Ask the Rov: How much water can I add to wine for kiddush?
By Rabbi Chaim Hillel Raskin – Rov of Anash in Petach Tikvah
Wine in Talmudic times was more potent, so the Mechaber writes that it was sufficient as long as one-quarter of the mixture was wine, and the bracha remains hagafen. Yet, he notes, wines today are typically less strong, and a greater percentage of wine is required, with each location following its custom. The Rama comments that one-sixth (approx. 17%) of wine is sufficient as long as the mixture tastes like wine.1
Many, including the Alter Rebbe, understand the Mechaber to be discussing how much water may be added to wine sediment to create reconstituted wine, while the Rama refers to diluting regular wine.2 The 17 percent mentioned by the Rama can be understood to be regardless of local custom, while some explain to be adding to the local practice but not allowing more dilution.3
What about today?
The Kaf Hachaim writes that besides tasting like wine, contemporary wine, which is weak, must have a majority of wine against the water, and this is the accepted halacha among Sefardim.4 Some quote a Chabad tradition only allowing dilution up to a third of water, and some Kashrus agencies follow this given that we don’t have a shortage of wine.5 Since many wines today already have water added during production, one would need to ascertain how much was added before adding more.6
Others, however, follow the Rama, and say that today as well, the primary criterion is for the mixture to still taste like wine.7
R. Shlomo Zalman Auerbach writes that one who is stringent may hear kiddush from someone making kiddush on highly diluted wine, though he recites shehakol to drink from it.8
After drinking from a cup of wine, the leftover wine is considered “blemished” (pagum) and cannot be used for any kos shel bracha (kiddush, havdala, zimun). To rectify its impairment, one must pour any amount of unblemished wine or water into the cup. Even if pouring back into the bottle — when some consider the blemished wine to become bottel — the Alter Rebbe advises adding some good wine to the cup first, and only then pouring it back into the bottle.9
Today when wines are weak and don’t require additional water, some argue that water should only be used to fix blemished wine when good wine isn’t available.10 However, the Alter Rebbe rules that one may rectify the blemish with a bit of water as long as it doesn’t spoil the wine and the water itself isn’t pagum.11
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From The Weekly Farbrengen by Merkaz Anash