Sanitize or replace old camper fresh water holding tank?

Drain the tank, fill about 3/4 full with fresh water and a gallon of bleach. Drive around for about a half and hour, then turn on all fresh water valves to empty the FW tank into the GW tank. Then drive around some more to sanitize the GW tank. Fill and drain the FW tank a couple of times and then don't drink from it until the smell is gone.