Completely drain the RV's water tank and refill with clean water.
Add 4 tsp. of liquid soap for every 10 gallons that the tank holds.
Turn on all faucets and run the soap solution through all of the faucets and holding tanks for several minutes.
Turn off the faucets. If possible, drive or tow the RV a short distance to move the water around inside the tanks before draining the soap solution.
Refill the tanks with clean water and run it through all of the faucets until there is no more sign of soapy residue.
Add clean water to the tank until it is mostly full, leaving enough room for an additional gallon to be added.
Combine one gallon of water with 1/4 cup of liquid chlorine bleach per every 15 gallons that the tank holds. Add this solution to the tank.
Turn on each faucet, one at a time, and run the chlorinated water through it until you can smell the chlorine, about two minutes.
Leave the remaining chlorine solution in the tank and add clean water until the tank is full. Leave it to sit for a minimum of one hour, or overnight if possible, before driving or towing the RV a short distance to move the solution around inside the tank.
Drain the chlorine solution and refill the tank with fresh water. Turn on each faucet and let the tank completely run out to flush the system. Repeat until you can no longer smell the chlorine.
Refill the tank with fresh water.
Add 1 tsp. of liquid chlorine bleach to the tank for every 10 gallons of water that it holds. If filling the RV's water tank from an already chlorinated source, such as city tap water, it is safe to skip this step.
Repeat step 2 each time you refill your water tank while traveling or camping.
