Water pressure or pump problem?

[Janb313]

Two campgrounds ago I discovered that my fresh water holding tank was full and I had not put any water in it. The place had strong water pressure and a friend said it was probably backing up into the tank from the pump because of the high water pressure. Next campsite no problem. This campsite has good water pressure and the holding tank is filling again! Do I have a regulator problem or a pump problem? Not sure where to start looking.

[Brian Van Snell]

Jan

You should have a pressure regulator (a small brass device) between the tap at the campsite and the hose to your trailer. Do you have one? It is possible that the water pressure at the campsite is too high.

[Jared J]

I would guess its the pump. The regulator might have failed, but I think the pump should still stop it. Mine holds fine at 90 psi.

[Raz]

If I'm not mistaken there should be a one way check valve between the pump and the faucet. If that valve is not functioning then city water could flow to the tank. I'd try a pressure regulator first and if the tank still fills with lower pressure then check the one way valve. Raz

[rabbit]

Wouldn't the one-way check valve be between the tank and the pump to prevent back flow to the tank?

[Raz]

Originally Posted by rabbit

Wouldn't the one-way check valve be between the tank and the pump to prevent back flow to the tank?

Mine was near the faucet. I figured the placement was to prevent high pressure water from getting to the pump??? Also I think in some cases they are built into the pump.

[Thinh]

...I am not sure about your RV water system but IMO, there should be a check valve(one way) right at Tee connector(city water input/water pump output and input hose/pipe leading to the faucet). If this check valve is defected, city/park water input will go back to your pump and into your tank. I built mine with 2 check valves. Water tank out--->check valve--->water pump--->check valve right before Tee connector. From this intersection, city/park water in-->to the faucet. So there are 2 check valves for city water could get back into the tank. All are tested and work perfectly...Mine has none of regulator.

[Janb313]

I do have a water pressure guage on the hose where it goes into the trailer. I have closed the brass valve (I assume this is the check valve) to keep it from filling up and overflowing which is how I discovered it in the first place. I may try a new regulator first and if that doesn't solve the problem I will be over my head and go for the "experts". Thanks

[Jared J]

Most pumps have the check valve inside them v

[Brian B-P]

In an RV with both city water and tank+pump systems, there are two check valves needed to isolate the two sources from each other:

1. one to keep the pump from pushing tank water backwards into the city (outside) water system - this is usually mounted right at the city inlet, and is not the problem here; and,
2. one to keep city water from pushing backwards through the pump and into the tank - this is usually at or near the pump outlet, and seems to be the problem in this case if it is a normal trailer.

Originally Posted by Janb313

I have closed the brass valve (I assume this is the check valve) to keep it from filling up and overflowing ...

A check valve is not something which you can manually close. It has an internal mechanism which only allows flow in one direction, and no handle or control on the outside.

I agree that this is not likely a regulator problem. Trailers routinely don't need a regulator at all, and the check valve which prevents this problem should not need any help from a regulator.

[Brian B-P]

In my motorhome the same city water hose fitting inlet is used to supply city water for direct use, and to fill the tank; there is no pkace to just pour water into the tank. A diverter valve controls whether the incoming water is directed to the tank, bypassing the pump's check valve.

Although I have not heard of one of our trailers being plumbed in this way, someone certainly could have done this; if so, the valve which was turned to stop the tank from filling might be for that very purpose.