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NY Times . November 7, 2004  . "The Water's Fine, but Is It Kosher" by Joseph Berger

General Information . Orthodox Union . "NYC Water"



November 7, 2004

The Water's Fine, but Is It Kosher?



When rabbis in Brooklyn spotted a tiny crustacean swimming in New York City's tap water last spring, the ensuing debate about whether it rendered the city's water unkosher seemed like an amusing, but esoteric dispute in a particularly exacting Jewish enclave.

But in the months since, the discovery has changed the daily lives of tens of thousands of Orthodox Jews across the city. Plumbers in Brooklyn, Manhattan and Queens have been summoned to install water filters - some costing more than $1,000 - and dozens of restaurants have posted signs in their windows trumpeting that they filter their water. As a result, an entirely new standard is being set for what constitutes a kosher kitchen.

"I don't want people in the community to be uncomfortable in my home," said Laurie Tobias Cohen, executive director of the Lower East Side Conservancy, explaining why she put a filter on the faucet of her Washington Heights apartment.

The issue has created the perfect conditions for a Talmudic tempest, allowing rabbis here and in Israel to render sometimes conflicting and paradoxical rulings on whether New York City water is drinkable if it is not filtered. As with the original Talmudic debates, the distinctions rendered for various situations have been super-fine, with clashing judgments on whether unfiltered water can be used to cook, wash dishes, or brush teeth, and whether filtering water on the Sabbath violates an obscure prohibition.

The creature, a crustacean known as a copepod that comes in several species, is found in water all over the world and is perfectly harmless. But it is a distant cousin of the dreaded shrimp and lobster, shellfish whose consumption violates the biblical prohibition against eating water-borne creatures that lack fins and scales.

The prohibition refers only to species that can be seen with the unaided eye - not, say, an amoeba - and the question of whether the copepod is indeed visible is central to the dispute. Some are so small as to be invisible, while others can grow to a millimeter and a half in length, large enough to be seen in water as small white specks.

The tumult is confined largely to New York because it is one of the few cities that is exempt from federal filtering requirements. Boston and Seattle are also exempt, but they have nothing like the city's numbers of Orthodox. In New York City, there are 331,200 Orthodox Jews, a third of the Jewish population, according to a 2002 study done for UJA-Federation of New York.

The sure winners in this theological tizzy are plumbers and water filter entrepreneurs.

"We've had a 500 percent increase in sales," said Houston Tomasz, vice president of Sun Water Systems of Fort Worth, Tex., which manufacturers the Aquasana filter, whose full-house version can cost more than $1,500 installed. "Not everyone was a kosher Jew. When you start talking about visible bugs in water, Jews aren't the only people who care."

In Brooklyn, a landlord started a firm overnight that he called Eshel Filters. In September just before the Sukkot holidays, when many Jews invite neighbors over, the company installed 30 filters a day ranging in cost from $99 to $1,150. Its motto: "The bug stops here."

The controversy is indicative of deepening religious conservatism in the American Orthodox world. William B. Helmreich, a professor of sociology and Judaic studies at the City University of New York Graduate Center, said that "in a society where people feel via the Internet and television their very values are under constant attack, there's a need for people to reassert their level of religiosity, and one way this is done is by discovering new restrictions which give people the opportunity to demonstrate their adherence to their faith."

For generations, the most pious Jews - even revered rabbis like Joseph B. Soloveitchik and Moses Feinstein - drank unfiltered New York water with no evident concern. But six months ago, a group of Brooklyn rabbis were examining some lettuce imported from Israel that was supposed to be bug-free, but which appeared to have insects on its leaves. After an investigation, they determined that the "bugs" had arrived after the lettuce was washed in New York City water, and said that in the right light they could see the telltale specks with their own eyes.

At some point, a delegation of rabbis took a field trip to the city's reservoirs and asked officials some detailed questions about the origins of the water and the copepods. (Of the three reservoir systems, only one - the Croton - is in the process of introducing filtering, with a plant that will cost an estimated $1 billion but will not be completed before 2010.)

The question lingered unresolved by a major communal authority until the Orthodox Union, which certifies as kosher 275,000 products in 68 countries, weighed in last August after checking some water samples.

"When they saw the first sample they didn't feel it reached the threshold of being visible," said Rabbi Menachem Genack, the rabbinic administrator for the Orthodox Union. "What changed people's minds is when they saw a sample taken from a pond and saw them scooting around. Those are beyond the threshold."

The Orthodox Union recommended that restaurants and caterers under its supervision filter their water before using it in drinking and cooking, a policy that quickly was adopted by many homes as well. The policy considered different practical possibilities. Dishes may be washed by hand in unfiltered water, it said, if the dishes are towel dried or left to drip-dry without puddles of water in them.

But it also said water should not be filtered on the Sabbath because one of the 39 varieties of work forbidden by the sages includes "selection," or sifting of food, like separating wheat from the chaff or raisins from a noodle pudding.

The organization issued the policy to make sure even the most stringent consumers would be satisfied that what they were eating was kosher to the highest standards. But a debate continues within its own rabbinical ranks about how the filtering policy should be applied in ordinary homes, and some rabbis have suggested the filtering frenzy may have gone too far.

Rabbi Yisroel Belsky, one of the leaders of Torah Vodaath rabbinical seminary in Brooklyn and an important voice on Orthodox Union kosher matters, said in an interview that there was no requirement to check for things that were impossible to see in the years before microscopes.

"If everybody goes around thinking that whoever doesn't filter water is actually eating things that are treyf," he said, using a Hebrew word for unkosher, "there will probably be all kinds of disputes between individuals and marriage problems that can cause a cleavage."

Many Jews have been left confused. Fran B., a marketing manager for a software firm who asked that her last name be withheld, said she did not want to tear up the granite countertops in her Manhattan apartment to install a filter under the sink, so she lugged bottled water from the supermarket.

"On the one hand, I'm drinking bottled water, but on the other hand I'm eating at friends' houses who have never even heard of this," she said.

Others are perplexed about whether to filter at all, filter on Sabbath, or filter for purposes of cooking, washing dishes or brushing teeth.

"The difference in opinions is driving a lot of people crazy," said Rabbi Ephraim Buchwald, director of the National Jewish Outreach Program in Manhattan, who hauls bottled water to his apartment so he will not have to filter on Sabbath. "You can't imagine what a turmoil it is."

In an article in The Jewish Press, David Berger, a professor of history at the City University Graduate Center and a rabbi, said, "The notion that God would have forbidden something that no one could know about for thousands of years, thus causing wholesale, unavoidable violation of the Torah, offends our deepest instincts about the character of both the Law and its Author."

Rabbi Moshe Dovid Tendler, who is a professor of biology and of Talmudic law at Yeshiva University, said he spotted the telltale specks only after first looking at copepods through a 60-power dissecting microscope.

But having seen them, he said he thought they should be filtered out. Nevertheless, he does not believe the filters should be turned off on Sabbath - Jewish law already allows people to pick algae or other vegetation out of water. And he certainly does not worry about whether pious Jews who drank unfiltered tap water in the past sinned.

"The hidden things belong to God," he said. "We are responsible for what we see. If you don't know about it and don't see it, then it doesn't exist. So those who drank the water before were drinking kosher water."




NYC Water

The following statement is not meant as a Psak for individuals or communities.  Rather it is a statement of OU policy for the restaurants and caterers under its supervision during this interim period while research is still ongoing.

While we share this with the public, we recommend that you speak to your Orthodox Rabbi for his guidance in this, as in all Halachic matters.


Tiny crustaceans called copepods have been found in New York City tap water. The species we are finding primarily is Diacyclops thomasi, along with some Mesocyclops edax and Skistodiaptomus pygmaeus. These tiny crustaceans are ubiquitous in ponds, lakes, and reservoirs. New York City, because of the high quality of its water, is not required by the EPA to mechanically filter its water.  Their appearance in tap water as small white specks may represent a significant kashrus issue.

It is important to note that in some cases, water containing aquatic micro-fauna is permitted for consumption by Halacha. This is determined by several factors, including:

  • Whether or not the organisms came into existence in water contained by vessels, cisterns, wells or still-water enclosures, and other factors (See Talmud Bavli: Chullin 67a, and Shulchan Aruch: Yoreh De'ah: 84:1,2 with commentaries);
         The visibility of the organism to the unaided eye;
         The frequency in which the organisms appear in the water from the tap.

    Some Poskim (rabbinic decisors) believe that one of the above considerations might apply in our case, and rule, therefore, leniently. Many others feel that the prevalence, nature of the water source, and size of the copepods do not allow for a lenient decision. Since this is an issue of a potential Issur d'oraisa (prohibition on a biblical level), we are issuing the following, interim, guidelines to OU certified restaurants and caterers.
  • Tap water in New York City (i.e., the boroughs of Manhattan, Brooklyn, Queens, Bronx and Staten Island) should be filtered before use in drinking, cooking and baking;
  • Products already manufactured may be used, even if made with unfiltered water;
  • The water supply of dishwashers does not require filtering.  Similarly, dishes may be washed by hand in unfiltered water if the dishes are subsequently towel dried, or left to drip-dry without "puddles" of water in them;
  • Water should not be filtered on Shabbat or Yom Tov because of the prohibition of borer (selection).  Rather, filtering should be done before Shabbat and the water should be stored for Shabbat use.  One may, however, filter water for non-food purposes on Shabbat and Yom Tov.
  • Bottled water is permitted for use.

    We have found filters rated at 50 microns to be sufficient.  Most commercial filters are finer (10-15 microns) and will filter out the copepods.  Filters must be maintained or they lose their effectiveness.

The OU continues to evaluate the issues. As new information emerges we will make it available to the public. As in all such cases, individuals should consult with their local Orthodox Rabbi for guidance.

General information phone: 212-613-8241

Orthodox Union 11 Broadway, 14th Floor New York NY, 10004






A common feature uniting all the copepod orders is a single simple eye in the middle of the head, at least in the larval stage. The cephalosome, a shield over the head and some thoracic segments distinguishes the free living forms. Most are very small, less than 1 mm long, but rare oceanic species are over 1 centimetre.

There are several different forms of copepods arranged into ten groups called orders. It is not a simple matter to distinguish the orders of copepods, and impossible without a good microscope. Few biologists attempt to identify copepods beyond the level of order but species diversity has been found by those that have to be very high. Most of the free-living species belong to only three orders. The rest are usually parasitic, some barely recognisable as crustaceans except when larvae.


Free-living copepods will be found only by towing very fine nets, certainly less than quarter-millimetre mesh, through a pond or sea-water, or by washing the fauna off marine algae through a net of this kind. Animals which may appear only as a tiny speck to the naked eye may be copepods but their identity demands most detailed microscopic examination of preserved specimens.

Being so small, free-living copepods can feed only on small food items like bacteria, diatoms or other unicellular forms. Eggs produced by the female copepod are carried in clusters in one or a pair of egg-sacs attached to the base of the abdomen. Females like this are easy to recognise as copepods.


Copepods live throughout all the water masses of the ocean and lakes, on the ocean floor, as well as in association with other animals



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