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By Rabbi Dovid Cohen, Administrative Rabbinic Coordinator

Q. My chavrusa challenged me to think of something that this column would be unable to find a kashrus issue with. I said it’s easy: there can’t possibly be anything wrong with plain water, so, please just confirm that for me. 

A. I’ll assume you mean water that’s not flavored, has no additives, wasn’t pasteurized on non-kosher equipment, and isn’t from a city with insects in their water. If so, then on a retail level you’d be right. But in factories things are a bit more complicated, as I’ll illustrate for you.

When a company “concentrates” or condenses juice, milk, soup, or any other liquid, what they’re doing is boiling out most of the water to leave behind the flavorful core. Companies make tremendous efforts to be efficient, and one way to do that is to reuse everything and anything that might have value. Well, the water vapor boiling out of chicken soup (or anything else) is hot and is also “free” water, so many companies will capture that vapor and use it elsewhere in the factory for cooking or cleaning. That water has the same kashrus status as whatever it came from, so if it came from milk, it’s dairy, and if it came from treif soup or stam yayin grape, juice then it’s not kosher, and anything made with that water (or any equipment cleaned with it) will have the same status.

A similar thing can occur in vinegar manufacturing plants, but in somewhat the opposite manner. Vinegar companies concentrate their products (for future industrial use) by freezing it, and if that is done for non-kosher wine vinegar (stam yayin) the leftover water is treif. And the hashgachah must make sure the factory doesn’t use that water when they produce their kosher white distilled vinegar. Another issue for vinegar companies is that vinegar has a very strong odor. Some companies “scrub” (clean) the air leaving their plant to prevent the odor from escaping and bothering neighbors or harming the environment. Scrubbing is done with water, and, once again, if there is non-kosher vinegar in the factory (as is typical) the scrubber water is treif.

Lastly, the process of distilling alcohol is essentially a way to boil the alcohol out of the original wort to make a beverage with a higher alcohol content than would happen naturally. The water left behind still has plenty of flavor in it, and whisky companies might choose to use it in a future mash (mix of grains and water). This means that even if a whisky is made from 100% non-chametz grains, it may contain a high percentage of chametz…in the form of the water used; therefore, one would have to dispose of it or sell it before Pesach.

So, although I sort of found kashrus issues with water, I applaud your taking up the challenge and wish you continued hatzlacha in your creative thinking.

This article first appeared in the Let’s Talk Kashrus column, Yated Ne’eman, April 28, 2023.