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

wnjj
Explorer II
Mar 03, 2018
RLS7201 wrote:
And in your definition, you defined ONE valve, which is a check valve. In pumps the valves are inlet & outlet valves, not check valves. Some one on the internet misdefined inlet & outlet valves and it caught on. Would you define the valves in an internal combustion engine as check valves?

Richard

You might want to tell the manufacturer of my pump, Flojet, that they shouldn’t be using a “check valve assembly” in their pumps. Described below the exploded view diagram in their publication here: http://www.xylemflowcontrol.com/files/R3426_81000-384.pdf

No, valves in an engine are not check valves because they are operated by mechanical means and therefore could be made to flow either direction by modifying the camshaft. Check valves allow only one way flow by their very design because the movement of fluid or air is what actuates the valve.
RLS7201
Explorer II
Mar 03, 2018
wnjj wrote:
RLS7201 wrote:
So much nonsense about check valves in water pumps. There are NO check valves in water pumps. There are inlet valves and outlet valves. Both an inlet valve and an outlet valve would have to fail for water back flow to the fresh water tank.

Richard

The definition of a check valve: "a valve that closes to prevent backward flow of liquid."

Those inlet and outlet valves you refer to are check valves.

You're right that both the inlet and outlet (check) valves need to fail or get debris in them for water to backflow but it seems to happen often enough as evidenced by the people whose issue goes away by simply using the pump.

And in your definition, you defined ONE valve, which is a check valve. In pumps the valves are inlet & outlet valves, not check valves. Some one on the internet misdefined inlet & outlet valves and it caught on. Would you define the valves in an internal combustion engine as check valves?

Richard
wnjj
Explorer II
Mar 02, 2018
Harvard wrote:
RLS7201 wrote:
So much nonsense about check valves in water pumps. There are NO check valves in water pumps. There are inlet valves and outlet valves. Both an inlet valve and an outlet valve would have to fail for water back flow to the fresh water tank.

Richard

In the water pump that I have disassembled there was only rubber flapper valves (as I recall 3 in PARALLEL). When that pump cycled through the pumping STROKE it pushes water through and opened the flappers. When the pump cycle is not in the pump STROKE cycle the flappers would be closed to prevent back flow. I am not saying all pumps are like my ShureFlow. And yes, in my case, there was grit preventing one of the flappers from closing that allowed back flow when the pump was off.

There's actually the 3 plus one in the center. I assume there are 3 on the inlet side since it's pulling water under a vacuum. The pump stroke pulls water through the 3 then they close as it pushes water back out the center one.

The single valve prevents water from being drawn back into the pump from the pressure side on the vacuum stroke. The other 3 prevent water from pumping back into the tank on the pressure stroke.
wnjj
Explorer II
Mar 02, 2018
RLS7201 wrote:
So much nonsense about check valves in water pumps. There are NO check valves in water pumps. There are inlet valves and outlet valves. Both an inlet valve and an outlet valve would have to fail for water back flow to the fresh water tank.

Richard

The definition of a check valve: "a valve that closes to prevent backward flow of liquid."

Those inlet and outlet valves you refer to are check valves.

You're right that both the inlet and outlet (check) valves need to fail or get debris in them for water to backflow but it seems to happen often enough as evidenced by the people whose issue goes away by simply using the pump.
Harvard
Explorer
Mar 02, 2018
ShurFlo Water Pump Valves

or this....
Harvard
Explorer
Mar 02, 2018
RLS7201 wrote:
So much nonsense about check valves in water pumps. There are NO check valves in water pumps. There are inlet valves and outlet valves. Both an inlet valve and an outlet valve would have to fail for water back flow to the fresh water tank.

Richard

In the water pump that I have disassembled there was only rubber flapper valves (as I recall 3 in PARALLEL). When that pump cycled through the pumping STROKE it pushes water through and opened the flappers. When the pump cycle is not in the pump STROKE cycle the flappers would be closed to prevent back flow. I am not saying all pumps are like my ShureFlow. And yes, in my case, there was grit preventing one of the flappers from closing that allowed back flow when the pump was off.
RLS7201
Explorer II
Mar 02, 2018
So much nonsense about check valves in water pumps. There are NO check valves in water pumps. There are inlet valves and outlet valves. Both an inlet valve and an outlet valve would have to fail for water back flow to the fresh water tank.

Richard
Dutch_12078
Explorer II
Mar 02, 2018
The check valve in the pump is the issue, and if disassembly and cleaning it doesn't fix it, then the quick low cost fix is to add an external check valve on the output side of the pump. Most hardware and home improvement stores will have one that will work.
Monello
Explorer
Mar 02, 2018
MrWizard wrote:
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 ?

I should not have referred to them as holding tanks. It's the fresh water tank that you would fill if you were going to be dry camping. I do have a pressure regulator attached to the hose. It's not 1 that has a gauge.
Farmboy666
Explorer
Mar 01, 2018
MrWizard wrote:
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 ?

I take it that he is calling the fresh water tank the holding tank since heading says water holding tank