FTC Disclosure: I get commissions for purchases made through some of the links in this article For more information, visit our Advertising Disclosure Page.

How Do I Stop The City Water From Filling The Fresh Water Tank On My 5th Wheel Trailer?

by Lynette Brennan
(Oregon City, OR, USA)

When I hook up to city water in my 1993 Nomad Fifth Wheel it eventually fills my fresh water holding tank. I thought that the two were separate.

I leave the city water on till I know it has enough water to use pump and then turn the city water off. I looked for some kind of valve I could switch but didn't see one.

I would appreciate any info you can give me. There are separate compartments for the city water and the water tank fill. The rig is new to us and I noticed the problem when we went camping for a week and there was water running out the fill compartment. We have never filled the water tank. I even drained the fresh water tank to see if it would fill again and it did.

Thanks for any help.

ANSWER: Greetings Lynette thanks for submitting your question on our Ask An RV Question Page.

I am a bit confused on what is going on with your 5th wheel Trailer. The fresh water system on your 5th Wheel RV should fit in one of the two categories below.

1. You only have one fresh water connection. In the compartment where you connect the Fresh Water Hose is a valve or lever which is marked with 2 positions. The Valve or lever has a tank fill position and a city water position. When the valve is set to city water position no water should be entering your fresh water holding tank.

2. Your 5th Wheel could have two separate Fresh Water Hose connections; one should be marked as "Tank Fill" and the other one should be marked as "City Water". When you are hooked up to the City Water connection no water should be going to the fresh water holding tank. In some cases these connections could be in separate compartments.

Hopefully this information has been helpful to you.

Do you have any suggestions or comments on this topic? You can add them to this page by clicking on the "Click Here To Post Comments" link located near the bottom of this page.

Happy RVing

RVing Al

Are You Looking For RV Parts, Accessories and Camping Supplies At Great Discount Prices? Visit Our RV And Camping Store.

I Love My RVing Website!!!!

Watch This Free Video To Learn How To Build Your Own Successful Website

Comments for How Do I Stop The City Water From Filling The Fresh Water Tank On My 5th Wheel Trailer?

Average Rating starstarstarstarstar

Click here to add your own comments

Bad Check Valve
by: Anonymous

Check Valve

I suspect you have a check valve in the water line that is leaking which would allow water to slowly leak back into the tank.

Same problem
by: Anonymous

I’m having the same problem on my new Forest River Sunseeker. I hook up to city water (I have a regulator on my hose) and it over fills my storage water, and puts out. The city water connection is on the back of the RV and the filling connector is on the right side. Please help.

Fresh water tank
by: Anonymous

I'm having the same issue. I used all the fresh water and turned my hose back on. It's hooked to the city water. But the fresh water tank filled right back up.

Had to re-plumb
by: Anonymous

Recently had water leaks in pex fittings changed to "shark-bites" and still some leaks my solution was going PVC starting at City water valve assembly after re- plumbing I did have a mix up in tank to City flow this I corrected but now have hot water flow but no cold and with only City flow and None with pump mode, pump runs, added filter took off bypass valve took out pump dissembled for obstructions and test water flow with bucket filled with water and made sure of no pressure leaks from all connections. STILL NO RUNNING "COLD WATER"?


I am haveing the same problem. I have on my motor home for 10 years and this week end it started it. Never done this before. I do have a pressure valev at the picket. My motor home is a 346 Georgetown Forrest river. 2003

water trouble
by: nancy Ralph

I am having the exact same problem. I am hooked up to city water because the water pump is broken, and the water is filling the holding tank and shooting out of the fill valve. HELP

by: Mountain Man

If you actually are connecting to your city water connection, it is possible water is being forced backwards through your water pump. Installing a check valve or replacing the water pump should solve this.
Are you using a pressure regulator. Maybe the city water pressure it high enough that this problem could be fixed by having a pressure regulator that you should have anyway.

Click here to add your own comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Ask An RV Question.

Get Your Article Published on Everything About RVing

If you have written an article about RVing, Camping or the Great Outdoors and you would like us to publish it on Everything-About-RVing.com, please visit our Submit An Article Page.


Over 1,500,000 successful roadside rescues—Good Sam RV Emergency Road Service

Camping World

Good Sam Travel Assist: Emergency coverage for you, your family, and pets. Plans Starting at $59.99 Shop Now!