Germ Free Water...
It is not uncommon for RV owners to complain of bad water. The first sign of a contaminated water system is usually a bad taste, followed by strange orders emanating from the water supply. Bacteria may have built up in the water tank, especially if the water tank's supply has not been used frequently and has not been replenished with fresh, clean water on a regular basis. When a rig comes out of storage or is being used extensively on a city-water connection, the tank and entire water system should be sanitized before use. Some of the bacterial buildup can cause serious illness; so don't take chances!
Drain the water tank completely, then refill halfway with clean, fresh water.
Mix 1/4 cup of household chlorine bleach for every 15 gallons of tank capacity in a container with a gallon or two of clean water.
Pour this mixture into the water tank. If your RV has a tank fill valve that comes from the city water connection, the mixture can be poured into the hose, or if you use a canister water filter you can remove the filter cartridge and pour the chlorine into it.
Top off the water tank with fresh water.
Pump water through each faucet so that all the lines are filled with the water/bleach. You can easily smell the chlorine odor when it reaches each location.
The hot-water tank holds at least 6 gallons of water. Run the hot-water faucets until this much solution has passed to insure that the old water has been purged from the hot-water tank, and it is now filled with the water/bleach solution from the water tank.
Let the water stand for two or more hours.
Drain the entire water system, and don't forget to drain the water heater.
To remove the bleach odor and taste, mix 1/2 cup of baking soda with a gallon of water and pour into the freshwater tank.
Fill the tank completely and pump this solution through the water heater and the rest of the water lines. Driving the rig around the block will slosh water around and thoroughly clean the tank. Allow it to stand at least two hours.
Drain the entire system and refill with fresh, clean water. Once again pump the water completely through the entire plumbing system.