Making Seltzer on Shabbos

Q. It permissible to make seltzer water on Shabbos?

A. Seltzer is made by injecting CO2 into water. When this is done, the water immediately begins bubbling. Are these bubbles included in the prohibition of molid (creating something new)? The Ben Ish Chai (Rav Poalim OC 1:18) writes that one may make seltzer on Shabbos. He writes that since one does not actively make the water bubble, but rather by adding the carbonating ingredients to the water, it will begin to bubble on its own, it is permitted. This is comparable to melting ice by placing it into water. Although one may not rub ice to make it melt, one may allow ice to melt on its own by placing it into water. The same can be said about bubbles. When one injects the CO2 into the water, the bubbles will come out on their own. However other poskim such as Chelkas Yaakov (OC 134) were strict based on “uvda d’chol” (looks like a melacha). But the more common custom is to allow. This was also the ruling of Rav Ovadya Yosef zt”l (Yebia Omer OC 3:21), Shemiras Shabbos K’Hilchaso (11:36) and many other poskim.

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The Gerald & Karin Feldhamer OU Kosher Halacha Yomis is dedicated to the memory of Rav Yisroel Belsky, zt"l, who served as halachic consultant for OU Kosher for more than 28 years; many of the responses in Halacha Yomis are based on the rulings of Rabbi Belsky. Subscribe to the Halacha Yomis daily email here.