Thursday, June 8, 2023


My RV’s water pump “cycles” when not in use; dealer says this is normal. Really?

Dear Dave,
My RV’s water pump will kick on for about two seconds once or twice a day when no water is being used. The service repair folks said that was normal. This did not occur in my other RV. Should I be concerned about a slow leak, or is this truly normal? Thank you for your assistance and time. —Cathy, 2023 Chateau 27R 

Dear Cathy,
There is a difference between normal and correct. If there is no leak in the water system, the pump should not “cycle,” and this is not a correct operation. However, there are so many plumbing connections in an RV that could create a slight water leak or allow air into the system. So it could be a long troubleshooting journey for a service center that might not be able to find the problem and fix it, so they can’t get paid.

RV should still be in warranty

Since it is a 2023, it should still be in warranty. Therefore, I would suggest contacting Thor and its Chateau division to get it documented. Hopefully, they will contact the service center, unless they are not a Thor dealer. You don’t typically need a Thor dealer to work on the pump. It should be a Shurflo, Lippert, or other common pump. It would just need to be taken to a service center that is authorized to work on the pump—that is, if it is the pump.

This is where is gets a little fuzzy because if it’s a leak in the plumbing somewhere and not the pump, it would need to be a Thor-authorized warranty center.

The pump is designed to hold pressure and, yes, I have found a few units that will cycle occasionally like yours. However, there is a leak somewhere and it could take quite some time to track it down. That’s probably why they stated it was “normal.”

Bench test the water pump

What I would do first is to take the pump out of the unit and bench test it. We had the same thing happen to a 2003 Winnebago Brave and the owner was positive it was the pump. I pulled the pump, hooked up a 12-volt source and water lines in and out with a 5-gallon pail of water and let it sit for 3 days with no cycling. No, I did not sit there all three days watching it. But I did have it in my shop while working for about 6 hours, so I know it was not the pump. The owner was not convinced, so he bought a new pump and installed it himself, only to have it cycle the same way.

The point is, if you can bench test it, you can isolate if it is the pump or something in the plumbing. If it is the pump, most likely it is something in the rubber diaphragm or a crack in the filter plastic. The diaphragm could just be calcium or lime. Or, since it is a 2023, it is probably plastic shavings from the freshwater tank.

If the pump tests good with no cycling, then it is a leak in the plumbing system downstream that eventually is allowing water to seep out and reduce pressure to the point the pump kicks in. Since it’s typically just a slight leak, like even a drip, it takes a long time between cycles and the pump only kicks on for a quick “parump” to create pressure again.

What to look for

It could be a faucet that is only providing an occasional drip that you would not notice or see in the bowl. Or it could be the shower, either at the shower head or the faucet, which could be hidden behind the shower wall. If you have access to the water pump, follow the lines and inspect every connection. There will be several elbows, “T” connections, and low point drains. I have used pieces of colored construction paper placed underneath these connections as a drip will be enhanced on the paper rather than drying up on the floor or hidden in carpet. Check all water supply lines such as the toilet, water heater, outside shower, and refrigerator ice maker if you have one.

What we found with the Winnebago issue was the city water/freshwater fill valve. When you are connected to city water with a pressurized hose, this valve allows you to fill the freshwater tank by switching the valve and it diverts the water to the tank. We got lucky finding it as I asked my Winnebago contact if he was aware of this. He said that the valve can either get a crack or a leaky connection, which you would never see as it is behind the service panel. I swapped out the valve and the pump sits quiet until someone opens a faucet.


 You might also enjoy this from Dave 

My RV’s water pump is noisy. What can I do?

Dear Dave, 
My RV’s water pump was very noisy so I replaced it with a Quiet Pump, with no change. I still have the water hummer noise. What do you suggest? —Donald, 2019 Greyhawk

Read Dave’s answer.

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

Read more from Dave here


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Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.


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Neal Davis
13 days ago

Thank you, Dave! Your answers are so complete that they are extremely educational even when the problem does not apply (or has not applied) to my rig; thank you!

Thomas D
16 days ago

I’d replace the check valve in the pump. No water leak? Then its just trying to balance pressure. No leak?

Tommy Molnar
16 days ago

Our 2012 Arctic Fox (that we call “Artie”) has occasional ‘Artie farts’ It’s a short brrrt and that’s it. We have never been able to find any leaking water anywhere. We had the same thing with our 97 Nash. Those were called “Nashy farts”. Never could find any leaking water in that trailer either, and we had it for 16 years. I like Bob’s comment below about the water heater. This might explain our problem – if it is a problem.

Jim Johnson
16 days ago

Do you have a grit filter between your fresh water tank and you water pump? My 2017 RV did not. A tiny bit of grit caught in the water pump’s check valve allowed pressure to seep through the pump back into the fresh water tank. Never had another problem after this simple installation.

By the way, install the filter with the bowl up (or at least angled up) rather than down (or angled down). If the bowl is below the horizontal water line, you will have one more winterization chore to remove the bowl to drain it. When up, the water will drain into the pump. The filtration works the same in either orientation. However, when oriented with the bowl up, if you need to clean the filter screen (very rare in my experience), be sure to put either a towel or small shallow catch bowl underneath as you unscrew the bowl as some water might drip.

16 days ago

One other place to look is the water heater. There may be too much air in the tank and when the water cools, the pressure in the tank drops, causing the pump to cycle. Turn off the water heater and allow it to cool. Open the valve until water comes out and close it. Also, it could be the pressure/ temperature valve itself dripping.

Jim Johnson
16 days ago

Winterization hint: If you have a single water entry that is switchable between city pressure and filling the fresh water tank, use an air compressor to blow both sides of the switch clear. Don’t just pump antifreeze into the system using your water pump and by-pass kit. Water can remain in the entry valve and (from experience) cause a hairline crack in one or both of elbows coming off the valve. And those particular elbows are hard to find.

16 days ago

NEVER trust what ANY RV salesman or dealership has to say as they don’t know diddly. The only thing they know how to do is to extract as much money from your pockets as possible when you are purchasing a RV, parts for your RV or need to have service done on your RV.

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