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Kosher Water

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.

We 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.

We want to make sure even the most stringent consumers would be satisfied that what they were eating was kosher to the highest standards.

To get a certified Kosher Filter please contact REATON at