Someone asked, "Messenger of Allah, do you perform ablution from the well of Budaah, when it is a well into which the flesh of dogs, menstrual rags, and putrid matter are thrown?"He replied, "Water is pure, nothing makes it impure."
أخبرنا هارون بن عبد الله قال حدثنا أبو أسامة قال حدثنا الوليد بن كثير قال حدثنا محمد بن كعب القرظي عن عبيد الله بن عبد الرحمن بن رافع
قيل يا رسول الله أتتوضأ من بئر بضاعة وهي بئر يطرح فيها لحوم الكلاب والحيض والنتن فقال الماء طهور لا ينجسه شيء
[The isnad is hasan] Abu Dawud narrated it in the Book of Purification, chapter on what has been said about the well of Budaah, hadith no. 66, 67, and Tirmidhi in the Book of Purification, chapter on what has been said, that water is not rendered impure by anything, hadith no. 66, from the hadith of Abu Usama with this same wording, and Tirmidhi said, "Hasan," and Ahmad, Yahya bin Main, Hakim, and others graded it sahih (Talkhis Habir 1/13, 14).