What is the ruling on water exceeding two Qullahs when touched by impurity without causing a change in characteristics?
Chapter on what purification is achieved with regarding water
Al-Mughni
Book of Purification
Primary text
There is no difference of opinion within the school that water exceeding two Qullahs remains pure if an impurity falls into it, provided the water's characteristics are not altered, and the impurity is not urine or feces. This position is attributed to Ibn 'Umar, Sa'id ibn Jubayr, Mujahid, and is the view of Al-Shafi'i and those who hold that small amounts are only defiled by change.
Supporting text
This is supported by the Hadith of the Well of Budha'ah, which concerns water where filth and dog carcasses were thrown, yet the Prophet (peace be upon him) declared it purifying, and the well's size was estimated to be less than two Qullahs, or at least comparable to it.