We use household bleach (no “fruit” flavors ;)), each year prior to use. We “DO” use our onboard fresh water......and have since the beginning of our Rv’ing ( early 1970’s). If your system is cleaned and you put quality water in the tank...there is absolutely “no” logical reason not to use that water for drinking/cooking! I guess if your RV only sees campground use .....then perhaps using the campground water is great. However, there’s is always the possibility that campground water may not be up to EPA standards, or as “sanitary” as your fresh tank water! Useless you know the quality of the campground water....it’s a “roll of the dice”! memtb