Is white water due to chlorine considered purifying water (ṭahūr), and does its ruling change after its color disappears with storage? And is water from which the smell of sewage emanates considered impure (najas)?

The majority of scholars hold that water altered by pure substances is not sufficient for purification. However, water altered by chlorine or by substances difficult to protect it from is permissible for use according to some scholars. As for a change in the water's smell due to sewage water, if it is merely a suspicion or due to proximity, the water remains pure. But if the water is certainly altered by mixing with sewage water, then it has become impure, and purification with it is not valid, nor is it permissible to use it for other purposes. It is not obligatory to ascertain the safety of water based merely on suspicion; the fundamental principle regarding water is purity until its alteration is proven.