$25 part wreaked havoc on our RV

[TXAggie00]

Welp, we had a fun weekend...

We are full-timers and as I was going through the routine of emptying tanks, I noticed a slow drip under the door. After inspecting it further I then noticed a bulge in the underbelly cover. After pushing on it, I realized it was water, so I pulled the liner from the edge and the water came pouring out. The initial drip was coming from the storage under the front section of the 5th wheel and it ended up having lot of water in the storage area (we sacrificed about 28 rolls of toilet paper which probably helped soak up a lot of the water) and after pulling off the cover exposing the wiring and plumbing we discovered the issue. It turned out that the blank tank flush has a vacuum breaker check valve that was faulty and every time we flushed the black tank, water went everywhere in the closed off section of the storage area. There are some spots showing sign of mold starting, so this must have been going on a while while the issue only continued to get worse.

Long story short, we aired out the RV over two days and replaced the part (which delivered the next day), but realized we need to be more proactive in case something like this ever happened again. We ended up buying a $12 leak alarm. I feel like we got lucky that we didn't suffer any major damage, so this thread is more a cautionary tale with some helpful advise. I would recommend installing these alarms in areas that often go overlooked, but could end up causing a much bigger headache (especially in areas with water appliances that are hidden out-of-sight).

Here is the alarm we installed next to the valve that was faulty (this is the new one). The contacts have a 6' wire, so we mounted the alarm close to the top so we could hear it and also make sure it stays put while traveling. The contacts were mounted on the floor where most of the water was located and right next to the water heater and water pump.


Hopefully this helps someone in the future!
- Scott

[bubbles]

Every installation procedure for that valve (that I've read) says it shall be mounted at least 6 inches above the highest flood level rim of any fixture connected to the waste holding tank. In my unit that is the top rim of the toilet and that's why it is mounted 6 inches above that within the coach interior (washer/dryer provisional compartment). If yours is mounted in a baggage compartment below the floor and factory installed it would appear the reg was not followed.

[5picker]

There are MANY threads on R/V forums about this vacuum break/check valve leaking and flooding the R/V. Sorry you had issues and didn't realize it.

While leak detectors are a good thing, replacing the inexpensive plastic valve with a quality brass valve is often suggested.

I too am interested to know if the valve in your compartment is located below the rim of the toilet? If so, I'd be contacting the factory. Here are the instructions, read #2.

[TXAggie00]

Thanks for the replies! I am in a 5th wheel and that valve is located just under the front section decking, which is 26” above the main floor decking. We have a single bathroom on the main floor and the rim of the toilet is 17” high, so we appear to be within specs. Keep in mind this was not an overflow issue, but a faulty valve with water pouring out the relief. Possibly a bug got in there, who knows, but if it was a critter that fouled the valve membrane, not sure the material of the outer valve would have made a difference, but I will certainly look into a stronger material. As this is our first RV, never even gave this valve a second glance, so this is more of a caution for new owners who may not have the knowledge the two of you do.

Thanks,
Scott

[TXAggie00]

Okay, so I was curious what exactly happened to the old valve since, mechanically, it’s a pretty simple device. It appears my initial assessment was correct, a bug carcass was sitting on top of the valve preventing it to seal correctly. Regardless of the material, this issue could occur, so, again, an detection device to moisture would be critical. This is a vacuum check valve, which implies that the top has to be open to normal air, so I have to believe any small critter could get in there and cause the same issue. I have attached the old valve where I removed the top cover. It’s blurry, but you can see the remnants of, what appears to be, a spider. I may wrap some screening around the new one to make sure this doesn’t happen (or at least reduce the chance.

Thanks,
Scott

[bubbles]

When pressure is applied that flapper/disk is supposed to seal off the vacuum breaker portion (open to ambient) of the valve (it's free floating). The check valve portion is typically a spring loaded ball bearing on the output side that opens with pressure and closes when pressure is removed. The vacuum portion is there so the valve cavity and input tubing can drain back out the input port (it's not black tank water). My first post shows I'm not familiar with the layout of 5th wheels.

[TXAggie00]

Originally Posted by bubbles

When pressure is applied that flapper/disk is supposed to seal off the vacuum breaker portion (open to ambient) of the valve (it's free floating). The check valve portion is typically a spring loaded ball bearing on the output side that opens with pressure and closes when pressure is removed. The vacuum portion is there so the valve cavity and input tubing can drain back out the input port (it's not black tank water). My first post shows I'm not familiar with the layout of 5th wheels.

Yep, exactly (I misunderstood the vacuum portion of the valve on my previous response, but understand now how it works). When flushing, water pushes up on the valve and should seal. The problem is the insect carcass blocked the seal and caused a leak through the top ambient opening.

Case in point, I’ve attached a picture of the valve in the flow position ( flushing black tank) and you can see the bug causing said leak.

This can honestly happen to anyone, and my entire point of this post is to make sure you can be aware of this type of issue before detrimental damage can be done. Put in leak alarms and be aware of what could very easily happen, thanks to real world experiences.

Thanks,
Scott

[SetauketJeff]

How does your leak detector work? The ones that I'm familiar with have two contacts on the bottom of the unit. When they come in contact with water, the circuit is complete and the alarm is activated. If yours is one of those, it needs to be installed upright in the spot where the water will pool.

[elchilero53]

Had something similar happen to us while on vacation this year. Flushed the black-water tank and my wife hollered there's water coming out from under the pantry door (which is opposite the BW tank clean out connector). Everything is behind a panel at the back that is held in place by screws. I will check it out when I work on trailer repairs this Saturday. Hopefully, it won't be too onerous. This has been a really good trailer.

[fishinfellow]

I use that type water alarm in our condo, in the closet that the water heater is in. They are usually under $15.00 at big box stores. Our condo association also offers one called the "screamer" , never know when a leak will occur. Saves alot of water damage to the units below.

[TXAggie00]

Originally Posted by SetauketJeff

How does your leak detector work? The ones that I'm familiar with have two contacts on the bottom of the unit. When they come in contact with water, the circuit is complete and the alarm is activated. If yours is one of those, it needs to be installed upright in the spot where the water will pool.

Sounds exactly the same. The one I got is from The Watchdog. The bottom contacts are removable and has a 6’ extension so the alarm can be mounted separate from the contacts. You can see it it the picture. The alarm is mounted up high with a black cord coming out the bottom and you can barely make out the contacts that are fixed to the floor. Makes it nice in an RV, otherwise who knows where the alarm would end up after a travel day...

Thanks,
Scott

[Oklamartin]

Originally Posted by TXAggie00

…
This can honestly happen to anyone, and my entire point of this post is to make sure you can be aware of this type of issue before detrimental damage can be done. Put in leak alarms and be aware of what could very easily happen, thanks to real world experiences.

Thanks,
Scott

Thank you, Scott, for taking the time to post this issue you found and the fixes you applied! Pictures are also appreciated! It is a big help to many others who read these forum posts.
Mike

[tempestdriver]

This is a pretty common problem. I replaced ours with these.


https://www.amazon.com/gp/product/B00467HJBQ

https://www.amazon.com/Anderson-Meta...1WFAEKZ8JMM4Z1

https://www.amazon.com/Valterra-P234...1WFAEKZ8JMM4Z1

[Celticrider]

One thing I’ve found is that some RV,s maybe not all,the black water drain valve has to be open while flushing.
I’ve did mine closed for a while thinking it would flush better,then all of a sudden noticed a leak under the sink.
I took the vacuum breaker apart but found nothing wrong with the way it worked.
It was then I read the warning label that I overlooked , or thought I knew better about making sure the drain is open to use the flush.
I reinstalled the breaker valve and used it since ,the way it is supposed to be used, at least on our Lexington, and it’s been leak free. The Lexington had a brass valve from the factory , not a cheap plastic one.
Thinking it was building too much pressure for the valve to seal?

[johnbryanpeters]

I relocated the valve to inside the shower where it will do no damage if it vents.

[61Tele]

Originally Posted by johnbryanpeters

I relocated the valve to inside the shower where it will do no damage if it vents.

I used two $0.50 clamps and a connector, and relocated the valve to the trash can.

Originally Posted by Celticrider

One thing I’ve found is that some RV,s maybe not all,the black water drain valve has to be open while flushing.
I’ve did mine closed for a while thinking it would flush better,then all of a sudden noticed a leak under the sink.
I took the vacuum breaker apart but found nothing wrong with the way it worked.
It was then I read the warning label that I overlooked , or thought I knew better about making sure the drain is open to use the flush.
I reinstalled the breaker valve and used it since ,the way it is supposed to be used, at least on our Lexington, and it’s been leak free. The Lexington had a brass valve from the factory , not a cheap plastic one.
Thinking it was building too much pressure for the valve to seal?

The reason for the warning label is so you don't get distracted while flushing / filling with the main valve closed and end up shooting the dreaded poopy water fountain out the tank vent of the roof of your rig. The tank can't build pressure due to the vent, which is why it's there. Now you always have the possibility that the manufacturer forgot to connect the vent, or put one in, or it's clogged with debris from the build, anything can happen the way they (manufacturer, not the vent or valve) operate.

[WNY_Clipper]

Originally Posted by Celticrider

One thing I’ve found is that some RV,s maybe not all,the black water drain valve has to be open while flushing.
I’ve did mine closed for a while thinking it would flush better,then all of a sudden noticed a leak under the sink.
I took the vacuum breaker apart but found nothing wrong with the way it worked.
It was then I read the warning label that I overlooked , or thought I knew better about making sure the drain is open to use the flush.
I reinstalled the breaker valve and used it since ,the way it is supposed to be used, at least on our Lexington, and it’s been leak free. The Lexington had a brass valve from the factory , not a cheap plastic one.
Thinking it was building too much pressure for the valve to seal?

There shouldn't be any back pressure if the valve is closed, if the Black Tank is vented properly...

[emm-dee]

Originally Posted by 61Tele

I used two $0.50 clamps and a connector, and relocated the valve to the trash can.

Guaranteed leak free valve.

[phipps33]

Originally Posted by emm-dee

Guaranteed leak free valve.

Exactly what I did when mine decided to start leaking. No problems since. LOL

[smittyboy]

I wonder if you could wire in a light, that you could install in the control panel, where your ceiling light switches are. That would light up when the alarm goes off, on the off chance that you may not hear the alarm.