Ruling when tahur water cannot be told apart from impure water
When tahur water cannot be told from impure water, does one weigh the signs and choose, leave both and perform tayammum, or purify from each and repeat the prayer?
When tahur water cannot be told from impure water, one weighs the signs for purification and drinking if the greater part is pure; if the two are equal, one performs tayammum.
When tahur water cannot be told from water that is impure or made impure, he performs wudu from each vessel and prays after it, praying as many times as there are impure vessels plus one; he does not weigh the signs.
One weighs the signs between the two vessels and purifies himself with the one he judges most likely to be pure; he is not obliged to pour the other away.
Using the two indistinguishable vessels is forbidden and he does not weigh probabilities between them, so he performs tayammum, and neither pouring them out nor mixing them is a condition; but if the pure water reaches two qullas and they can be mixed in a vessel that holds them, mixing and using it becomes obligatory.