Originally Posted by 4Fun
What quantity of hydrogen peroxide would you add to an 80 gallon water tank to sanitize it?
The rule of thumb for hydrogen peroxide is 1 oz of peroxide for each 10 gallons of water. It leaves no after taste at all. You would do the same as with the chlorine -- fill the tank with the required amount of water / peroxide mixture and let set for 24 hours after running all of the faucets in the MH to make sure that the mixture gets into all of your water lines. then drain the tanks and refill with water -- no need to flush out the peroxide mixture in the lines.
If you have an external water filter like I do, what I do to get the peroxide into the water tank is to take out the filter and pour the peroxide into the filter container, hook it up like I would to normally fill with water and turn it on and fill the water tank. As the water flows through the filter body, it will pick up the peroxide and mix with the water as it fills.
Like others have said there has to be drain valves. Where you see the lines coming out of the bottom of the coach, look in the compartment where the drain lines come from -- there may be small valves built into the lines inside the compartment -- usually white plastic valves. My main dump is a large 1 1/2 inch pipe and it has the same type of pull handle that you use to dump the black and grey tanks --- it is also located in the same compartment as the black and grey tank dump valves.