Fresh Water Tank Goes to Full All by Itself

[Chrisc40]

When I hooked up to city water I had 1/3 of a tank of fresh water on board. Now I have a full tank after 5 days. I did not fill the tank and now it's full?

Here's the specifics:
1. The indicator says the tank is full and I went outside and found it was full to tje top and dripping slowly.
2. The water pump has been off the entire time and we've been only using city water.
3.I have a water pressure regulator in line so there's no high pressure issues.
4. I have a 3050s Sunseeker 2017.

Anybody have this happen or know what could be going on?

[karrun]

Isn't there some kind of check valve to ensure that water won't flow back into the tank? My guess would be a bad check valve.

[A32Deuce]

Easy fix. Turn off outside water source. Relieve pressure in system. Turn on water pump and run some water for a couple minutes. Turn off pump and turn back on city water. You can drain your tank and see if it fills. There is a check valve at the water pump to prevent water filling the tank. If you connect city water and pump is on and run water, sometimes the valve sticks. Could also be a bit of construction junk in the valve. Once should do it. Had it happen once.

[5picker]

Originally Posted by A32Deuce

Easy fix. Turn off outside water source. Relieve pressure in system. Turn on water pump and run some water for a couple minutes. Turn off pump and turn back on city water. You can drain your tank and see if it fills. There is a check valve at the water pump to prevent water filling the tank. If you connect city water and pump is on and run water, sometimes the valve sticks. Could also be a bit of construction junk in the valve. Once should do it. Had it happen once.

^^This^^

Seems to be more common than ever.

[RV_Fan44]

Originally Posted by 5picker

^^This^^

Seems to be more common than ever.

+2

[Chrisc40]

Originally Posted by A32Deuce

Easy fix. Turn off outside water source. Relieve pressure in system. Turn on water pump and run some water for a couple minutes. Turn off pump and turn back on city water. You can drain your tank and see if it fills. There is a check valve at the water pump to prevent water filling the tank. If you connect city water and pump is on and run water, sometimes the valve sticks. Could also be a bit of construction junk in the valve. Once should do it. Had it happen once.

Thank you. I figured it was a check valve but wanted to get advice before tearing into it. I've been running on board water to lower my tank level for travel purposes and moving to another CG. I'll let you guys kniw how it turns out.

[5picker]

Often times it is dirt or debris that causes the check valve to stick but I'm seeing a trend where if the water pump is turned on along with the city water connection being on... and... if the city water connection has higher pressure than the pump output, the city water pressure will overcome the check valve and continue to hold it open even after the pump is turned off.

If you are at a rally where hundreds can be on the same water line and the pressure is horribly low, supplementing the city water with the on-board tank and pump can be a good thing. But not when the city water pressure is higher.

[A32Deuce]

This is true!

[Dano1955]

I was under the impression you shouldn't run pump while on city water. Did I misunderstand?

[5picker]

Originally Posted by Dano1955

I was under the impression you shouldn't run pump while on city water. Did I misunderstand?

Under normal circumstances, no you shouldn't.

But again, if you are at a rally or a campground where city water pressure is a mere trickle, supplementing with the on-board pump can work. Of course, you have to have water in your fresh tank to do it. And, you could always turn off the city supply and just use the pump too.

[A32Deuce]

I have been camping where water pressure gets really low so use pump to get better pressure. You need water in your tank first. Helps with showers. Just turn it off when done and make sure tank is not refilling itself.

[Goat Man]

We use city water until the tank fills, then we turn it off and use the pump until the tank empties, I have tried the remedies mentioned, but they didn't work.

[wnelsonfl]

I had this problem many times. We're is the valve and what does it look like?

[jackconn]

We had the same thing happen. I didn't notice the tank was full until after a 3+ hour drive
(never bother checking the tank level since we are usually on city water) and, after reading a horror-story thread on this forum, also saw that the front tank support bar was bent a little. Lucky we didn't have a disaster but was then careful to always drain whatever had accumulated in the tank before hitting the road. Ours didn't fill quickly - overnight was about 1-2" in a 30 gal tank.

Back from the long trip, dropped the TT at the dealer yesterday for minor work including fixing the check valve (most likely by replacing the pump assembly) and tank support.

Interesting suggestion to try to flush out or "reset" the check valve - great idea for the road. I've also asked the dealer to install a shutoff valve in the right spot (probably inline with the pump) to allow me to manually close that line when we're are on city water for an extended time. This way if the check valve ever stops checking again, I've got an easy fix. (We don't boondock often.)

[5picker]

Originally Posted by Goat Man

We use city water until the tank fills, then we turn it off and use the pump until the tank empties, I have tried the remedies mentioned, but they didn't work.

Some units... have a valve that you turn to fill the fresh tank from (and while) connected to city water. They do not have a gravity fill port. The hose connection is a single common port and there is knob (usually a blue) that must be turned to direct the flow from entering the plumbing or switch to filling the fresh tank.

Is it possible yours is this way and you are filling the tank from the city port and not turning the valve off once full?

[5picker]

Originally Posted by wnelsonfl

I had this problem many times. We're is the valve and what does it look like?

The check valve is built into the pump head.

[A32Deuce]

Originally Posted by Goat Man

We use city water until the tank fills, then we turn it off and use the pump until the tank empties, I have tried the remedies mentioned, but they didn't work.

It would help if you said what type unit you have so that people with the same type can help. Some fixes are universal, others are unit only.

[Big Bill]

I have a cedar creek , it took 4 months to fill mine , my tech changed the selector valve what says city water or tank fill , it hasnt filled yet but it hasnt been 4 months

[kenword]

I had the same problem and there is a value right by the pump that was partially open, running water into the fresh water tank. I turned the valve and closed it and that solved the problem

[5picker]

Originally Posted by kenword

I had the same problem and there is a value right by the pump that was partially open, running water into the fresh water tank. I turned the valve and closed it and that solved the problem

I'd be interested in knowing what unit you have and what valve it was by the pump?

Unless it is the fresh fill valve I mentioned earlier (and not usually by the pump) typically, the only valve installed near the pump (unless done aftermarket) is the pump's suction side selector valve for the winterizing port or fresh tank.

Turning this valve would divert any back flow through the pump's internal check valve to go either to the fresh tank (filling unwanted) or allowing it to seep out the winterizing/antifreeze port. Neither being acceptable.