What causes a toilet to keep running?
Toilets run because inside of the tank, there is a pipe which lets water go into the toilet bowl when it is flushed. Covering that pipe is normally a rubber flange that gets lifted up by a little chain when you flush. If that rubber flap doesn’t go all the way back down and completely seal the pipe the toilet will keep running. So either the chain is keeping the flap from going all the way down or the flap is not making a complete seal. Easiest fix is put in a new one, costs like 10 dollars and the guys at home depot can show you on the model toilet there.
