The Kitáb-i-Aqdas - The Most Holy Book
Index term: definition, under pure; Water
Question: Concerning pure water, and the point at which it is considered used.
Answer: Small quantities of water, such as one cupful, or even two or three, must be considered used after a single washing of the face and hands. But a kurr [this refers to a volume of approximately one half of a cubic metre] or more of water remaineth unchanged after one or two washings of the face, and there is no objection to its use unless it is altered in one of the three ways [colour, taste and smell], for example its colour is changed, in which case it should be looked upon as used.