Islamic scholars explain this ruling based on authentic hadith. The Prophet ﷺ said that when water reaches two qullah, nothing can make it impure. He ﷺ also said that water is pure and nothing makes it impure unless its taste, smell, or color changes.
From these narrations, Islamic scholars derived a clear fatwa. If impurity falls into standing water, the amount of water is checked first. If the water is less than two qullah, it becomes impure even if there is no visible change. If the water is two qullah or more, it only becomes impure when there is a change in its color, smell, or taste due to the impurity.
Islamic scholars defined two qullah as about 192 liters of water or more. This ruling is agreed upon regarding large amounts of water when change occurs, as mentioned in classical fiqh books. This Islamic ruling is based strictly on hadith and scholarly consensus.
