You’ll have answers all over the board. People commonly use bleach at 1 teaspoon per gallon. If you have an aluminum tank, some people recommend using a non-chlorinated disinfectant.
Some folks even go as far as sending a sample into a laboratory and testing for “drinking water standards”.
Should you have aluminum tanks, like I have in my GB42, testing for metals could be on your list also. I tested for metals and determined that dissolved aluminum was above USEPA drinking water standards and I made a decision not to actively drink from the tanks. However, I wash dishes, shower, etc. with the water.