What is the ruling when used water mixes with other used water?
Chapter on what purification is achieved with regarding water
Al-Mughni
Book of Purification
Primary text
If used water combines with other used water and the total volume does not reach two Qullahs, the mixture remains subject to the prohibition (of purification). If the total volume reaches two Qullahs, there are two established opinions regarding its status, based on the interpretation of the Hadith concerning the two Qullah threshold.