Fresh Water Tank Overflowing

[jimm7007]

2019 Forest River Surveyor 241RBLE. After attaching the campground water line with our filter and 40-50 PSI pressure reducer, we have experienced two nights of the fresh water tank (we normally do not use) overflowing out the filler port for fresh water tank on the camper side wall. In-line valves at back of water heater and adjacent to fresh water on board pump ( pump not "on" when this happened) are in normal positions after de-winterizing the camper. We took normal showers and washed dishes as we have always done.
We repeated the above install on arrival home and even installed a new 40-50 PSI pressure reducer in the hose inlet line. Overflow still occurred from the fresh water tank.
What is causing this overflow?
Jim M.

[HONDAMAN174]

Turn off the city water supply and turn on the water pump and open a faucet. Run tgat for 2 minutes.

In fact just run off your fresh tank until empty so you are not wasting that wTer.

[jimm7007]

Thanks, Hondaman174. I did as you recommended and am still getting overflow into the fresh water tank when city water turned on. I have left the fresh water tank drain open so
the chance of overflow is minimized.

[Rhumblefish]

Check valves are always the first place to check. Flipping back and forth between city pressure and pump pressure should exercise sticky valves. could be getting flow through the pump, as well, but the downstream check valve should be catching this.

Lesser known, but one we just saw: Check that your showermiser (if so equipped) is turned OFF (eg, pointed at showerhead, not freshwater return), and that your shower (indoor and out, if you have one), are both turned off by the handles/knobs, and not simply the control at the end of the showerwand

[NavyLCDR]

There are two main causes for freshwater tank filling on city water:

1. Valve out of position. Do you have a shower miser system? It diverts water going to the shower into the freshwater tank until hot water arrives at the shower to minimize waste. If the shower miser is left in the wrong position, it fills the freshwater tank from city water.

2. Faulty check valve in the water pump. RV water pumps have internal check valves that keep the pressurized side of the from flowing backwards through the pump to the freshwater tank. Usually problems with the check valves are caused by debris stuck in them, and running water through the pump by opening a closing a faucet several times with the water pump running (no city water) will clear it. However the check valve may have failed completely.

You can check for water pump check valve problem by removing the cap from the strainer at the inlet to the water pump while you have city water connected. If there is no leak, the water in the strainer should drain back into the freshwater tank and the strainer should remain empty. If you can see water trickling from the inlet of the water pump back into the strainer, then you have a bad pump check valve.

If you have a bad water pump check valve you have a couple of options:
1. Replace the water pump.
2. Buy a rebuild kit (diaphragm) and rebuild the water pump.
3. Install an external check valve, which should go on the inlet side of the water pump.

[Alde]

Had the same thing happen, removed pump, found plastic from tank install stuck in check valve,cleaned out pump and strainer,yes it got past strainer, reinstalled and added additional check valve before pump, that was 2 years ago, new check valve had clear strainer that I can check whenever, cheaper than new pump

[Custmachr]

Originally Posted by NavyLCDR

There are two main causes for freshwater tank filling on city water:

1. Valve out of position. Do you have a shower miser system? It diverts water going to the shower into the freshwater tank until hot water arrives at the shower to minimize waste. If the shower miser is left in the wrong position, it fills the freshwater tank from city water.

2. Faulty check valve in the water pump. RV water pumps have internal check valves that keep the pressurized side of the from flowing backwards through the pump to the freshwater tank. Usually problems with the check valves are caused by debris stuck in them, and running water through the pump by opening a closing a faucet several times with the water pump running (no city water) will clear it. However the check valve may have failed completely.

You can check for water pump check valve problem by removing the cap from the strainer at the inlet to the water pump while you have city water connected. If there is no leak, the water in the strainer should drain back into the freshwater tank and the strainer should remain empty. If you can see water trickling from the inlet of the water pump back into the strainer, then you have a bad pump check valve.

If you have a bad water pump check valve you have a couple of options:
1. Replace the water pump.
2. Buy a rebuild kit (diaphragm) and rebuild the water pump.
3. Install an external check valve, which should go on the inlet side of the water pump.

Also if you have the Anderson selector valve the o-ring in the valve could be bad.

[5picker]

And... if you have a Showermiser valve in the shower, it can fill the fresh tank.

This issue and question gets asked on a weekly basis and there are hundreds of posts about the fresh tank filling on city water.

One thing you can do to prevent the fresh tank filling if the pump's internal check valve is leaking (bypassing internally)... if you have a winterization valve near the pump that you use to pull antifreeze into the system... turn the winterization bypass valve to the winterization mode and then cap off the antifreeze line with a hose cap or if you have a port on the side of the R/V, screw in a $1 inline hose shut off and shut it off. The water bypassing the pump will be diverted to the winterization port and can be capped off and it won't fill the tank.

[jimm7007]

Thanks again to all of you. Am going to do some more checking on existing pump before installing new pump on order.

[jimm7007]

Alde: What is brand and model of new check valve you installed before pump?

[jimmoore13]

One way to quickly test the water pump check valve is to:

• Turn off city water;
• Bleed off city water pressure...open a faucet until the pressure is relieved;
• Turn on the water pump;
• The water pump should bring up the pressure by drawing water from the fresh tank;
• IF THE PUMP CYCLES ENDLESSLY, there's your sign. The water pump brings up the pressure, but the check valve leaks pressure back into the fresh tank, so the pump runs again.

That's a pretty reliable test of the check valve. Pump cycling may happen from once every 5 minutes to once every 30 seconds...depending on how badly the check valve has failed. Given that your fresh tank fills in 24 hours or so, a bad check valve would be leaking back a LOT of water.

If you have no pump cycling using the water pump, look elsewhere for the problem. Others pointed out the showermiser as a likely culprit. As for the outdoor shower, that's unlikely. It might cause tepid hot water, but neither the indoor nor outdoor showers will flow back into the fresh tank. Only the showermiser will do that. But, by all means, be sure to shut off showers at the valves...not just the showerhead.

One more thought on the showermiser. One would expect it to bypass water back to the fresh tank ONLY WHEN USING THE SHOWER. If the shower valves are closed, there should be no water feeding back into the fresh tank. And you'd have a horrible shower. That bypass (showermiser) is downstream of the main shower valves and should not pass water unless the shower valves are open...otherwise it would be cycling water constantly. To make that happen, the showermiser would have to be set to divert water to the fresh tank, the shower head would need to be shut off, and the shower hot water faucet would very likely be on. And that means your hot water heater would be working overtime to keep up...and you'd hear water running constantly. That's a lot of things that must line up just right for that to be the reason.
So that brings us back to the check valve.

Note that manually operating the pump a few times may clear out any loose junk that is preventing a good seal on the check valve, but in many cases, no amount of fiddle farting around with the pump will clear the valve. Things like calcium deposits are the likely culprit, and they seldom just wash away.

While you might attempt a repair to or cleaning the check valve, a decent pump is under $100. And replacement is super easy. I would not put much time into trying to fix a check valve unless I could use something like CLR on it easily.

ONE MORE NOTE: If your showermiser is the culprit, you will probably have poor water pressure throughout the rig. If the check valve is the culprit, the leak back is not enough to compromise water pressure.

That's enough guesswork from me.

[jimm7007]

Thanks. I installed a new Shurflo 4008-101-E65 pump today. It seems to have solved the problem. Am wondering if adding an additional brass check valve from Camco or similar would aid in preventing issue in the future.

[Larry-NC]

Originally Posted by jimm7007

Thanks. I installed a new Shurflo 4008-101-E65 pump today. It seems to have solved the problem. Am wondering if adding an additional brass check valve from Camco or similar would aid in preventing issue in the future.

Why not wait until you need it? It might be years.

[jimmoore13]

Originally Posted by jimm7007

Thanks. I installed a new Shurflo 4008-101-E65 pump today. It seems to have solved the problem. Am wondering if adding an additional brass check valve from Camco or similar would aid in preventing issue in the future.

If there's room, you might install a 1/4-turn ball valve in the line between the fresh tank and the pump. Given that you tend to use sites with hookups, this would be a great belt and suspenders approach to the issue. But if you dry camp very often, forgetting the ball valve and running the pump dry won't be good for the pump.

So, adjust your tactics to your camping style.

[SEB]

Originally Posted by 5picker

And... if you have a Showermiser valve in the shower, it can fill the fresh tank.

This issue and question gets asked on a weekly basis and there are hundreds of posts about the fresh tank filling on city water.

One thing you can do to prevent the fresh tank filling if the pump's internal check valve is leaking (bypassing internally)... if you have a winterization valve near the pump that you use to pull antifreeze into the system... turn the winterization bypass valve to the winterization mode and then cap off the antifreeze line with a hose cap or if you have a port on the side of the R/V, screw in a $1 inline hose shut off and shut it off. The water bypassing the pump will be diverted to the winterization port and can be capped off and it won't fill the tank.

This! I had same happen while on site and for quick fix turned off winterization valve to fresh tank. That stopped it. Cleaned the pump/valve when I had time and that fixed it too. I just leave the winter valve closed all the time unless I plan on using the tank/pump. Never any more issues.

[rowdy boys 3]

I added an external check valve to the water pump, to stop city water connection from filling the fresh water tank and overflowing.

[pitzhauler]

You don't need to fill fresh water tank when on city water . Only need to fill fresh tank if NO water is avalible at camp site

[Reverse_snowbird]

Originally Posted by pitzhauler

You don't need to fill fresh water tank when on city water . Only need to fill fresh tank if NO water is avalible at camp site

They are not intentionally filling the fresh water tank. There's a valve that occassionally will fail and fill the fresh water tank while you're on city water. The only way you find out that has happened is by seeing water flowing from the overflow vent under the rig.
It's most annoying, but following the instructions to turn off city water, open the faucets, running the water pump, etc. usually will solve the problem. Other solutions (above) can solve the problem permanently.

[01tundra]

If you can't get the pump's internal check valve to stop leaking by, one option is to screw an external check valve onto the inlet (suction) side of the pump.

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