804. Baking Matzah on Erev Pesach

113:8 The very scrupulous bake the matzah for the mitzvah on erev Pesach after midday, which was the time when the Pesach sacrifice was brought. Since this is after the time when chometz is forbidden, it is advisable for one to specifically nullify the crumbs and to say in a language that he understands: “Any crumbs that fall while kneading and preparing, and also any dough that sticks to the utensils, I nullify and make ownerless.”

113:9 The water used to wash the utensils must be poured out in a place where it can flow away; it may not be poured on a stone floor so that it may quickly be absorbed into the ground. The reason for this is a concern that if one pours it a place where it cannot flow away or on a stone floor, then the water may collect in one place and become chometz before it is absorbed by the ground, causing him to be in possession of chometz. (One may pour the water in the public domain in any event, though some are stringent – Mishnah Brurah 459:30.)