This question already has an answer here:

There is a not-uncommon minhag, primarily in chassidic circles called 'gebrokts' where matza is not allowed to come into contact with water during Pesach. What is the earliest source for this custom and it's meaning?

merged by msh210 Mar 28 '13 at 21:29

This question was merged with Chabad custom of not allowing water to touch matzah on Pesach because it is an exact duplicate of that question.