Water entering gray water tank under pressure

Tinnitus

Here’s the set-up: 2020 T@B 400 that I've had and used for more than a year. Three-night stay at a full-hookup RV resort. Water hose and brass in-line pressure regulator that I’ve been using for a year without issue hooked up to the resort water system, with the regulator, of course, at the source end of the hose.

We had one night at one site. Our only water use was to wash a few dishes in the evening and the next morning for two people. I emptied the gray water tank the next morning. and did not notice anything unusual. 

So, on to the second campsite, same RV resort, for nights number 2 and 3. Same deal. Water usage confined to washing a few dishes for two evenings and one morning for two people. (Showers, toilet, etc., at the resort’s very nice bathhouse.) I did not empty the gray water tank on the first morning at the second site, because I’ve never had to do it daily for this kind of usage in the past. The gray water tank had previously never came close to being full after two days of light dishwashing.

At around 4:00 am on the second night in the second site (third night of camping), my wife awaked me and said she could hear “gurgling”. Once awake, I could hear it, too, coming from the right rear area of the trailer. 

I got up, lifted the lid of the kitchen sink and found it full of water, just shy of the top. (The sink plug was being stored in the cutlery drawer.) I lifted the faucet up and determined that no water was coming out of it, and the faucet handle was in the full closed position. 

There was a small amount of water puddling up from the drain in the shower, but no water was flowing from the shower head or the shower sink faucet, and both handles were in full closed position.  

I went outside with a flashlight and found water dripping onto the ground from the right rear of the trailer. 

I immediately turned off the resort water at the tap and the sound of the gurgling inside the trailer stopped. 

I opened the valve for the gray water tank and it was like releasing Niagra. Never, in my year of owning this trailer has there been that much water flowing out of it, and as I said, this was after a mere two evenings and a morning of light dishwashing. 

The kitchen sink drained itself with the emptying of the gray water tank. And remember, the sink is much higher than the floor of the shower. The puddled water in the shower never came near the edge of the pan. 

Okay, so with all faucets in the full closed position, water was entering the gray water tank to the point where a column of water rose up into the kitchen sink (but not over the edge), and was leaking out into the body of the trailer somewhere. (I went over every place I could access with a flashlight, but I can’t figure out exactly where that leak was.)

How did this happen? 

What should I look for?

 

qhumberd

My thought would be to start over with your grey tank empty, and all faucets off and turn on the resort water and listen for water flow. After it pressurizes, there should be no flow or sound. Make sure the water pump is OFF. As I understand the 400 plumbing, the only way to the grey tank is from one of three drains in the trailer (sink, shower pan and shower sink. The intake hose into the trailer is under the closet (unless you have the larger frig), so that is where I would listen when re pressurizing the lines. The water had to make it to one of those 3 drains.

rh5555

I'm puzzled as to why the water did not back up in the shower pan, but did in the sink.  On my 2020 TAB400, the sink has a Hepvo trap (which should never allow reverse flow) and the shower has a regular U trap (which allows reverse flow with no restriction).

Recognizing that builds change within model years, could you verify that the traps as as described.  You can see under the shower pan from within the trailer by removing the inspection panel.

The Hepvo trap looks like this:

Tinnitus

rh:

My trailer is in storage a few miles from here, and I seem to recall that there is some sort of special trap under the kitchen sink, but I don't recall the name. It would have been nice if it had stopped reverse flow, but it still doesn't tell me what happened. 

qhumberd: I'm afraid I don't follow you. How could "city" water enter directly into the drains, bypassing the faucets and shower head?

I'm not saying it didn't, but how can that happen?

Tinnitus

rh:

I see you added a photo to your post. Yes, that looks like the trap under my kitchen sink. 

Sharon_is_SAM

I recall a 400 kitchen faucet that can accidentally turn on and fill a gray tank.  I think it was the faucet that folded into the sink.
We always turn off the water supply at the spigot when we leave the area.  But, if you use the toilet at night, I can see leaving it hooked up.

Tinnitus

Sharon, you can believe I'll be turning off the source spigot at night and when not at camp from now on!

But as for the kitchen sink, I confirmed at the time that I discovered the problem that the faucet handle was full-shut, and no water was coming out of the faucet itself. Same with the faucet in the shower and the shower head. 

rh5555

@Tinnitus: was your second camp site at lower elevation than your first?

Tinnitus

rh:

No, second camp site was same elevation. Memorial Day weekend. The RV resort (Ruby's Inn, Bryce, Utah) had to move us to a second site to give us the three nights. 

Gray water tank was drained after the first night just out of habit, because I was disconnecting everything. 

Bayliss

@Tinnitus, I agree with @qhumberd's suggestion for troubleshooting the source of the water.

Since you have a Hepvo on the kitchen drain, which should not allow water to back up into the kitchen sink if it originated somewhere else (i.e., the shower or bathroom sink), I would think that the water originated from the kitchen faucet.  However, your observations seem to refute that.  As for the kitchen sink and shower pan not overflowing, that may have been pure luck, since the gurgling sound may have tipped you off before that happened.

Was there any water in the fresh water holding tank?  Was the pump off?  [Not that it actually makes a difference, particularly since the water pressure from the campground would be greater than that produced by the pump.]

Figuring out where the water was leaking at the back of the trailer may be the key to solving the mystery.  (Keep in mind that the origin of that water may be further toward the mid or front sections of the trailer.  For example, maybe it was somehow coming from the overfilled gray water tank, or associated plumbing, and flowing along the path of least resistance toward the rear of the trailer.  That too might account for the kitchen sink not overflowing.)

Denny16

If the sink was backed up, it was because the drain was no longer allowing water to flow through.  The source of the running water has to be from the galley sink, Tinnitus you may have had a slow leak from the sink faucet, and when you picked it up to check, you turned the faucet back off without realizing it.  I did something similar, bumping the faucet lever when folding it back in, turning on the water a bit.  It does not take long for a slow leak to back things up with a small gray water holding tank.
cheers

Tinnitus

No water in the fresh water tank. I have never used the fresh water tank or the water pump, and it was definitely turned off. The switch is lighted, like the light switches, and it was off. 

"Tinnitus you may have had a slow leak from the sink faucet, and when you picked it up to check, you turned the faucet back off without realizing it."

I've fiddled with that faucet many times because the glass cover keeps banging into it. 

Before I left the trailer, I lifted the faucet up out of the sink to check for water flow. There was none. I check the faucet handle. There was no looseness. It was fully turned off. I was, by this time, fully awake and alert, too. 

Tinnitus

BTW, I've sent a copy of my original post to Nucamp with a request that their technical people consider it. It's out of factory warranty, but I have an extended warranty plan.

qhumberd

qhumberd: I'm afraid I don't follow you. How could "city" water enter directly into the drains, bypassing the faucets and shower head?

@Tinnitus This is indeed a puzzle but I agree with @Bayliss about also investigating the leak outside the plumbing to see where that originated. 

Since there was no water in the fresh tank the city water connection would have been the only source for the water and the overflow you experienced. So unless the lines connected themselves we have to accept that the city water got into the drains, filled the grey tank and backed it up. I have experienced many times closing the lid to the kitchen sink that I have touched the lever with the glass, causing some water flow that would be easy to miss. In your case the sink was nearly full with the glass down, and the faucet end would have been under water. At 4 AM did you close the lever as you were lifting the faucet? It may have been only slightly open to create the flow needed to fill the grey tank over several hours and the subsequent problem. If the source of the water was the kitchen faucet then the Hepvo trap had water coming from both sides, therefore it did not seem to work.

I know I am challenging your facts and not meaning to be disrespectful, just trying to make a hypothesis.

I'll be turning off my city water at night BTW based on your experience, so that is good at least. Glad you did not have more damage and that your wife woke up. BTW I never give my wife enough credit for the times she has saved us in some way.

Best wishes

ScottG

I agree with all of the above--something doesn't add up here.

I'm not very familiar with newer models or with 400s, but I'll offer this...

Is there a flush feature for the gray water tank? Is it operated via a Nautilus panel? If the answer to both is yes, check the valve positions on the nautilus carefully--it's possible you have been pumping flush water into your gray tank, which would certainly fill it up in a hurry.

Barring that there are a limited number of ways water can get into the gray tank: the three drains (as noted by @qhumberd), and possibly the vent where it exits the trailer (though that should be well protected from any water exposure).   

Michigan_Mike

I’ve had the same thing happen with the bathroom fold up sink.  The handle was bumped by the sink when it was stowed, we came back and the gray tank had filled up and water was overflowing out of the shower pan.  My guess is that this is an anomaly of sorts and your water originated at the kitchen sink.  👍🏻

Denny16

That is what I figured also, as previously stated.
Scott, the newer TaB400s with the Nautilus panel, do not have a gray tank flush, so no valve settings to create one.  They only have a black tank flush, while mount Ted on the Nautilus panel, does not route thrugh any of the vs,fres either, as it is a direct connection from the hose fitting to the black tank via a one-way check valve.  There are normally, no direct water inlet connections to the gray tank either.

The only way for water to fill the galley sink and gray tank without backing up the shower pan completely, is water went down the galley sink. The unvented HEPVO valve will stop draining when the tank fills enough to cover the tank airspace.  Hence the water in the sink thst did not drain until the gray tank was drained.

The only other explanation is the house elves had a party and used the shower and sink to clean up their mess whilst the OP slept. 

cheers

Bayliss

qhumberd said:

BTW I never give my wife enough credit for the times she has saved us in some way.

@Tinnitus, following @qhumberd's lead, I am giving my wife credit for this additional possibility:

The water pressure regulator may have failed and needs to be replaced.  It's an inexpensive item, so that's one thing I would do.  Initially, I questioned whether that could be the issue, but thinking it through, it seems very plausible.

IF the regulator failed, I could see the pressure slightly forcing open the faucet valve or exerting pressure on a seal to allow water to flow through the faucet.  PEX lines can withstand quite a bit of pressure, but they (or more likely, a connection between water lines) do fail when the pressure exceeds what it can handle.  This would also account for the water leaking under the trailer.

So, in line with the "path of least resistance" thought, what may have happened is that excessive water pressure due to failure of the regulator initially caused a slight, but continuous, leak at the kitchen faucet.  With the continued pressure not impeded by the failed regulator, a PEX connection could also fail (i.e., blow out), thus leaking significant amounts of unimpeded water flowing under the trailer (but above the coroplast covering the underside of the trailer) along its own path of least resistance, where it ultimately appeared at the rear of the trailer.

Therefore, it would be well worth your time to remove the coroplast (starting at the front of the trailer) to see if you can locate a disconnected, or burst, water line.  If you find that, I believe it will confirm that the regulator failed.

P.S.  @ScottG's suggestion regarding the Nautilus system is intriguing, but I too am not familiar with how it works as far as flushing/winterizing the holding tanks.  However, I would expect the Hepvo to prevent water from backing up from the gray water drain and up into the kitchen sink.

[SIDE NOTE:  If you do find a disconnected water line under the trailer, you can count your lucky stars, because that will have saved you from having a flooded trailer interior.  I previously posted an article about how much damage that can cause.  If I can locate that article link, I will post it here.]

ADDED:  Found this discussion regarding the possibility of interior flooding of a T@B 400 due to the faucet not being turned off correctly:

https://tab-rv.vanillacommunity.com/discussion/11913/question-about-the-400-flooding-from-kitchen-faucet

Denny16

Nice theory Bayliss, a failed pressure regulator could be then issue, and I agree is another plausible explanation. As for water under the trailer, the only plumbing connections under a 2020 TaB400 are the gray and black tank drains, along with the fresh water holding tank inlet connections on top he tank.  Not sure if the gray water tank has a top connection or side connection, but if the tank completely filled, the water could have come from his connection if it is loose.  Like you said, worth removing the plastic bottom cover to expose the gray tank connections and check.  

Water leaks inside the 2018-2020 TaB40Os are only going to cause some staining of cabinet base wood bits that may get wet, and possible wreaking of the linoleum flooring glue.  The floor on these models does not contain any plywood layers, and is a composite floor using a Azdel top layer over foam insulation (creating a soft feel to the floor) and a thicker composite panel on the bottom layer.  If it gets wet, it drys right out.  Water can only get into the foam layer from holes drilled through the floor for plumbing runs from inside to the outside for drains, and tank inlet connections.  All of these can also be sealed.  

So Bayliss, your explanation is very good and is likely what happened, and supports what Tinnitus said about the faucet valve being turned off, but water in the sink and draining from the back... and beats my house elves theory!  
cheers.

Tinnitus

Guys, thanks for all the responses. Forgive me if I don't respond to each of you individually. 

A failed pressure regulator had simply not occurred to me, but given the mysterious circumstances, I think a detailed examination of the entire water system is in order. I don't know if my extended warranty coverage will cover the cost of this, but it simply needs to be done. 

As for the kitchen sink faucet on the night in question, I was awake and alert by the time it occurred to me to look inside the sink to see if that was where the gurgling noise was coming from. 

With the water just shy of the top (and the drain plug safely stowed in the cutlery drawer, I reached into the water and lifted up the faucet, shining a flash light directly on the nozzle. No water was coming out of it. I reached back into the water to gently press on the faucet handle which was, and had been, in the full down position. By finger touch, I confirmed that it was fully pressed closed. 

I did the same shower head and bath sink. All closed, no water flowing from shower head or faucet. 

Re: flushing the tanks. I distinctly recall discussing this feature of the black water tank with the tech guy at the dealer where I bought the trailer. I'm certain he said the gray water tank did not have this feature, but I will check the manual later today to confirm that. 

BTW, don't be afraid to question any of this. My feelings are not easily hurt. 

Denny16

Tinnitus, you should first check the water pressure regulator valve to see if it is working properly.  You can get a hose connection type pressure valve , screw it on the hose bib at home, check the pressure, then put the regulator between the gauge and hose bib, and see if the pressure is less.  If yiur home pressure is 40psi or less, see if you can find a higher pressure hose connection to test the regulator.  If the regulator is OK, then spend the $ to have the rest of the system checked.
cheers

Tinnitus

Denny, even if the regulator is not okay, I'm definitely going to have the rest of the system checked. 

Denny16

That is probably a good idea, given the strange issue.  Checking the regulator, and if it is bad, would explain your mystery...
cheers

TNOutback

The gray water tank has an overflow outlet, which could account for the water leaking under the trailer (I know from experience).  I have a 2020 400 as well, so I’m very intrigued with this situation.  Given the kitchen sink was full of water, and there was water coming out from underneath the camper, I have to think the kitchen faucet had to be on for quite some time to fill up the gray tank.  The overflowing gray tank ran onto the coroplast bottom and found a path to the rear of the camper, where it was observed coming out.  Since there was no water running over the kitchen sink, the gray tank overflow was at least keeping up (at the point it was discovered) with what was leaking/running out of the kitchen faucet.  I don’t see any other plausible explanations other than a kitchen faucet that was accidentally left on or its valve failed.

This unfortunate situation is yet another reminder to all of us to turn off water sources when we leave the camper, and maybe while we are sleeping as well.

ScottG

Sounds like my gray tank flush theory was a red herring. I'm still unclear how water could be backed up in the kitchen sink but not overflowing the much lower shower pan--particularly since they gray tank apparently has an overflow.

I'm wondering if the water was simply pooling in the sink from a drip, and draining periodically into the tank. I'm not real familiar with the HEPVO valve, but I can see where it would require a certain minimal amount of fluid to open the valve. 

Again, just guessing here, but this would be consistent with the peculiar symptoms.

Bayliss

@TNOutback, I am aware that holding tanks need to be vented (i.e., to allow air to escape the holding tank as fluids/water enter the tanks.)  However, I am not aware of an overflow outlet (other than the holding tank drains) and have been unable to find any information online or on this forum.  Can you provide more details regarding what you are describing and the physical location of the overflow outlet?  A photo would be great.  Thanks.

I know it is configured differently for the T@B 400, but the photo below (previously posted by @BrianZ - - thank you!!) shows the black vent pipes for the T@B 320 S (green arrows show those pipes, which vent through the front driver's side of the trailer.)

Tinnitus

 "I don’t see any other plausible explanations other than a kitchen faucet that was accidentally left on or its valve failed."

TNOutback, if somebody had told me this story, I would have thought the exact same thing. 

Before going outside to turn off the water at the city tap, I lifted the faucet out of the sink and examined it under strong light. No water - absolutely - no water was flowing from the faucet. Not even a drip.

Same with the shower head and the bathroom faucet. No water flow. No drip. 

It seems implausible, I know. 

Insurance company says they'll cover, so my next step is to have a local dealer dig into the water system and see what's what. 

rh5555

I just queried Nucamp and got a quick reply from Raphael:

1. Q: Is the grey water tank vented? A: Yes the grey tank is vented.

2. Q: Does the grey water tank have an overflow, or does it back up into the trailer when full?  A: The grey water will back up into your shower when it starts to overfill.

3.  Q: Is there some kind of one-way valve to prevent an overfilled grey water tank from backing up into the shower pan?  A: No we do not have a way to prevent this.

This leaves the biggest puzzle still unanswered:  How could the grey water be backed up to the sink, and not flooding your shower pan first?

Late breaking thought:  Have you seen this post? @ChrisFix has a similar issue...

Denny16

First, yes the gray tank is vented, out the roof through the closet/3-way fridge option in the TaB400. 

Second, none that I have found.  The galley sink vent does terminate just below the counter, not sure if it is open or a syphon valve.  Yes, gray water will backup in the shower pan when full, had this happen to me. 

Third, on the newer TaB 400 (2020/2021), the galley sink does not have a traditional P/J trap, it has an HEPVO valve, that acts like a one way valve, and the galley vent was eliminated. When the tank fills, if pressure in the line increases, or water trying to get in the sink from the discharge pipe is blocked, and water stops draining from the sink, as the valve is closed.  

See: https://hepvo.com/
cheers

TNOutback

@Bayliss “overflow” may not be the correct word, and “vent” may be more appropriate.  However, on two separate occasions where I did not stay on top of my gray water content, I have negligently over-filled my gray water tank, and on both occasions water was pouring/dripping out of the coroplast bottom onto the ground.  At neither point did it back up into the shower pan before I noticed it, but it was clearly coming out from whatever opening there is on top of the gray tank, underneath the camper.  Based on my experience, I was surmising the “leak” underneath the OP’s trailer may not have been from fresh water piping, but that vent/overflow on the full gray water tank.

The fact that the OP’s kitchen sink was completely full of water while there was only a “small puddle” of water in the much-lower shower pan would seem to be gravity-defying if we are only looking at a full gray water tank backing up.  As mentioned above, I have think the under-sink valve is also part of the equation here.  Still remains though, how the sink got full of water in the first place?  It can only be Gremlins !

Sharon_is_SAM

I remember that the new 2021 fresh water tanks have a small overflow/air vent on top that can be blocked by insect webbing.  I wonder if the gray tank has the same kind of vent?