I have a class A Coachmen Aurora 2007 that I use for full time living. Recently while hooked up to city water and all the knobs on the panel show city water, my holding tank is filling up. It fills to the point where it overflows and spills out.I have never had this issue before. We are several months into our Florida adventure. I don't have any schematics of the water system. It appears that somehow while under pressure, water is flowing into the holding tanks. Those tanks should be empty.Right now we are running off of the water pump using the tank water. Every few day I'll fill the tanks so we don't run out. I'd like to figure out how to fix this but for the life of me I don't know where to start.We are scheduled to house sit at the end of the summer. If I don't get this worked out by them I'll drop it at the shop for them to remedy. Unless someone out there in the internet world has faced this challenge before.So let's fix this together and I'll let you know how it turns out.In my 11 years of RVing I've discovered 2 things that fix most problems. Time & money. Just how much of each is always variable. Some fixes are easier than others. I'm hoping this is 1 of those.TIA

Hanging on city water is dangerous IMO. Fill your fresh water tank and use it. Then refill as necessary.

My new-to-me travel trailer just did that. There is a checkvalve in the waterpump which is supposed to work... mine failed. Installed a cut-off valve on the waterline coming in (bandaid solution.) Solved the problem. The fresh water tank swelled so bad, the pump actually made a dent in it. Upside is I can lift the bed, turn the valve and the freshwater tank fills while the water is connected to the city water inlet. Downside is, the water pump does not work correctly (on/off/on/off) while trying to use pump only. Can only have it turned on while using the tank, then make sure it is turned off.Not a bad idea to have the cutoff valve, but I do have to spring for a new waterpump down the line.

Yep. Water pump shouldn’t allow backflow, but is. The fix can be as cheap as taking it apart to clean it or even just using the pump. Worst case is a new pump.Others with the same issue. Both cleared up by using the pump:https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29566376https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29569488I assume you are referring to the fresh water tank. Holding tanks are typically the gray/black waste.

In one of my rigs I could only fill with a water hose connected by screw fittings. There was no hose trough to just put the hose into. If yours is like that, there is a valve that you have to shut off that allows outside water to go to the taps and not to the tank. If water still goes to the tank while connected, there is a check valve in the actual pump (you can't see it) that should prevent it.Personally, I like to fill my tanks and run with the pump until it needs filling again. I do not like the constant pressure on the rigs pipes when I am away from it or when we are sleeping. Too many people have come home to burst pipes, just fill, use the pump when you need it, and shut off the pressure when you don't.

bypas or no bypassthe water should not being going pass the toilet valve or water tapswhat is filling up the black tank, or both black and greythe toilet valve is weak and/or you have way to much water pressuredo you have a water pressure regulator on the shore hose/fill ?you should have one when connected to city watercheck valve in the water pump stops back fill to the fresh water tankit has nothing to do with the 'holding tanks'so what are you saying, what is happening ?

Water holding tank is filling while on city water

allenm
Explorer
Mar 01, 2018
I can confirm that water pressure too high in campground can cause a good check valve in water pump to leak water into the fresh water tank, as well as cause toilet to leak water into black water tank. Solution - install a good water pressure regulator, the kind with a gauge. In my case, the campground pressure was running around 100 lbs, but only sometimes.
MrWizard
Moderator
Mar 01, 2018
bypas or no bypass
the water should not being going pass the toilet valve or water taps

what is filling up the black tank, or both black and grey

the toilet valve is weak and/or you have way to much water pressure

do you have a water pressure regulator on the shore hose/fill ?

you should have one when connected to city water

check valve in the water pump stops back fill to the fresh water tank

it has nothing to do with the 'holding tanks'

so what are you saying, what is happening ?
Artum_Snowbird
Explorer
Mar 01, 2018
In one of my rigs I could only fill with a water hose connected by screw fittings. There was no hose trough to just put the hose into. If yours is like that, there is a valve that you have to shut off that allows outside water to go to the taps and not to the tank.

If water still goes to the tank while connected, there is a check valve in the actual pump (you can't see it) that should prevent it.

Personally, I like to fill my tanks and run with the pump until it needs filling again. I do not like the constant pressure on the rigs pipes when I am away from it or when we are sleeping. Too many people have come home to burst pipes, just fill, use the pump when you need it, and shut off the pressure when you don't.
wnjj
Explorer II
Mar 01, 2018
Yep. Water pump shouldn’t allow backflow, but is. The fix can be as cheap as taking it apart to clean it or even just using the pump. Worst case is a new pump.

Others with the same issue. Both cleared up by using the pump:

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29566376
https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29569488

I assume you are referring to the fresh water tank. Holding tanks are typically the gray/black waste.
LadyRVer
Explorer II
Mar 01, 2018
My new-to-me travel trailer just did that. There is a checkvalve in the waterpump which is supposed to work... mine failed. Installed a cut-off valve on the waterline coming in (bandaid solution.) Solved the problem. The fresh water tank swelled so bad, the pump actually made a dent in it.

Upside is I can lift the bed, turn the valve and the freshwater tank fills while the water is connected to the city water inlet. Downside is, the water pump does not work correctly (on/off/on/off) while trying to use pump only. Can only have it turned on while using the tank, then make sure it is turned off.

Not a bad idea to have the cutoff valve, but I do have to spring for a new waterpump down the line.
Lwiddis
Explorer II
Mar 01, 2018
Hanging on city water is dangerous IMO. Fill your fresh water tank and use it. Then refill as necessary.

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Water holding tank is filling while on city water

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