Black tank valve leaking?

[MaxwellD]

Greetings ,
I have a 2024 381 DB being lived in full time. On two occasions now, we are seeing water leakage apparently coming into the convenience center around the black tank valve handle (?) - can't tell for sure. The water is apparently a slow drip / slow leak and has saturated the bottom of the bulkhead and the immediate floor adjacent to ithe bulkhead in the baement. The water leakage has a faint septic odor. Emptying the black tank leaves us a little dissapointed in that the full "swoosh headwater" sound is not appreciated - in other words, it doesn't drain like a really full tank. The occupant is using a lot of water at each flush which should be a good practice. The black tank level indicators are already malfunctioning and it has shown the tank to be full almost after the first week of living in it. I am going to remove a bulkhead to look around behind the convenience center tomorrow. Does anyone have an idea of what may be going on? The grey valve adjacent to the black tank valve is left open.
Thanks,
Max

[Carl n Susan]

It is unrealistic for the black (or even grey) tanks to leak back through the pull handle. I suspect a cracked water line valve behind the convenience center wall. The leak should be obvious once the plastic panel is removed.

P.S. What is a "381 DB"???

[newowneroldmontana]

I've had an unexplained water-saturated area around my tank pull handles several times, too, and I haven't done anything about it yet, but I think I've finally figured out the problem--in my rig, I can see a large black pipe coming down through the ceiling/floor close to my tank pull handles. I think that must be the pipe that goes from the toilet to the black water tank, and I think I must either have a slight leak at the base of my toilet which sends a trickle of water down the outside of that pipe to drip down onto the floor near the tank handles, or I have a slight leak in the black pipe itself, at the fitting where it curves.

About your black water tank--I don't know whether it's emptying well or not, but I think everyone's black water tank sensors are useless. I think the sensors always tell you your tank is full because toilet paper and other stuff gets stuck to them inside the tank. I've read that some people use tank sensors which are mounted outside the tank, which work better.

[Mikendebbie]

Max - this sketch is probably not 100% accurate - but it should give you an idea for where to look for leaks.

Your tanks (front black and gray) are located somewhere in the front drop frame. I don't know the exact location or orientation. The Wet bay is also located on the floor of the basement/ top of the drop frame. I show drain pipes from the plumbing items above for illustration purposes - but I have no idea how they are routed.

As Carl said - it is highly unlikely that this is coming from the tank valve itself given that the valve is probably lower than the drop frame floor. Maybe there is a slow leak in the toilet drain pipe + dripping on the tank valve stem ???

You will get a better view of all of this when you remove the basement bulkhead wall.

[MaxwellD]

Originally Posted by Carl n Susan

It is unrealistic for the black (or even grey) tanks to leak back through the pull handle. I suspect a cracked water line valve behind the convenience center wall. The leak should be obvious once the plastic panel is removed.

P.S. What is a "381 DB"???

Sorry, I meant TB (2 bedroom model), thank you for the advice.

[MaxwellD]

Great side view schematic - I never had that straight in my mind till now. Has to be something other than the black tank pull valve, 'preciate it
(TAMU CVM '84)

[MandK]

I would start by looking behind the convenience center. On mine, it would be a very likely scenario for a water line to be leaking and dripping/running down to the tank pull.
There could be a threaded fitting directly above the black tank pull that just needs to be tightened up, hopefully.
You mentioned a very faint septic smell, the white line directly above my black tank pull is the black tank flush line. Maybe it??

[MaxwellD]

Originally Posted by MandK

I would start by looking behind the convenience center. On mine, it would be a very likely scenario for a water line to be leaking and dripping/running down to the tank pull.
There could be a threaded fitting directly above the black tank pull that just needs to be tightened up, hopefully.
You mentioned a very faint septic smell, the white line directly above my black tank pull is the black tank flush line. Maybe it??

That was it hopefully - the tightening collar on the black tank flush connection was finger loose. Four revolutions to tighten hopefully will have fixed the issue.
Thanks everyone for the input on this issue.

[Kyle and Lisa]

Originally Posted by MaxwellD

That was it hopefully - the tightening collar on the black tank flush connection was finger loose. Four revolutions to tighten hopefully will have fixed the issue.
Thanks everyone for the input on this issue.

That does not fix your leak, you just can't see now, because it's on the inside.

[MaxwellD]

Originally Posted by Kyle and Lisa;1285644 that does [ATTACH

16256[/ATTACH]not fix your leak, you just can't see now, because it's on the inside.

You are correct Sir!. After a few days, same issue occurred. I pulled the black tank flush inlet and discovered there was no check valve in there at all - so as the tank filled partially to the level of the flush nozzle, fluid simply flowed towards the inlet and leaked out under the cover cap in the convenience center.
I have replaced it with one that has a functional check valve. So far, so good.

[twindman]

Also, you mentioned the grey tank valve is left open. It should be closed a day or so before dumping, so you can use it to clean out the pipes after dumping.

[MaxwellD]

Yes - I do that when camping. This one is being lived in full time so I might ask the resident to do that periodically to exercise the dump valves and flush out any residue hanging around. Thanks!

[Carl n Susan]

Originally Posted by MaxwellD

You are correct Sir!. After a few days, same issue occurred. I pulled the black tank flush inlet and discovered there was no check valve in there at all - so as the tank filled partially to the level of the flush nozzle, fluid simply flowed towards the inlet and leaked out under the cover cap in the convenience center.
I have replaced it with one that has a functional check valve. So far, so good.

There was no check valve in the black tank flush connector as there is no need for one there (assuming you haven't modified the flush line system from what it was when constructed). The black tank flush line comes from the tank up to the anti-siphon valve (the back flow prevention device) under the bathroom sink and then down to the connector in the convenience center wall.

The black tank is located below the drop frame. The anti-siphon valve is above the height of the toilet. Black tank liquid would have to flow up around 5.5' before it could run down to the inlet connector and then *ONLY* if the anti-siphon valve has failed. There would be other significant signs of this should it happen.

It is highly unlikely the leak was from the black tank. As it has now stopped, it more likely it was a cracked valve which the replacement corrected.

[MaxwellD]

I thought my explanation waas too simple - so if I am getting backflow at this level, the anti-siphon valve may be faulty? I haven't located that yet but will keep looking. In the meantime I am just going to keep the black tank open for the time being. I will provide an update soon. Thanks Carl!

[Carl n Susan]

Keeping the black tank valve open is *NOT* a good idea. The liquids drain right out and the solids build up in a pyramid that hardens and is a PIA to get rid of. Keep the valve closed and see if the problem returns.

[MaxwellD]

ok will try that - is there a risk of septic liquids coming up through a failed anti-siphon valve if it has failed? That's all I am trying to prevent till I can locate that thing.

[Carl n Susan]

It is stationery so there is no chance you can fill the tank to overflow up through the flush line even if you don't dump. You would have sewage coming up in the toilet first.