Is it permissible for a man and his wife to undergo a permanent sterilization procedure (tubal ligation) due to all their children being afflicted with a serious hereditary disease that necessitates periodic blood transfusions, coupled with a high probability of giving birth to an affected child in the future, and their inability to afford early screening or for him to marry another woman?

Water is not rendered impure simply by the entry of an impurity into it. Rather, it becomes impure if its taste, color, or smell changes. However, if it does not change, it remains pure. But it is stipulated that the water should not be little, such that its characteristics do not change when an impurity falls into it. This is estimated at two Qullas according to the Maliki and Hanbali schools of thought.