriate to act stringently, it seems that it is out of concern that the sheratzim actually originate in the ma’ayan waters.
 Sha’ashu’ei Oraita, 155 – 156. He notes that there are many gates that control the outflow of water from this reservoir with each independently controlled. There are therefore no gates that are open continuously for longer than a specific given period.
ha-Bayit ha-Katzar (3:1) [67b in the
 Beit Yosef YD (84) s.v. katav ha-Rambam, also see Taz (84:5) and Shach (84:4, 10).
 Shu”t Shevet ha-Levi YD (7:123:4).
 R. Wozner posits that since the prohibition is question is from the Torah we should adopt the Issur ve-Heter's stringent position. He points out however that the Pri Megadim (Mishbetzot Zahav YD 84:5) attempts to prove that the Issur ve-Heter really has a similar logic as the Taz and is not quite as extreme as the Pri To’ar attempted to show. Therefore, ideally we should follow the Pri To’ar’s approach but he is readily willing to be more lenient in certain situations.
 Ibid, p. 178.
 For these purposes it must be noted that ‘migration’ is used to mean any movement of sheratzim from their natural habitat, be it by voluntary motion or water currents.
 The Maggid Mishnah (ad loc) explains that they disagree about the text of the Gemara in question, where the Gemara seems to conclude that we should act strictly. The Rambam read “pirshah meitah,” meaning that the sheretz ‘migrated’ post mortem, while the Rosh read “pirsha u-meitah,” it ‘migrated’ and upon impact it died.
 For a thorough and rather extensive treatment of this issue see Yalkut Yosef 9, pp. 5 – 44, and the opinion of R. Ben Zion Abba Sha’ul quoted therein.
 Although the Ramo does not comment on this point in the Shulchan Aruch, the Shach does quote the Ramo’s opinion in Torat Hatat (46:5, 47:2) as concluding like the Rosh.
 While R. Oberlander does not cite a source for the Pri Megadim, it seems to be YD Siftei Da’at (84:12, 24, 45). It seems somewhat unclear however, whether the Pri Megadim is endorsing the Minhat Ya’akov’s opinion, or simply mentioning his approach and explaining how it applies to various issues.
 The status of a sheretz that exits one kli to enter another is permitted (as per Shach YD 84:4). Therefore, there are no problems with the water exiting the faucet and entering any other vessel.
 Hasagot, no. 5.
 This argument raises other interesting derivative issues. For example if a reservoir is indeed considered a kli, a niddah may not become tehorah after immersing in it (after counting her seven clean days). Water in a kli is discounted from counting as a mikvah and according to R. Raitport the reservoirs are disqualified.
 Tzelach, Chullin 89b, s.v. sham ve-noheig (first entry). Also see Shu”t ha-Bah 137.
 Shu”t Ahi’ezer 3:33.
 Shu”t Yabi’a Omer YD ().
 As per
the Rashba’s opinion in Torat ha-Bayit ha-Arokh (4:1) [109a in the
 Shu”t Mishnat Rabbi Aharon, YD (also 16:9).
 See Shu”t Tzitz Eli’ezer 4 where R. Abramsky’s position is recorded along with R. Waldenberg’s disputing comments.
 Pri Chadash (99:6), but see Kaf ha-Chayyim (168:46, 486:1).
 Shulchan Aruch, YD (92:2).
 Shulchan Aruch, YD (98:1).
 R. Belsky (Sha’ashu’ei Oraita, 153) argues that the Ramo’s position is entirely irrelevant to the question of copepods since the Ramo refers to a case where the forbidden fat is certainly in the ta’arovet. The certainty that the issur is present results in certain consequent stringencies. As noted earlier, since the copepods are only questionably in each glass of water, the Ramo’s conclusion is irrelevant to our discussion.
 The Gemara Chullin 97b (recorded Shulchan Aruch YD 98:4) explains that since we cannot ascertain how much flavor is given off by any item, we always assume that the maximum possible exuded flavor equals the volume of the item in question.
 This logic follows the reading of Rashi in Beitzah 3b, s.v. she-yesh. The Ran in Nedarim 52a, s.v. ve-kashya however, provides an alternate and fascinating approach to the concept of davar she-yesh lo matirin and expounds on the greater question of how bitul works in general. The difference between these two approaches has several ramifications for various cases, but is not relevant to our discussion.
 The major difference between these opinions is whether or not the issur would be batel if the addition of water would ruin the taste of the food. For the Pri Megadim, one is required to add water to the mixture to remove the fact even if it will ruing the taste of the food, since as long as the issur is visible, the Torah does not consider this to be a ta’arovet. R. Eyebeshutz however, argues and claims that since davar she-yesh lo matirim is only of rabbinic origin, the Rabbis did not prohibit ta’aruvot where the method of employing the matir in question would ruin the food item. He therefore claims that in such cases, the mixture is permitted even without removing the fat.
 In the published version of this article, I indicated that the issur is nikkar because each individual pot is recognizable on its own. R. Baruch Simon pointed out that this is indeed incorrect and the Ra’ah’s reasoning has been corrected in this version. His reasoning however, does not influence the rest of the discussion.
 The Shulchan Aruch however, may not be quite that unambiguous. The Mechaber says that although normally a davar she-yesh lo matirim prevents bitul (albeit on a Rabbinic level), when application of the matir requires a tirha yeteirah (extra expended effort), the Rabbis suspended their decree and allowed bitul to proceed as it would have normally. This does not outwardly contradict the opinion of the Ra’ah since he will claim that the Mechaber’s argument is correct, albeit limited to cases where the issur is not nikkar. Since the Mechaber did not outwardly contend that the issur was indeed nikkar in this case, it seems difficult to conclude what his position is on this matter.
 The Sha’arei Yosher also brings proofs from a certain halacha relating to a ta’arovet of permissible and forbidden sechach, in which the Mechaber also seems to adopt the lenient position. However, the rest of the piece is Sha’arei Yosher is devoted to explaining why the case of sechach may not be paradigmatic for the rest of halacha. It seems difficult to conclude from these cases that the Mechaber actually held this lenient position.
 He cites a Shu”t ha-Rashba (84 [unclear which responsum he refers to]) who says that regarding a chatichah ha-re’uyah le-hitkabed bah, one must search for the chatichah and remove it in order to permit the ta’arovet. The Divrei Chayim explains the disagreement between the Rambam and Rashba in this way so as to insure no inconsistencies between the Rashba in this responsum and his opinion in Torat ha-Bayit.
 There are two points however, that require clarification before applying the Divrei Hayim’s approach to the copepod question. The Rambam does not unequivocally adopt the position attributed to him; he cites some of the Geonim (miktzat Ge’onim) who were stringent and some who were lenient, although the Divrei Hayim assumes that Rambam adopts the former position. In the next halacha, the Rambam claims (yir’eh li) that if all the milk were boiled off then the butter would be permitted – indicating that he follows the stringent opinion. Since the Rambam does not explicitly make this claim, it is quite possible that he is saying that even for those who are stringent, boiling off the excess milk should alleviate the problem without offering his own opinion on the matter. A rabbinic decree (gezeirah) is enacted to protect people from a possible violation of Torah law. Perhaps the disagreement amongst the Geonim revolves around the disagreement between the Rambam and the Rashba. Those who favor the Rashba’s opinion (an issur that is nikkar is batel on a Torah level) will not enact a gezeirah to ‘protect’ violation of another rabbinic prohibition. Uncharacteristically, the Mechaber (Shulchan Aruch YD 115:3) is similarly ambiguous. He states that one should not protest against the lenient practice in this matter; however, if the majority of the community acts stringently, then one should not deviate from the common practice. The normative decision does not seem to be in accordance with the stringent opinion but rather dependent on local custom. Moreover, the Tzemach Tzedek (Lubavitch) (Shu”t Tzmach Tzedek YD 70, arguing on his grandfather in Shulchan Aruch ha-Rav (466:9)) argues that the Rambam’s opinion is an extreme stringency (chumra gedolah) and is not necessarily halachically mandated.
Second, the proof from the Shu”t ha-Rashba does not definitively apply to the copepods. By a chatikhah ha-re’uyah le-hitkabed bah, the issur is identifiable as such – you can look at the piece in question and state that this piece is pork. As mentioned previously, the copepods are not [easily] identifiable as such. Often a microscope is needed to positively distinguish a copepod from a speck of dust and is definitely required to specifically distinguish full copepods from their exoskeletal remnants. R. Moshe Vaye (Bedikat ha-Mazon ka-Halacha, chapter 7 footnote 1) cites both R. Shlomo Zalman Auerbach and R. Yosef Shalom Elyashiv as positing that something that is not a biryah and cannot be positively identified without much toil (torach gadol) is batel in a ta’arovet. While the intact copepods do present a problem of a biryah (to be discussed) that would only prevent bitul on a rabbinic level, having already become batel on a Torah level. Moreover, a careful reading of the Tzemach Tzedek (ibid) reveals that he indeed agreed to this proposition as well. The question he dealt with concerned fragments of creatures that could not be filtered. After rejecting the Rambam’s opinion as unnecessarily stringent, he claims that these creatures should be batel because they are not recognizable as biryot. He could have, but does not say, that they are batel because they are not biryot, but rather because they are not recognizable as biryot. This also seems to be the position of Iggerot Moshe YD (4:2).
 Bedikat ha-Mazon ka-Halachah, ibid.
 Ohr Yisrael, ibid. p 212.
 The Avnei Nezer (YD 81) offers an additional interesting point of leniency. When a person knows that water may contain sheratzim, drinking that water and ingesting those sheratzim is not categorically considered to be mit’asek (a prohibited action committed in the midst of a permitted one with no intention of committing the a prohibited action), but rather willful violation (discussed by R. Shlomo Zalman Auerbach in Shu”t Minchat Shlomo 2:61:1). The Avnei Nezer however notes that perhaps one could argue that the water surrounding the sheretz prevents the sheretz from actually coming in contact with the person’s throat (chotzetz). Although one food item cannot act as a chatzitzah for another food item, he suggests that perhaps a liquid in fact can act as such a chatzitzah (he claims to be unsure as to this last point and as such will not rely on it entirely). Since the probability of a sheretz actually coming in contact with the throat is rather remote, the water should be permissible. He claims that even if one were to ingest a sheretz in this matter (that it would touch the throat), since it is only a remote possibility that it will do so (not a pesik reishei), it is considered as an unintended action (davar she-eino mitkaven).
 An alternate, subtler approach is to argue that a biryah cannot even form a ta’arovet with other substances. Since its identity is always retained, the mixture of the biryah with other substances is not defined as a mixture but as two unmixed separate objects.
 Cf. Rambam ibid. (16:6).
 Shu”t Maharil (76), based on Tosafot, Bava Metzi’a 6b, s.v. kafatz.
 The Shu”t ha-Rashba (1:271) already notes that he does not understand the requirement of specifically 960. While it mathematically comes out to be 16 * 60 (60 being the ‘magic’ number in Hilkhot ta’arovet), this function does not seem to have any other correlation in halacha.
 Bedek ha-Bayit, Bayit 4, Sha’ar 1 (14a), s.v. ‘od.
 Torat ha-Bayit, ibid. and Shu”t ha-Rashba ibid..
 Cf. Machazik Berachah (52:5), Shu”t Mishnat Rabbi Eliezer YD (2:1) and sources cited in Shu”t Yechaveh Da’at 5:54.
 Another interesting ramification of adding the chlorine is rendering the copepods somewhat destroyed – nifsedu legamrei. The Shulchan Aruch (YD 84:17) states that a person may eat a ‘burned sheretz’ (saruf) for medicinal purposes since it is considered like dust. The Minchat Ya’akov (46:9) cites several poskim as permitting such a person to ‘burn’ a sheretz for this purpose and that even a healthy person may eat such a sheretz as long as he does not ‘burn’ it for this purpose (cited by Pri Megadim (MZ 84:23)). The Yad Avraham (YD 84) however, explains that a healthy person may not eat such a sheretz because the very act of specifically eating this sheretz shows that he does not consider it to be as dust but rather as something desirable (achsheveih). R. Raitport argues that the chlorination process is entirely parallel to the ‘burning’ discussed by the Mechaber (Kuntres, 33). There is clearly no problem of achsheveih here since nobody actually desires to eat the copepods and furthermore, R. Hayim Ozer Grodzinsky claims that achsheveih only applies when eating independent issurim, i.e. not as part of a ta’arovet (Shu”t Achi’ezer 3:33). While both burning and chlorination leave part of the sheretz intact (not just a pile of ash) it would seem that fire is more thoroughly destructive than chlorine; burning leaves the sheretz charred, while chlorination keeps most of their bodies intact. The poskim must determine whether the copepods are indeed considered sufficiently ‘burned’ and how that relates to the question of achsheveih (as well as possible ramifications for questions of tum’ah).
 Shach YD (100:6).
 He proves this from Beitzah 3b where the Gemara differentiates between when a person crushed a forbidden fig onto the top of a barrel and that barrel subsequently was mixed up with others and a case where a person crushed a forbidden fig into a barrel and he is unsure where in the barrel the fig ended up. The former case is not batel because the barrel is a davar she-be-minyan while in the latter case the forbidden fig is batel. Rashi (ibid. 4b, s.v. hakhi) explains that since the figs stick together and the forbidden is not independently recognizable it is batel. He sees no reason to differentiate between Hilkhot davar she-be-minyan and Hilkhot biryah.
 There are several other criteria that are required for an issur to count as a biryah. One is that it must be assur mi-techilat beriyato, forbidden from the time of its creations (unlike neveilah for example where the issur only arises after death) (Shulchan Aruch YD (100:1). R. Yonatan Eyebeshutz (Kereit u-Feleiti YD (100:4)) argues that creatures that grow from (in) fruits no longer connected to trees should not count as biryot, since the creatures only become assur when they exit the fruit and as such are not assur mi-techilat beriyatan (see R. Shlomo Kluger (Shu”t Tuv Ta’am va-Da’at (3:1:160) and ibid (2:162)). This position is also suggested by Yeshu’ot Ya’akov (YD 84:1) and accepted by R. Betzalel ha-Kohen of Vilna, cited by Mateh Yehonatan YD 100) extends this position to apply to creatures that grow from (in) water since they too only become forbidden once they leave their original water source. Many poskim however reject this approach. The Tur ha-Even (26) argues that assur mi-techilat beriyato means to say that nothing physical must take place to make this issur into a biryah. Since these water creatures are unaffected by their journey into different waters and are then considered to be forbidden they are within the realm of assurim mi-tehilat beriyatan. A similar stringent approach is offered by the Chavot Da’at (100:5) as well as Chida (Mahazik Berakhah 84:10). Both the Pri Megadim (Siftei Da’at 84:31) and R. Ovadiah Yosef (Shu”t Yechaveh Da’at () in the footnote; R. Yosef has a lengthy discussion there about this issue and cites numerous positions on this issue) claim however that none of the poskim seriously entertain R. Eyebeshutz’s approach and it is ultimately rejected in halachic decision-making.
A second criterion cited by many poskim that if an issur was created as part of a ta’arovet then it is more amenable to bitul. The Mechaber (OH 320:2) states that although juice that comes out of grapes on Shabbat is forbidden, nonetheless if the juice comes out directly into already prepared (from before Shabbat) juice, the mixture is permitted for use on Shabbat. The Magen Avraham (320:5) explains that although the issur (juice that came out on Shabbat) is a davar she-yesh lo matirin (it will be permitted after Shabbat anyway), since it was never nikkar on its own outside of the ta’arovet, it is batel. The Mordechai (Chullin 737) takes the diametrically opposed approach; bitul can only occur when the issur existed independently before becoming mixed in the ta’arovet (quoted in Shulchan Aruch, EH 169:40). R. Raitport (Kuntres, p. 23) explains that the Mordechai’s logic only applies in the very limited case of concomitant creation of both the issur and the heter. However, when the heter existed previously, and the issur was created into a ta’arovet with that heter, the Mordechai agrees that bitul is possible (see however, Shach YD (), Sha’ar ha-Melech, Hilchot Yom Tov (), Shu”t Avnei Nezer YD 81 and Shu”t Noda’ bi-Yehudah YD ( – 55)).
The Avnei Nezer (YD 79:1) explains that the usage of the leniency of noldu be-ta’arovet is limited however, to cases where the prohibition is one of davar she-yesh lo matirin. The applicability of these criteria would depend on the aforementioned disagreement between R. Eyebeshutz and the Pri Megadim as to the reason that an issur ha-nikkar is not batel. Even if we are to assume like R. Eyebeshutz that it is only because of davar she-yesh lo matirin, the poskim need to determine whether or not this leniency is valid since the copepods also present a problem of biryah. It is unclear whether or not noldu be-ta’arovet is sufficient grounds to remove only part of a potential issur – meaning that even if we alleviate the problem of davar she-yesh lo matirin, we are nonetheless still left with the question of biryah.
 Avodah Zarah, 12b (Hilchot ha-Rif) s.v iba’aya, also in Maharam of Ruttenburg (190) and Shu”t ha-Rashba (1:467).
 Cf. Shu”t Yabi’a Omer YD (1:6:5, 1:8). Also see Yalkut Yosef 9, p. 245 who notes that although the Kenesset ha-Gedolah argues that bitul issur le-chatchilah applies to objects that are certainly infested (as opposed to those only questionably so), his opinion is rejected by the later poskim.
 It is important to note that in the Mechaber’s case, the purpose of the boiling is to remove the bees entirely from the mixture; the only question is regarding the ta’am that the bees have exuded into the honey. The Tzemach Tzedek however goes farther and is even willing to permit the liquor, even though the insects have not been removed. The Tzemach Tzedek’s case is entirely parallel to our water even if the Mechaber’s might not be entirely so.
 Pesahim 9b, Ketubot 15a, Chullin 95a, Niddah 18a.
 It is beyond the scope of this paper to discuss whether this rov really ‘determines’ the status of the piece in question (birur) or is merely the way we must relate towards this questionable piece (hanhagah).
 Pri Megadim YD, Siftei Da’at (84:28).
ha-Bayit ha-Aroch (3:2) [33b in the
 Bedikat ha-Mazon ka-Halacha, p. 181. Also see Shu”t Beit Ephrayim YD 6 on the issue of a safek issur.
 Based on what he determined was the actual incidence of sirchot in cow lungs in his time.
 Shu”t Shevet ha-Levi YD (4:81).
 It seems that he is trying to say that in five groups of one hundred items each, each group has at least 10 instances of the mi’ut and not that four groups have 15 each and the fifth has none at all (even though in the larger picture the latter scenario has a higher percentage of issur in the entire sample).
 Bedikat ha-Mazon ka-Halacha, ibid.
 The one case that deals with a rabbinic prohibition is checking for chametz, bedikat chametz in Pesachim 4b. It is possible to argue that the case in question is for a Torah prohibition since it is regarding checking for chametz in a neighbor’s home (where there is no possibility for bittul chametz since the chametz belongs to somebody else). Alternatively, one can argue that bedikat chametz is a special Rabbinic enactment, as is evidenced by the rather specific regulations and not paradigmatic for these issues (see Maggid Mishnah, Hilchot Chametz u-Matzah ). The Gra (YD 1:4) however, uses this case in explaining others, seemingly suggesting that it is paradigmatic and not idiosyncratic. Further analysis is necessary to see whether or not this suggestion plays out in the poskim.
 Shu”t Minchat Shlomo 2:61:1.
 Shu”t Avnei Nezer, YD 81.
 The Avnei Nezer claims that even if one were to ingest a sheretz in this matter (that it would touch the throat), since it is only a remote possibility that it will do so (not a pesik reishei), it is considered as an unintended action (davar she-eino mitkaven).
 Chullin 5b s.v. tzaddikim, Shabbat 12b s.v. Rabbi Natan, Gittin 7a s.v. Hashta.
 Cf. Pesachim 106b, Shabbat ibid., Yevamot 99b, Chaggigah 16b where Yehudah ben Tabai inadvertently killed an eid zomem!
 Chullin 6b.
 The Chiddushei ha-Ran (Chullin 7b) states the exact opposite and claims that the divine guarantee only applies in cases where there was no peshia’ah whatsoever. This seems rather difficult to understand since the cases in the Gemara all do seem to be instances of peshia’ah and the Ran does not provide alternate readings of these Gemaras.
 In Yevamot, when the slave who mistakenly was thought to be a Kohen ate terumah, the action was only shogeig.
 Even if one were to argue that some of these cases are mit’asek and not shogeig, these are nonetheless cases of mit’asek ba-chalavim ve-arayot she-ken neheneh that are of a different variety than the standard mit’asek that will be discussed shortly.
 Shu”t Rabbi Akiva Eiger OH 8. He limits this definition to all areas of halachah excluding Hilchot Shabbat. The prohibitions of Shabbat require a higher threshold of ‘intent’ to engender liability.
 Mekor Chayim 431 (beginning of the chapter and also see the Kuntres Acharon op cit), cited by R. Akiva Eiger ibid. His stance is in fact more nuanced and he distinguishes between mit’asek that involve actions as opposed to those that are violated passively. In what may at first appear slightly counterintuitive, he argues that the first involve no ma’aseh aveirah while that latter in fact do. Drinking water clearly involves an action and therefore are of the former category that entail no ma’aseh aveirah.
 Netivot ha-Mishpat, Be’urim (234:3).
 Kovetz ‘Inyanim, Chullin (p 7) s.v. u-mihu.
 Tosafot Chullin 5b applies the dictum to eating ever min ha-hai but not to eating otherwise kosher food before kiddush.
 Gilyonei ha-Shas, Rosh ha-Shanah 15b, s.v. bimkom, commenting on Shu”t Halachot Ketanot (1:9), cited in Sefer Tiferet Yosef (R. Yosef Engel’s commentary to the Torah), Toldot, footnote 23.