Answered by Shaykh Faraz Rabbani
Question: 1. I was of the understanding that if the fecal matter were to leave the orifice (a dirham or more, something like that) then wiping alone isn’t enough? 2: If one is caught in the situation where he has to defecate at school or some public area where there is no bidet system then does wet toilet paper have the same effect as using water (that is will you fulfill the sunnah) or must you have running water? Furthermore, if the aforementioned is true (about having to use water if it is leaves the orifice) then does this wet toilet paper fulfill the requirement or should one search for a cup?
Answer: Walaikum assalam,
If the filth goes beyond the point of exiting and that which is immediately around it, then that which is beyond this needs to be washed, not wiped.
If the amount that goes beyond the abovementioned area is more than the extent of one’s inner palm (by estimation) if light or 5g if heavy, then one’s prayer would not be valid unless it is has been removed.
If less than this amount, it is recommended to remove the filth, but one’s prayer would be valid if it were not.
Note that the amount at the point of exiting and that which is immediately around it is not considered in the “amount that goes beyond”.
As for using wet toilet paper, this is a problem because it spreads filth, and does not fulfill the condition of “stones” or toilet paper. You can wet toilet paper and squeeze it onto the area, though… But get a cup. Or, just wipe.
Also see: Can one use both toilet paper and water?