Sanitizing fresh water system

I would recommend that you go to a swimming pool supply place and/or a Home Depot store and buy a swimming pool test kit. Once you get it and figure out how to test for chlorine residual, shoot for 1ppm free available chlorine residual which is the same as the recommended amount in pool water. Water from public water sources,campgrounds, state parks have chlorine residual that varies a lot and cannot be counted on to do proper disinfecting of your water. At the very least, use the test kit to check the public water source for chlorine residual. I can almost guarantee that it will not have enough to disinfect your rv system.