Do not knead matza dough with warm water — even if only heated by the sun. (ShA3)
Water drawn from wells, springs, or rivers is warm and must cool down overnight. This is called ‘leena’. (ShA1)
Lechatchila, draw the water after shkia and before tzais hakochavim. This way an entire night can work to cool off the water. (MB5)
The custom is to use new earthenware vessels to draw and store the water. Never use copper vessels — they tend to keep the water warm. (Rama1 — MB25)
When you draw the water, announce ‘L’shaym matzos mitzva’. (MB23)
Avoid putting your hand into the water — hands are hot. (MB20)
Drawing water for matzos mitzva should not be done by a gentile. (Rama1)
If the night is warm, keep the water in a cool cellar or inside a house. If it is a cold night, leave it out in the air. Make sure it is out of the sunlight by the morning. Always cover the water so that no chometz falls in. (ShA1 — MB7,9,12)
Rain water collected from the air does not require leena. (MB28)
The custom is not to add any salt nor spices to the matza dough. These ingredients can speed up the leavening process. (ShA5,6)
