There is a safe level of chlorine one can use to sweeten the water system. I don't recall the exact solution but I bet an on-line search will provide a safe chlorine dilution based on tank size.
In my RV it is a springtime ritual after de-winterizing to flush a heavy chlorine solution through the lines. This is a situation where I do not use the tank, so I am not too worried about too much chlorine, as it is quickly removed from the lines after sitting for an hour or so....
That does it for me in the RV, basically just once a year.
If I was using the fresh water tank I would likely add a tiny amount of chlorine to every tank, based on research I recommend above.