The flour for the matzos should be kneaded only with water that has stayed overnight,1 that is to say, it should be drawn during twilight, and left standing overnight. Even if the night is longer than twelve hours, it is forbidden to use it for kneading until daylight, and if the night is short and there are no twelve hours until daylight, we must wait until twelve hours will have passed from the time it has been drawn. Ordinary people are accustomed to begin kneading as soon as it grows light, with water that stayed overnight, even though, as yet twelve hours have not passed. Although there are some authorities who permit this, most of the authorities take the more stringent view. It is necessary, therefore, to be watchful in this matter.


If you are unable to estimate the exact time of twilight, you may draw water a little earlier, provided you do not draw it before sunset.2 It is the custom to strain the water and to cover it, and it must be placed in a cool place. When bringing the water into the house in the morning, you must be careful to keep it out of the sun.


You are permitted to draw enough water at one time to last for several days, but the proper way of fulfilling the mitzvah is to draw water daily for the needs of that day. It is the custom not to draw water in an old earthen vessel, even though it is used only for Pesach, unless it is glazed, for the use of an old unglazed vessel cannot be considered an enhancement of the mitzvah. This custom should not be changed.


Rivers in the month of Nissan are generally cooler than wells. You should, therefore, draw water from a river. Sometimes, however, the rivers are swollen from the melting snow and the water is not so cold; it is then preferable to draw water from a well.


The water should not be drawn by a non-Jew, but by a Jew.3


You should not put the water in a vessel that has contained honey or fruit juice, unless it has been kashered with boiling water. You surely should avoid placing the water into a vessel that had contained food with a sharp taste, even if it was not chametz, because on account of the sharpness, the dough will rise faster, and even kashering with boiling water will be of no use in such a case. Neither should you put the water into a copper vessel,4 because it does not keep it as cool as other vessels.


If you notice that the water kept overnight is not sufficient, you may add other water,5 provided most of the water is that which stayed overnight. Initially, it is best that two thirds of the total should consist of the water that stayed overnight. If possible, try to draw the added water from a pump or a covered well, where the sun does not reach.


If the matzah is baked on Sunday, the water must be drawn on Thursday evening, because on Friday it is impossible to fix the exact time of twilight. In an extreme circumstance, if the water was not drawn on Thursday, it should be drawn on Friday after the Minchah service, or on Shabbos by a non-Jew.


The water held overnight should not be poured out on account of a death that has occurred, or on account of the vernal equinox, because it is said, "He who keeps the commandment shall know no evil thing" (Ecclesiastes 8:5). Nevertheless, if you know that the vernal equinox will occur, you should put into the water a small, clean piece of metal, something like a needle attached to a thread, so that afterwards you will not have to put your hands into the water to get it out, but you will be able to pull it out by the thread.6