“ H2o2 is a great sanitizer and it's perfectly safe. ”
Not at the concentrations needed for water purification. 35-50% hydrogen peroxide is a VERY STRONG oxidizer (stronger than chlorine bleach). It can react violently in contact with some organics. 50% can intensify a fire, 70% can actually cause a fire or explosion. You better know what you’re doing if you plan to use any concentration higher than the grocery or drug store version. Even if it says “food grade” on it.
In order to use 3% h2o2 for DISINFECTION, it needs to be used at full strength (undiluted) and remain in contact with the surface for at least 30 minutes. Also, and this is important, the surfaces should be CLEANED first before using h2o2. Since most RV fresh water tanks can’t be cleaned internally, and can’t be completely drained of water, using 3% h2o2 for disinfection will be ineffective. IMHO, of course.
:):)