Used Black Tank Flush Connection Water in RV Bathroom

[josh409]

Hello,

Got an odd problem that maybe someone can explain or help with. This is my first post… this site is great! Also, new to RVing

We purchased a brand new 2016 Keystone Passport 2400BH which we love. We took it out on our first RV trip, and everything went smoothly until I hooked up the Black Tank Flush port. Please note, we took the RV out in beginning of April in PA, and mother nature decided to be cold and snowy..not ideal conditions for the first RV trip, but the 2016 Keystone Passport 2400BH has extend season camping with a fully enclosure under belly and insulated as well. This information may play into what happened…We’ll see…. The night prior to leaving I disconnected the city water lines, and filled the holding tank up some due to the temperature dropping into the 20’s, and closed the Gray water tank to use the gray water to flush the sewer line. The morning of leaving opened the Black tank to dump all the waste water out. No issues with this… The gray tank is still closed. Then I closed the black tank. Took my garden hose (not the fresh water hose) I have two hoses one for fresh water, and one for the Black water flush connection on the side of the RV. Connected the Garden hose to the Black water flush connection on the side of the RV, and connected the other end to the parks city water connection with a pressure regulator, turned on the water, and as soon as I turned on the water, “some” water was spraying back out at me, but not a lot… Here is the issue… My wife was in the bathroom of the RV when I was flushing the black tank, and water was coming from, “Around” the bathroom sink… Note, the Black water tank flush connection is on the outside of the RV right by the Bathroom sink. Now, I didn’t see, “exactly” where it was coming in from, but water did indeed come in. Also, note there is a vent under the sink, so I am not sure if that is where the water was coming from or not… I noticed the vent days after this happened. As a reminder, I did have the black tank connection closed when using the black water flush connection. I’ve done research on the internet…to get the black tank nice and clean its best to keep the black tank closed when cleaning when have the Black Tank flush connection on. Once water was coming into the RV’s bathroom I immediately turned the City water off, and opened the gray tank to flush the sewer line. I didn’t get the black tank as clean as I would have liked. This is the first time we took the RV out, so I confused on exactly what happened. I was thinking the weather, “may” have played a part in this, but I am not sure…. We are taking the RV out at the end of May, so the first thing I am going to test the Black tank flush connection. I know this is a lot of details, but my question is how can water from the black tank flush connection get into the RV? Something got frozen due to the weather? Some piping, check Valve, or something else is bad?

[lynnmor]

The "vent" you are seeing is a vacuum breaker installed to meet code. They don't work and are to be installed where leakage won't be a problem. RV manufacturers cannot read and install them wherever they please. Just eliminate the stupid thing.

http://www.bandbmolders.com/files/Th...2_Install_.pdf

Don't use a pressure regulator to flush the tank for maximum cleaning.

Don't leave the black tank valve closed while flushing. You may close it for a short period of time to partially fill the tank, but don't leave it unattended.

[jason_sos]

I thought that I read somewhere (it might even be a sticker on my trailer), that you should leave the black water valve OPEN when doing the flush, otherwise, pressure will build and it can cause issues. The flush is a sprayer that sprays around inside the tank - you shouldn't need to fill the tank to flush it.

[josh409]

Originally Posted by lynnmor

The "vent" you are seeing is a vacuum breaker installed to meet code. They don't work and are to be installed where leakage won't be a problem. RV manufacturers cannot read and install them wherever they please. Just eliminate the stupid thing.

http://www.bandbmolders.com/files/Th...2_Install_.pdf

Don't use a pressure regulator to flush the tank for maximum cleaning.

Don't leave the black tank valve closed while flushing. You may close it for a short period of time to partially fill the tank, but don't leave it unattended.

Thanks for the pressure regulator idea... Will take it off for sure next time. I understand that you should NEVER leave the black tank closed for any extended period of time or leave it unattended. The water that was coming inside the bathroom started pretty much immediately when I had the Black flush connection turn on, so the Black tank didn't really have any time to fill up. Still wondering, "how" the water from the Black Tank Flush connection made it into the RV from under the bathroom sink..

[josh409]

Originally Posted by jason_sos

I thought that I read somewhere (it might even be a sticker on my trailer), that you should leave the black water valve OPEN when doing the flush, otherwise, pressure will build and it can cause issues. The flush is a sprayer that sprays around inside the tank - you shouldn't need to fill the tank to flush it.

Jason,

That totally make sense now!! I think this, "could" have caused the water we are seeing.. I have to see if my TT has a sticker on it I cannot remember. I guess when, "Googling", "how to flush black tank correctly".. doesn't always apply to all TT

[BillJinOR]

Holding tanks have large vent pipes running from the top of the tank to the roof. Pressure can't build unless that vent pipe is blocked ! Leaving the drain valve closed until the tank has a substantial amount of water is the proper procedure. Leaving it open does little good to flush the solids out. As said watch and don't walk away as water could fill the tank and run up the vent and out the roof or leak at the toilet seal as the water level goes above it ... Not good
As already noted the leak you had must be the back flow valve leaking which is required to prevent sewage from back flowing into the park water system normally they should not be inside but who knows.

[mel s]

Originally Posted by lynnmor

The "vent" you are seeing is a vacuum breaker installed to meet code.
Just eliminate the stupid thing.

lynnmor
That "vent" is NOT a "vacuum breaker"...It's an AAV, (air admittance valve):


Because it IS "installed to meet code" it is necessary and should never be eliminated.

Mel
'96 Safari

[rideandslide]

Here is our procedure, if flushing is not available at the dump station, at lot of parks we go to only have a cut off end on the hose ( i think to prevent flushing to save tank capacity, which i understand ) . When home ( we have a few acres in the boonies ) i hook up the flusher and fill the tank to about 2/3 full and flush, do that a second time, all the while the flusher is on. Once done, add some water back in the tank, with a bag of chemical, till next trip .


Never seen water inside !!!!

[lynnmor]

Originally Posted by mel s

lynnmor
That "vent" is NOT a "vacuum breaker"...It's an AAV, (air admittance valve):

You are talking about oranges, I was talking about apples. If you would have clicked on the link, you would have seen the parts that make up a flusher.

On the 4th page it says this:

*Important**!
Make sure faucet is open completely during entire tank flush cycle. Vac/Check is designed to work at water
pressure range of 8 – 125 psi. Water leakage from Vac/Check is likely when water pressure in supply line is
under 8 psi. It is normal for a small amount of water to escape Vac/Check as plumbing line for tank flush
pressurizes

[BFlinn181]

I agree with Mel S, the 'cheater vent' is necessary and shouldn't be eliminated. Without that vent, water could continue down the drain in the sink and empty the trap, allowing sewer gas back into the trailer. The AAV allows air in but stops the gases from escaping, when they work properly. A sewer smell in the cabinet means the valve has failed and needs replacing, not eliminated.

If the black tank was too full when you started flushing, it would normally overflow into the shower or tub drain, the usual lowest drain in the camper. I think your leak can be tracked down to be a cracked or bad connection at the flush hose connection. I'd get rags and a light and be under the sink while your wife turns on the hose. You should be able to find the leak. I wouldn't use the flush valve until it gets repaired, water can cause damage to interior plywood or particle board, a favorite material in most trailers.

Starting the black tank with some water and only dumping when it's full or close to it, is the way to properly deal with black tank. Flushing can help, but unless you crawled up in the tank with a pressure washer you won't get it as clean as new.

Call your dealer's service department and get scheduled for a warranty repair if you don't fix it yourself.

[1bigmess]

Mine leaked when using the black tank flush. It was cross threaded. I carefully disconnected it, checked all the threads, and carefully reconnected it again. It works fine now with no leaks.

[josh409]

Originally Posted by BillJinOR

Holding tanks have large vent pipes running from the top of the tank to the roof. Pressure can't build unless that vent pipe is blocked!

This could be True because there was a, "good" couple of inches of Snow on top of the RV roof. I am not sure, "how" long the vent pipe is on top of the RV.

[josh409]

In Reading the thread it appears the issue is either the vent pipe was blocked, the Black flush connection is broken, or like someone in the thread said the Black tank must be opened to use the Black tank flush connection due to pressure build up. While I agree from reading filling up the black tank with, "some" water, and don't walk away is the proper to clean a black tank. I'll found out here within a week I am hoping it's the Vent pipe or the black tank needs to be opened, because it's brand new hate to have a repair already, but it's covered under warranty, though the place is two hours away from my house to get repaired.

Thanks for everyone's help! I was hitting my head on the desk to try to come up with, "what" was causing this occur.

[BFlinn181]

The black and grey tanks usually have a roof top vent, some may be joined to only one vent, but not usual, I think. It looks like this:
CAMCO RV 40032 - Camco RV Plumbing Vent, 2-1/2", Polar White 40032 - RV Plus

If the vent were blocked, putting water in the tank or emptying it would cause the tank to 'oil can' before pressure would build up and cause a leak out the AAV. I'd really look for a loose or leaking fitting or split line from the tank flush connection.