Q&A: Water Left Overnight
Originally published:
This is an English translation (via GPT-5.4). Read the original Hebrew version.
Water Left Overnight
Question
Hello Rabbi,
For baking matzot, water left overnight is required, and it is explained that the reason is so that the water will be cool.
But I don’t understand that, because spring water and well water are colder.
Answer
I just saw that Rabbi Melamed writes that there was a concern that if they took water from a spring, it might warm up. That can happen sometimes, and therefore they instituted the use of water left overnight. I think that since this is a rabbinic decree, and its rationale has not entirely fallen away, ideally one should use such water; but if you don’t have it, use other cold water.