RV Water Sanitizing Tip
If you notice a stale odor when using water from the fresh water tank, this indicates that water was left in the system for quite some time and has grown stagnant.
The best thing to do when this happens is to sanitize the entire water system. First drain all of the water out of the system, and then close all of the drains.
Take one cup of household bleach for every 15 gallons of water that your fresh water tank holds. Mix the bleach in one gallon of water and pour it into the fresh water tank. Fill the fresh water tank with potable water. Turn the water pump on and open all faucets, one at a time, and run water until you smell the bleach. If possible drive or tow the RV to assist in cleaning the entire fresh water tank.
Let it sit for twelve hours and then drain the entire system. Refill the fresh water tank and run water throughout the system (every tap) until you no longer smell the bleach at that location. It may be necessary to repeat this more than once. When you no longer smell bleach, the system is sanitized.
This tip contributed by Mark Polk at RV Education 101
Another good Tip ...
Many people think that using hot water with chlorine bleach will make their system even safer. Using hot water will actually reduce the effect of sterilizing the system since the chlorine evaporates quickly when it is exposed to heat. Always use cold water only.
RV Sales Consultant