Ruling on purifying water that has become impure and the clearing of its alteration
How does impure water become pure again: by adding tahur water, by drawing it off, or by the alteration clearing on its own?
Impure water is purified by drawing off the amount the Law specifies in the case of wells, or by pouring tahur water over it until every trace of the impurity is gone.
Impure water is purified by pouring unrestricted (mutlaq) water over it until its alteration clears; it is not purified by the alteration clearing on its own or by standing for a long time.
Much impure water becomes pure when its alteration clears by itself or through added tahur water; little water becomes pure by adding until it reaches two qullahs unaltered.
Much water becomes pure when its alteration clears by itself, by adding a large quantity of tahur water, or by drawing off so that a large unaltered quantity remains; little water becomes pure by adding a large quantity of tahur water to it, provided its alteration, if any, clears.