I have to boil it and then run it through a Brita filter. If I filter straight from the tap, I am guaranteed to get diarrhoea.
Note that I am generally not weak stomached as I’ve eaten stuff that has given others food poisoning before and either nothing happened or I was in an overall much better condition than them. I’ve never had stomach problems in my entire life until I lived here. I also have friends (local and foreign) who can’t drink the tap water without getting ill.