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Thursday, January 18, 2001

Chlorinating the Fresh Water System


1. Drain and flush the fresh water tank; leave empty.

2. Using a mix ratio of 1/4-cup of liquid household bleach (sodium hypochlorite) with one gallon of fresh water, make up one gallon of chlorine-water solution for every 15 gallons of fresh water tank capacity.

3. Pour the chlorine-water solution directly into the fresh water tank through the gravity fill. Note: If the RV is not equipped with a gravity fill for the fresh water tank, use a funnel to pour each gallon of the mixture directly into the fresh water hose prior to connecting it to the city water source.

4. Top off the tank with fresh water.

5. Remove or bypass any water purification equipment and/or filtering cartridges.

6. Turn on the water pump and open every faucet in the RV, including the exterior faucets and showerheads.

7. Allow the solution to pump through the system to the toilet, through the water heater, and to every hot and cold faucet at each sink until the distinct odor of chlorine is present at every fixture. (You can open one faucet at a time or all at once.)

8. At the city water inlet, using the eraser end of a pencil, push in on the check valve spring, allowing the solution to pump out through the city water inlet until the chlorine odor is detected in the discharge.

9. Close all the faucets and turn off the water pump.

10. Allow the chlorinated water to remain in the system for four hours. This should chlorinate and disinfect the fresh water tank, the water heater, the faucets, the complete piping system, and all fittings to a residual level of 50 ppm (parts per million).

11. Once you reach four hours, drain and flush the system once again and top off the water tank with fresh water.

To avoid damage to delicate plumbing components found in some water pumps, do not allow the chlorinated solution to sit longer than four hours in the fresh water system. If 100 ppm residual concentration is required or desired, use 1/2-cup of bleach instead of 1/4-cup with each gallon of the solution and let it stand for one to two hours.

If the odor of the chlorine is still very strong after you have drained and flushed the system, drain, flush, and refill the tank again until you are satisfied. This process should be performed after any extended period of nonuse, such as after storage; whenever stale or distasteful water is experienced; or at least once per camping season.


In all instances, every effort is made to ensure the correctness of all content on the RV Doctor Website. It is imperative that if you choose to follow any instructions or procedures outlined on any page of this website, you must first satisfy yourself thoroughly that neither personal nor product safety will be compromised or jeopardized.

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If you are in doubt or do not feel comfortable about a procedure, do not continue. Simply call your local RV service facility and make an appointment with them. The advice, recommendations and procedures offered by the RV Doctor are solely those of Gary. They do not necessarily reflect the opinions, procedures and recommendations of our sponsors or advertisers.