Abu Dawud Book 001, Hadith Number 0067.
Chapter : On the well called budaah.
Narated By Abu Sa'id al-Khudri : I heard that the people asked the Prophet of Allah (pbuh): Water is brought for you from the well of Buda'ah. It is a well in which dead dogs, menstrual clothes and excrement of people are thrown. The Messenger of Allah (pbuh) replied: Verily water is pure and is not defiled by anything.