Thursday, June 1, 2023


RV fresh water chlorination


gary-736Dear Gary,
The water in our RV had a bad odor, a musty smell, so we added some Clorox to the tank and let it set awhile. Now we cannot get the Clorox taste out. What do you suggest we add to get rid of the Clorox taste? —Stacey

Dear Stacey,
Foul or stale-tasting water can not only ruin a vacation but may even be harmful. But the pungent flavor of Clorox might even be worse — like drinking water from a swimming pool! There is usually sufficient chlorine in most city water supply systems for safe storage in an RV, but if foul-tasting water persists, it may be necessary to treat the fresh water system from scratch. Of course, the fresh water container only stores the quality of water put in there, so be sure to taste it prior to filling up. Here’s the approved method of chlorinating the entire fresh water system:
1. Drain and flush the fresh water tank; leave empty. Be sure the water heater is not in the bypass mode.
2. Mix 1/4 cup of liquid household bleach (sodium hypochlorite) solution with one gallon of fresh water. (A clean 1-gallon milk bottle works great for this).
3. Pour directly into the fresh water tank.
4. Pour in one gallon of the chlorine/water solution for every 15 gallons of fresh water tank capacity.
5. Top off the tank with fresh water.
6. Remove or bypass any water purification equipment and/or filtering cartridges.
7. Turn on the water pump and open every faucet in the RV, including exterior faucets or shower heads.
8. 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 a mild odor of chlorine is present at every fixture.
9. 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.
10. Close all the faucets and turn off the water pump.
11. Allow the system to stand for four hours. This will chlorinate and disinfect the system, including 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).
12. At four hours, drain and flush the system with fresh water once again.

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 stand for at least one to two hours. Do not allow the chlorinated solution to sit longer than four hours in the fresh water system to avoid damage to some delicate plumbing components found in some water pumps. This is the approved method to be sure bacteria are effectively eliminated. This process should be performed after any period of nonuse or storage, or whenever stale or distasteful water is experienced. 

Since you’ve already put Clorox in the system, you may have used too much. Just keep flushing it out. Fill the tank, pump it through, drain and refill. If the heavy bleach concentration has permeated the plastic piping severely, you may have to keep pumping fresh water throughout the entire system to be sure all the bleach is eliminated. Eventually the odor of the Clorox will subside.

There are aftermarket fresh water additives that can be added to the fresh water tank, but those that I’ve tested consist primarily of chlorine elements and I don’t think you need any more of that. I’ve also heard of adding distilled vinegar to the water system. Add about 1 quart for every 5 gallons of water capacity, and pump it through the system as you do with chlorine. Let it stand in the system overnight and, as with chlorine, fully flush the system until you are satisfied with the taste and smell. I’ve not tested this method personally, but if the Clorox taste still remains, it just may be a viable alternative method.

Read more from Gary Bunzer at the See Gary’s videos about RV repair and maintenance.




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6 years ago

Dissolving baking soda and running through the system works too. We have done that a few times.

6 years ago

Use 2 cups of white vinegar along with a full tank of water in your fresh water tank to neutralize the bleach scent. No need to let it soak just run it thru the entire system for a few minutes opening all faucets. After doing this for a few minutes just drain the fresh water tank and replace with clean water. No more bleach scent, and no residual vinegar scent either.

Linda H
6 years ago

Vinegar will work to clear out the Clorox taste and smell. We always flush out tank with the bleach solution first, vinegar second. Never a problem with any leftover tastes/odors.

6 years ago

Hi Gary,
I have a 1988 Texson truck camper that I have use all these years. I have only used Vinegar in my holding tank to clean it at the beginning and end of the season. It works great. There may be a little taste of vinegar at first but it goes away.

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