FW tank overfilling with city water connected?

[mdtravelers]

last weekend I filled the freshwater (FW) tank before arriving at the campground. Once there I found out we had a freshwater hook-up at the site. the next morning I noticed the FW tank had water dripping out of the overfill hole next to the fill hole. I drained a few gallons from the FW tank and the drip stopped. later that day I noticed the drip had started again. It appears that with the city water hooked up there is some amount of water entering the FW tank. can anyone shed some light on what might be happening?

Thanks, Dave

[kscherzi]

The trailer water pump has a one way check valve to prevent pressured water from flowing back into the water tank. The city water inlet connects downstream from the trailer water pump, and uses the pumps check valve in the same manner.

Its possible there's some gunk in the pump holding the check valve slightly open. Though a pain it is possible to disconnect parts of the pump to clean it out.

A way to confirm this may be the problem is to disconnect city water and use the pump to pressurize the system. If the check valve is leaking the trailer automatic water pump will periodically "burp" (run a second or two) to re-establish pressure.

[OTRA15]

Lots of advice in many threads/posts:

"pump check valve bad tank filling" -- https://www.google.com/search?q=pump...=airforums.com

First step is to turn the pump on and off repeatedly, sometimes with city water also on, sometimes not, and hope that grit in the check valve will be dislodged. Always use an inline RV water filter in the hose, both for city water and for filling the tank. Always.

Good luck,

[RAH]

You probably have an internal leak in the water pump.
If you replace the water pump with a new one, that will in all likelihood solve the problem.
There are some nice VSD (variable speed demand) water pumps out there that are quiet.
Best of luck.

[VeloBuckeye]

Related story I think - last week we camped with friends who are new to camping and have a nice new SOB. He had this same issue - water flowing out of his FW tank while hooked to and using city water with a filter. We tried all the things in this post which didn’t help. He ended up calling his dealer who asked a simple question about their shower head handle cut-off switch — was the shower faucet turned on and the flow stop on the handle shut off as well? Well his wife had taken a shower earlier and left the faucet on and she shut of the flow at the shower head as she exited the shower (she didn’t know to shut of the main faucet on the shower wall). Once my friend shut off the wall valve and opened up the shower head stop, all was resolved and things returned to normal operation.

I understand the issue and role of the pump check valve but I don’t understand how this caused the FW tank to fill and overflow?

Any thoughts?

[CBWELL]

That makes absolutley no sense at all!!I see no way that a shower valve being in one position or another has any effect on the water pump check valve letting water backflow into the fresh water tank.

[VeloBuckeye]

Originally Posted by CBWELL

That makes absolutley no sense at all!!I see no way that a shower valve being in one position or another has any effect on the water pump check valve letting water backflow into the fresh water tank.

Yeah, that was my thought as well - but it worked...

[Mx468]

Add one of these on output side of waterpump and problem should be solved. Backflow preventer.
https://www.amazon.com/Camco-23303-B...00231742&psc=1

[Sparkle]

Same thing happened to me on my 2018 Bambi. I tried tricking it into unsticking the check valve. It didn't work, got a new water pump installed.

[GatorDave]

Also would suggest a water pressure regulator at the campsite water hook up. I have encountered water pressure at 80psi which can overload the internal valves

[guskmg]

I just finished modifying my fresh water system to do that: Fill the fresh water tank with city water to eliminate having to disconnect city water and manually fill the tank. So, two "Tees", 4 female threaded fittings, two 9" PEX pipes, 4 cinch clamps, 2 90 threaded elbows. an electric motor driven valve, a pilot lighted switch, and some wires, it's done. What you are doing is by-passing the pump. Just remember to remove the water fill cover before pressurizing the fresh water tank. Direct city water fills the tank fast.
guskmg

[suncoasteng]

Why do any RV'ers hook up to city water???? You have a fresh water tank and a 12V pump. Use it for their purpose. Filling and draining the tank ensures you have constant turn over in your tank. And the 12V pressure pump will probably last longer than your TV. When you connect to city water, you risk over pressure that can bust a water line and flood your unit while you are out for the day. Plus you fail to learn how to conserve water and reduce your daily consumption.

[rmkrum]

In our case, DW takes very long, very hot showers. Hates pump noise. Will not do Navy Showers unless we’re very low on water or disconnected. On hookups I dump gray water continuously and the water heater is tankless.

She enjoys her hot shower, I enjoy the peace and quiet, and then all is right with the world. We’ve been married 49 years so I guess her continued ability to take long hot showers on the road or at home is a good thing.

[SlvrTwinkie]

Originally Posted by Mx468

Add one of these on output side of water pump and problem should be solved. Backflow preventer.
https://www.amazon.com/Camco-23303-B...00231742&psc=1

With all the pump replacements the factory has to pay for on new trailers, I can not figure out why they just do not install one of these at the factory to start with. This would save them so much $$ do to faulty pump check valves. When I install our accumulator I will be installing one of these to prevent pump check valve issues. I already need to either clean or replace the one on the city side just before the factory regulator, I get a slight drip from city hook up when using the FW pump.

[Union Hill]

I have an 1989 29' Excella and am working with it to learn the operations and to make repairs. I filled the fresh water tank yesterday and was surprised to find that when I opened the plastic screw on cap to the inlet there was no threaded fitting to attach the hose to. Instead, there was a piece of black tubing (14" long) with a fitting on the end that attached to the city water supply hose.

I inserted that black stub hose into the opening and filled the tank, which soon overflowed through the white and green tubing between the inlet fitting and the top of the water tank. The tubing appears to be about a 1-1/4" ID.

1. I was under impression that a city water hose could be attached to the fill device and left turned on until the trailer is moved. That is not possible with the setup I have because the supply hose simply slips inside the green/white tubing to the tank top, and there is no means to stop the water flow once the tank is full.

2. Am I incorrect in thinking the 1989 AS units did not have city water connections that allowed the city water supply hose to be left in place (that they only allowed hose filling until the tank is full, and you then take away the city supply hose until the tank needs refilling manually).

3. My guess is that the previous owner ran into an issue with the hose fitting and rather than find a replacement he simply created the supply tube described above to allow refilling, albeit manually each time. If there originally was a fitting that allowed the supply hose to be left in place, are there any suggestions about sourcing one or a replacement fitting today?

This Air Forums is an absolute gold mine of information and suggestions, and many thanks in advance for any input you may have on this matter.

Regards, Lorne

[Ultraclassic]

Lol

Originally Posted by rmkrum

In our case, DW takes very long, very hot showers. Hates pump noise. Will not do Navy Showers unless we’re very low on water or disconnected. On hookups I dump gray water continuously and the water heater is tankless.

She enjoys her hot shower, I enjoy the peace and quiet, and then all is right with the world. We’ve been married 49 years so I guess her continued ability to take long hot showers on the road or at home is a good thing.

[Ultraclassic]

Originally Posted by Union Hill

I have an 1989 29' Excella and am working with it to learn the operations and to make repairs. I filled the fresh water tank yesterday and was surprised to find that when I opened the plastic screw on cap to the inlet there was no threaded fitting to attach the hose to. Instead, there was a piece of black tubing (14" long) with a fitting on the end that attached to the city water supply hose.

I inserted that black stub hose into the opening and filled the tank, which soon overflowed through the white and green tubing between the inlet fitting and the top of the water tank. The tubing appears to be about a 1-1/4" ID.

1. I was under impression that a city water hose could be attached to the fill device and left turned on until the trailer is moved. That is not possible with the setup I have because the supply hose simply slips inside the green/white tubing to the tank top, and there is no means to stop the water flow once the tank is full.

2. Am I incorrect in thinking the 1989 AS units did not have city water connections that allowed the city water supply hose to be left in place (that they only allowed hose filling until the tank is full, and you then take away the city supply hose until the tank needs refilling manually).

3. My guess is that the previous owner ran into an issue with the hose fitting and rather than find a replacement he simply created the supply tube described above to allow refilling, albeit manually each time. If there originally was a fitting that allowed the supply hose to be left in place, are there any suggestions about sourcing one or a replacement fitting today?

This Air Forums is an absolute gold mine of information and suggestions, and many thanks in advance for any input you may have on this matter.

Regards, Lorne

The Airstream has a fresh water fill port, this fills the fresh tank only. The city hook up by passed the fresh tank and goes directly to your taps. If you turn on the pump you would get a mix of both.

If your fw tank is over filling then there is a internal leak, most likely at the "built in 1 way check valve " on the pump. Or a extra check valve installed same issue.

[n2916s]

Your freshwater hookup is on the left rear of your trailer near the left side of the bumper. This is where you would hook up to city water.

The fill port for the fresh water tank you have already found.