Fresh water tank filling on city water

Jason.rhodes86 · 07-01-2022, 02:24 PM

Forgot I had my drain open from last weekend from using water pump. Hooked up to city water today and noticed it started draining. After a while my gage is showing water tank is filling. What Would cause this and what’s the solution?

**chuckster57** · 07-02-2022, 04:42 AM

Do you have a valve at the connection for tank fill/city water? Was it set correctly?

Jason.rhodes86 · 07-02-2022, 05:21 AM

There are separate hookups for each. I connected to the city water, and it works fine into the camper, but it is also filling the fresh water tank, which has a separate connection.

**chuckster57** · 07-02-2022, 05:58 AM

If the tank fill is a separate connection then the check valve in the water pump is the issue. You might try turning off the city water and operating the water pump for a few minutes. If that doesn’t fix it then you’ll need to rebuild/replace the pump.

Jason.rhodes86 · 07-02-2022, 06:02 AM

Yeah tried using the water pump for a while then switching back and didn’t fix it. So looks like a pump issue. Frustrating because thing is only a year old. Thank you

Poppy · 07-02-2022, 01:56 PM

Jason, my trailer is only three years old, I’ve never used the fresh water tank or the pump, and last week we had to empty the tank twice. Seems like last week was not a good time to camp. YEAH, RIGHT!
I think I had a repair to do about every day, and now that we’re home, I still have two more to do.
I still enjoy camping. Someone wii have to pry the keys from my cold dead fingers before I give it up.

Jason.rhodes86 · 07-03-2022, 04:19 PM

Quote:

Originally Posted by chuckster57

If the tank fill is a separate connection then the check valve in the water pump is the issue. You might try turning off the city water and operating the water pump for a few minutes. If that doesn’t fix it then you’ll need to rebuild/replace the pump.

The check valve is inside of the water pump correct?

**JRTJH** · 07-03-2022, 05:00 PM

Quote:

Originally Posted by Jason.rhodes86

The check valve is inside of the water pump correct?

Yes. It's a part of the pump diaphragm assembly. You can usually disassemble the pump head and find some plastic drill shards that were drawn into the pump from the fresh water tank. Those plastic shards are a "product of building the tank" and come from drilling the mount holes in the tank. You'd be amazed at the amount of "trash" that's in the FW tank in most RV's....

Do yourself a "favor" and when you clean out the pump head, also install a inflow strainer basket on the pump inlet fitting. It'll be one of the best $8 investments in plumbing protection you could make.

Here's a photo of the strainer basket and the pump head diaphragm check valve.

BillBachman · 07-04-2022, 10:31 AM

Without seeing the pump, does the pump itself have to outlets? One going to the sinks and one going to the city water side? Because it is pressuring up and coming out the city water inlet.

bobbecky · 07-04-2022, 10:58 AM

If the internal check valve is leaking and the pump otherwise works fine, adding an inline check valve on the pressure side of the pump will solve the problem. I did this years ago and it worked perfectly. I had to replace the pump some years later but the check valve is still in place and does not restrict water flow. It is the brass fitting near the lower center of the photo and is a Sharkbite type fitting.

**JRTJH** · 07-04-2022, 11:22 AM

Quote:

Originally Posted by bobbecky

If the internal check valve is leaking and the pump otherwise works fine, adding an inline check valve on the pressure side of the pump will solve the problem. I did this years ago and it worked perfectly. I had to replace the pump some years later but the check valve is still in place and does not restrict water flow. It is the brass fitting near the lower center of the photo and is a Sharkbite type fitting.

That will work to resolve the backflow problem into the tank, but does nothing to remove the foreign object/drill shard/trash from the pump diaphragm. Eventually, that piece of "what ever it is" will wear into the diaphragm and affect its ability to maintain the seal required to pressurize the water drawn into the pump. When that happens, that "piece of stuff" will have damaged the pump diaphragm, likely beyond repair. Even with the addition of another check valve in the pump output tubing, I'd recommend getting the trash out of the pump head before it causes irrepairable damage to the pump.

Jason.rhodes86 · 07-04-2022, 02:20 PM

Quote:

Originally Posted by BillBachman

Without seeing the pump, does the pump itself have to outlets? One going to the sinks and one going to the city water side? Because it is pressuring up and coming out the city water inlet.

One outlet. The pump draws from the tank and pumps out into mainline. The city water intake goes into that same line but after where it comes out of the pump if that makes sense

BillBachman · 07-04-2022, 05:49 PM

So thinking the whole time to my self after back flushing the tank to pump line. Blowing the line from the pump to the faucet out and tearing the pump apart put it all back together and still did the same thing. The whole time thinking this should have a check valve keeping it from going out the tee to the city water inlet. Well that is exactly what it has right behind the inlet screen on the outside of the trailer. I had my wife plug the hole to see just how much pressure I got at the faucet and she stuck her finger in there after she pulled the screen out and it reseated the little check valve at the inlet. Bam! It worked. Thanks for all your help everyone. Hope this saves someone else a little leg work. I believe someone might have put the screen in backwards which kept the check valve from closing.

Jason.rhodes86 · 07-04-2022, 05:54 PM

Quote:

Originally Posted by BillBachman

So thinking the whole time to my self after back flushing the tank to pump line. Blowing the line from the pump to the faucet out and tearing the pump apart put it all back together and still did the same thing. The whole time thinking this should have a check valve keeping it from going out the tee to the city water inlet. Well that is exactly what it has right behind the inlet screen on the outside of the trailer. I had my wife plug the hole to see just how much pressure I got at the faucet and she stuck her finger in there after she pulled the screen out and it reseated the little check valve at the inlet. Bam! It worked. Thanks for all your help everyone. Hope this saves someone else a little leg work. I believe someone might have put the screen in backwards which kept the check valve from closing.

So where exactly was this screen and valve? Not in the pump but somewhere by where the water goes into the trailer?

**JRTJH** · 07-04-2022, 06:04 PM

Quote:

Originally Posted by Jason.rhodes86

So where exactly was this screen and valve? Not in the pump but somewhere by where the water goes into the trailer?

It's where the water hose screws into the trailer sidewall (or convenience center). There is a hose washer with a screen in it. Behind that screen is a one way valve that allows water into the trailer and, if you aren't connected to city water, prevents the pump from pushing water out of that connection. "One way in, stops water going out"....

Be careful "poking around in the connection". If you dislodge the inlet valve, you may not be able to get it reseated.

BillBachman · 07-04-2022, 06:09 PM

Yes. Right behind the threaded inlet that you hook your hose to where there is a screen to keep foreign objects from entering like on a washing machine hose.

BillBachman · 07-04-2022, 06:11 PM

Yep! That’s the one!

**JRTJH** · 07-04-2022, 06:13 PM

Quote:

Originally Posted by BillBachman

Yes. Right behind the threaded inlet that you hook your hose to where there is a screen to keep foreign objects from entering like on a washing machine hose.

That valve does not prevent backflow through the pump that can fill the fresh water tank, which is the OP's issue. The valve you discovered prevents "pump pressure from squirting out the side of the trailer when using the onboard water system".... They are two different valve systems, located in two different places (one in the city water inlet connection, the other in the water pump head) and they accomplish two different functions.....

Jason.rhodes86 · 07-04-2022, 06:32 PM

Quote:

Originally Posted by JRTJH

That valve does not prevent backflow through the pump that can fill the fresh water tank, which is the OP's issue. The valve you discovered prevents "pump pressure from squirting out the side of the trailer when using the onboard water system".... They are two different valve systems, located in two different places (one in the city water inlet connection, the other in the water pump head) and they accomplish two different functions.....

Yeah my issue is with water going back thru the pump and into the tank, so probably not anything to do with a screen on the intake. Thank you though

**JRTJH** · 07-04-2022, 06:52 PM

Quote:

Originally Posted by Jason.rhodes86

Yeah my issue is with water going back thru the pump and into the tank, so probably not anything to do with a screen on the intake. Thank you though

Your "backflow into the fresh water tank and the fixes for that issue" are explained in posts #8 and #10. It's the pump head and the internal backflow valve that's the problem. Until you get the pump head to stop leaking into the tank, your fresh water tank will continue to be "filled and spill onto the ground.

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