Instead I will just keep treating my system before each season and if the water is stagnant or unchlorinated
I must ad,I am basing my experience using city water that has been treated and chlorinated...Nothing else..
Once we were running out of water way back in the hills and we decided to take some water that was coming straight out of the mountain and had been tested by some backcountry homeowners..We have drank this water for years..
So I transported water to my TT using 6 gallon water containers,then dumped it in the tank via the spicket and nozzle...All was good until about a two weeks later..It smelled like rotten eggs..Yuck...So I did sterilize the tanks and lines twice with bleach..No issues since..
It has to be city/treated water to last in an RV tank.