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oldtrucksrul 03-08-2014 04:42 PM

City Water is Overflowing holding tank???
I have a 2009 Classic 27fb, I hooked it up to city water and water started running out of the holding tank fill. I also noticed when everything is turned off the pump continues to run. What's going on?? Thanks!!

n2916s 03-08-2014 04:51 PM

This is a puzzle. If you are on city water, the pump shouldn't even be switched on much less running with all the fixtures closed.

There is a check valve to keep the city water from filling the fresh water tank. On mine the valve is part of the pump. If that has failed, the fresh water tank will fill and overflow out the vent. How water is getting into your holding tank is a mystery to me...

I would shut off the city water and only switch on your fresh water pump when you need it. Commence troubleshooting when able.


Protagonist 03-08-2014 05:02 PM

Troubleshooting tip:
If you have a full freshwater tank (which you're incorrectly calling a "holding tank"?) then disconnect the municipal water and turn on the pump.

If the check valve in the pump is defective, then the pump will provide water just fine when you open any faucet or flush the toilet. However, it will not hold pressure, because as soon as the pump shuts off, water rill run backwards through the inactive pump and back into the freshwater tank. This will cause the pump to start up again to build up pressure, and it will be an endless on/off/on/off cycle. In other words, it will act as if there's a leak (there is, through the check valve) but you won't be able to spot a leak anywhere because it's all internal.

n2916s's advice to only turn on the pump when you need water is sound, until you can get the problem fixed. BUTů I'd go a step farther, and tell you to only turn on the water heater when you need it, too. If the freshwater plumbing is draining itself back into your freshwater tank, your water heater might not stay full, either. I found out a week ago that when my water heater is only partially full, the thermostat will not turn it off, and it will boil water in the tank. Which is not good for the heater, and can injure you if you open a hot water tap and get scalded.

oldtrucksrul 03-08-2014 05:21 PM

Thanks!! I did miss-speak on the holding tank verbiage, I was typing in a panic trying to get an answer. The check valve does sound like the culprit. I will do as you said and also turn the water heater off tonight. Thanks!!!

Splitrock 03-08-2014 06:00 PM

Water valve before electric pump
I may have installed a valve between the fresh water tank and the electric water pump and another valve to isolate the city water supply pipe. My pump check valve works but it will fail sometime in the future and I just might hate drama.

ticki2 03-08-2014 06:38 PM


Originally Posted by Splitrock (Post 1425237)
I may have installed a valve between the fresh water tank and the electric water pump and another valve to isolate the city water supply pipe. My pump check valve works but it will fail sometime in the future and I just might hate drama.

I did the same with the added valve . I found the the pump worked fine and the pump check valve was adequate for holding prime to the fresh water tank but not strong enough to hold pressure against the city water .

Al and Missy 03-08-2014 07:42 PM

Pressure Regulator?
My 2001 Safari 25 has a pressure regulator on the city water input to protect the trailer plumbing from over pressure. Yours may be defective or misadjusted. I'd suggest measuring the pressure at a faucet to be sure.


SteveH 03-08-2014 08:53 PM

Basically, the water pump is several diaphragms with each having it's own check valve, and if any foreign matter lodges under any of the check valves, water will flow backwards thru the pump into the water tank.

Like others, I would suggest turning off the city water supply and just use the tank water and pump. Odds are, whatever is lodged under the pump check valve will be moved out, and the pump will again not flow water in reverse.

If this doesn't work after a while, you will either have to replace the pump, or remove, disassemble, clean, and reassemble to get it to work properly again. Additionally, I would suggest in the future you use a water filter in your hose both when you fill the tank and when connected to city water.

idroba 03-08-2014 11:18 PM

On a friends Airstream, with a new replacement pump, we found it was constantly turning on and off, on and off. No water leaks anywhere. I pulled the pump and took it apart and found a tiny curl of white poly from the water tank under one of the three pumping chamber valves. The curl had even made it through the filter which was in place. It caused a back leak so the pressure would be built up, then leak back into the tank, then run again and on and on. Had he had city water, the leak would have eventually filled his water tank.

Bbelk 03-29-2014 11:38 AM

Same Issue on a 2010 27FB
I just found I have the same issue. We had noticed our pump cycling in the night a couple times and I couldn't find a leak anywhere. Now I know the first 59 gallons won't show up anywhere. The leak is somewhere between a drip and a dribble, so for today, I have just opened the drain valve on the freshwater tank so the drip will move under the trailer rather than down the side. I will try a few easy things, like living off the pump on the next trip to see if it will clear up.

We are about a month away from a 4 month trip, but I suppose changing the pump is only slightly more traumatic on the road than it would be here. I am going to hope for the miracle self cure.

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