Do we wait for water to become pure on its own, or do we add water to it to purify it?

Question : We take, O Shaykh, the water that has increased until the change is removed by itself, and between his saying that the kidneys share in the increase until the water becomes much, how is that? Is there no contradiction or conflict between his saying that if the water increases and the impurity is removed by itself, the water is much, yes, or if we add the condition of adding the kidneys, the kidneys?

Answer : Because perhaps one does not wait until the change is removed by itself, because the change is not removed by itself immediately, so perhaps he does not wait, saying: If you do not want to wait, add to it.