Other important notes regarding filth

• If one cannot find clothes without an amount of filth that invalidates the prayer, one prays in those clothes.
• If some clothing had filth on it, but the place of the filth was forgotten and part of the clothing was washed in water without investigation, then the clothing is considered pure. However, if the trace of the filth appeared later, then one must remove the filth and repeat the prayers.
• If one has several containers of water and knows that some of them have filthy water, but not which one, then:
1. If most of them have pure water one makes some effort in deciding which one has pure water, and takes ablution from the water one thinks is pure
2. If half of the containers or more of them have filthy water, then one cannot go by what one thinks for ablution at all, but one can do this for drinking.
• If one knows that some pieces of clothing mixed together have filth on them, one makes an effort to find out which ones, and then prays in the others. This is irrespective of the proportion of clothes with filth -- unlike the case of water containers.
• If one has 3 containers of water, one unknown of which is filth and three men thought (after an effort) a different container to have pure water, then their prayers are correct if they pray single.
• If a man took a complete ablution from two different containers, one unknown of which has filth, without trying to find out which one has filth, then his prayer is correct if he wiped his head in 2 different places. This is if there is no other water available.