Water tank issue-fresh water tank filling

[claywilson1981]

New to RVing and just bought a used Wildwood Heritage Glen 5th wheel.

Not sure if this is normal but wouldn't think it is.I drained the fresh water tank before I ever hooked up the water to it. I noticed the next day after hooking hose to city water hookup that the fresh water tank is full. There is a tank fill hookup next to the city water hookup. Did I do something wrong? Wouldn't think the tank would fill unless I connected to that port.

[kenandterry]

I’ve seen others report this same situation, but I’m not sure I understand the suggestions on how to fix it. I think it has something to do with a back flow valve.

I believe they suggest using your onboard water for awhile, using your onboard pump from a number of your taps.

Somehow, I think it corrects itself, but I’m sure someone else will chime in.

[Mr. Dan]

This appears to be a common problem — reported here weekly. It’s usually caused by a stuck check valve internal to the fresh water pump - or the check valve has debris in it holding it open. Scan down through this water system sub-forum where the site team moved your thread - see if you can find a similar title and read for remedies.

[Chuck_S]

Some trailers will automatically fill the fresh water tank while they're connected to city water. Some by design. Others by malfunction of check valves. Model year will help determine if this is automatic and what valves and check valved need to be checked.

-- Chuck

[claywilson1981]

Originally Posted by Chuck_S

Some trailers will automatically fill the fresh water tank while they're connected to city water. Some by design. Others by malfunction of check valves. Model year will help determine if this is automatic and what valves and check valved need to be checked.

-- Chuck

Thank you. It's a 2017 Wildwood Heritage Glen HyperLite 368RLBHK

[5picker]

Originally Posted by claywilson1981

Thank you. It's a 2017 Wildwood Heritage Glen HyperLite 368RLBHK

As mentioned, often a common issue caused by a malfunctioning check valve in the water pump.

BUT... it can also be caused by other things such as a wet bay (water hook up area) where the valves are configured incorrectly, connecting to the incorrect water port, a Showermiser valve in the incorrect position, having the pump turned on while on city water or even excessively high city water pressure (without the use of a pressure regulator) overcoming the pump's otherwise normally operating check valve.

Tell us more about your water system and how you use it.
Not all R/vs are configured the same and Forest River uses several different configurations of how water is supplied to the R/V.

We need to know how YOURS is configured so we can do more than just guess.

[Larry-NC]

Originally Posted by claywilson1981

New to RVing and just bought a used Wildwood Heritage Glen 5th wheel.

Not sure if this is normal but wouldn't think it is.I drained the fresh water tank before I ever hooked up the water to it. I noticed the next day after hooking hose to city water hookup that the fresh water tank is full. There is a tank fill hookup next to the city water hookup. Did I do something wrong? Wouldn't think the tank would fill unless I connected to that port.

Since you're new to this, it may not be obvious to you that the "check valve" everyone is writing about is really a one-way flow valve in the pipe. Water can flow one way, but not the other.

It's often constructed as a pipe fitting with a metal ball and spring. The ball and coil spring are coaxial with the pipe. When water pressure pushes against the ball, it compresses the spring and water can flow around it. When water pressure is from the other direction, through the spring, it pushes the ball against the pipe opening and no water flows through.

The RV plumbing system has two sources of pressure, the water pump and the city water connection. Each has a check valve. If either one is on, water would flow out the other if the check valves weren't present.

The check valve at the water pump on your RV is leaking. There are a couple of causes:
1) You've turned on the water pump AND city water. Don't do that. If you do, it puts pressure on the check valve from each side, counteracting the spring and reducing its effectiveness.
2) There's a tiny grain of sand stuck in the check valve. (All water has tiny particles in it, it seems.) Standard practice is to
--Turn off city water.
--Turn on pump.
--Run water in several on-off cycles to flush the particle out of the check valve.
--(Optional) Continue running water from the fresh water tank until it is empty. This serves to flush the valve further, and consumes the water in the tank.

[NavyLCDR]

Originally Posted by Chuck_S

Some trailers will automatically fill the fresh water tank while they're connected to city water. Some by design. Others by malfunction of check valves. Model year will help determine if this is automatic and what valves and check valved need to be checked.

-- Chuck

I have never seen, nor heard of nor read about before this post an RV that automatically fills the freshwater tank from city water.

Some RVs have valves on their water control panels that allow filling freshwater from city water connection. Some RVs have shower miser valves that cab be used for that purpose.

But I have never heard of an RV that fills freshwater tank automatically. Can you provide one example please? Or at least share where you gained this information from?

[NavyLCDR]

Originally Posted by Larry-NC

Since you're new to this, it may not be obvious to you that the "check valve" everyone is writing about is really a one-way flow valve in the pipe. Water can flow one way, but not the other.

It's often constructed as a pipe fitting with a metal ball and spring.

The check valve that most people are talking about here is internal to the pump diaphragm and not in a pipe fitting. Nearly all RVs from the factory rely upon the pump's internal check valve to prevent backfilling the freshwater tank from the outlet side of the water punp.

[doanshop]

Originally Posted by NavyLCDR

The check valve that most people are talking about here is internal to the pump diaphragm and not in a pipe fitting. Nearly all RVs from the factory rely upon the pump's internal check valve to prevent backfilling the freshwater tank from the outlet side of the water pump.

2X on that. That is one reason I use a water filter to try and stop any contaminates form getting into water system and causing this problem.

[Mr. Dan]

Originally Posted by NavyLCDR

The check valve that most people are talking about here is internal to the pump diaphragm and not in a pipe fitting. Nearly all RVs from the factory rely upon the pump's internal check valve to prevent backfilling the freshwater tank from the outlet side of the water punp.

I believe the dime size round valve inside and to the top of the large inner circle is the check valve in the pump head I’m replacing. My pump wasn’t letting water leak by into the fresh water tank; it just wouldn’t pump. I always use an adjustable water pressure limiter but I seldom use my water pump. This valve and its O-ring were stuck in the valve seat (hot Texas weather and no use?). When I tried to fix it, I fixed it so that no one could fix it!

[Mr. Dan]

I think these instructions are funny!