Trust me, I know way to much about the nasty stuff that likes to grow in wet, dark places. I am curious, did your RV come with a schedule for cleaning you potable water tank? And how vigilant are you about flushing and disinfecting your water tanks. Thanks.
It's a 'holding' tank and a breeding ground for bacteria. I take no chances. Bacteria can enter your body via the nose from water droplets when showering also.
I bleach out the tank and lines often. I do not drink or cook with the water from the holding tank.
Filling a holding tank with chlorinated city water does not have a concentration high enough to kill bacteria in a holding tank. The choline was added at the filtration plant to kill bacteria before you receive it at a residential faucet and all that is left is the 'smell' of the chlorine.
Will you up and die from the bacteria? No. But that diarrhea you thought was from too much beer and chili dogs from last nights cook out could actually have been from the bacteria in the water in the holding tank! :B