Sewer smell when dumping

Xer

Member
HELP. Lately when I dump the black water the sewer smell come into the rv. It seems to come from the shower drain. When I dump the black water tank both grey water tank valves are closed. We do not smell the black tank while we are camping only when we dump. Ant ideas on how to fix this would be greatly appreciated

2013 landmark San Antonio
 

carl.swoyer

Well-known member
Look under the sinks for a studor valve. One has probably failed.
Not expensive. Easy fix
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Lou_and_Bette

Well-known member
You can check the Studor valve by placing a plastic bag over it and sealing tightly...if smell goes away, problem solved. I had another problem with smells only when dumping, and I have seen others who had the same problem, and the source was a significant gap between the vent pipe and the roof. To check this, remove the vent flange on the roof and seal the gap between the wood and the pipe. My smell went away. I have seen others whose vent pipe was too short and didn’t clear the roof.
 

carl.swoyer

Well-known member
You can check the Studor valve by placing a plastic bag over it and sealing tightly...if smell goes away, problem solved. I had another problem with smells only when dumping, and I have seen others who had the same problem, and the source was a significant gap between the vent pipe and the roof. To check this, remove the vent flange on the roof and seal the gap between the wood and the pipe. My smell went away. I have seen others whose vent pipe was too short and didn’t clear the roof.
Covering the studor valve will probably be effective, but I'm thinking it would slow the dump process as the valve allows air movement.

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danemayer

Well-known member
A baggie over the Studor valve is a good test and a temporary workaround. Drains need to be vented, so if you find that the Studor valve is stuck open, allowing vapors into the trailer, you'll want to replace it.
 

Flick

Well-known member
HELP. Lately when I dump the black water the sewer smell come into the rv. It seems to come from the shower drain. When I dump the black water tank both grey water tank valves are closed. We do not smell the black tank while we are camping only when we dump. Ant ideas on how to fix this would be greatly appreciated

2013 landmark San Antonio

This is what I believe. Referring back to your original post, I think that the studor valve is not the problem. Since the studor valve is venting the sink which in turn is in line with the grey tank, a malfunction of this valve shouldn’t cause the odor, especially when you only notice the problem when you’re dumping the black tank.
I think something may have moved or shifted creating an air leak from the outside into the udc into a space around a pipe, etc. that is allowing outside smells to get into the coach, like for example, an open window would do. Just a thought.
 
I have a new Cyclone 4006 and the shower drain has no p-trap. Shouldn't affect black water though, and that tank only gets shower and bathroom sink water which normally doesn't smell bad.
 

Gary521

Well-known member
I have a new Cyclone 4006 and the shower drain has no p-trap. Shouldn't affect black water though, and that tank only gets shower and bathroom sink water which normally doesn't smell bad.
Soon you will find out that the grey water smells just about as bad as the black water. There is all kind of things that get into the grey water and decompose ( food particles, skin oils, dead cells etc ). I am pretty sure that you have a "p" trap somewhere. If no P trap, then you have a Hepvo valve.
 
Soon you will find out that the grey water smells just about as bad as the black water. There is all kind of things that get into the grey water and decompose ( food particles, skin oils, dead cells etc ). I am pretty sure that you have a "p" trap somewhere. If no P trap, then you have a Hepvo valve.

Nope, the shower drain goes directly to the roof vent pipe. And it leaks right under the shower. So I'm trying to figure out how to put in a ptrap. It's in an awkward location and I may have to use the Hepvo valve. Do those work well?

I've been hoping that the grey tank won't stink as much because the kitchen sink doesn't go to it. But yeah, we treat the grey tank too.
 

SNOKING

Well-known member
Some trailers for the bathroom sink connected to the black water tank. Our 29' Cardinal was that way. You could see the smaller sink line Y'd together to the toilet line in the basement. Chris
 

Xer

Member
Thanks for everyone’s help. What I found was the vacuum Breaker valve was where the smell was coming from. I have a a removal panel behind the bedroom door for the shower valve. If you look into the wall you can see the Breaker valve. What surprise me was it was not leaking water but when I connected the tank flush hose and turn it on the smell was definitely coming for there. I was going to replace it with a brass valve but local Lowes and Home Depot did not have one so I went back with the plastic one which I was able to get from the local RV store
 

Flick

Well-known member
Thanks for everyone’s help. What I found was the vacuum Breaker valve was where the smell was coming from. I have a a removal panel behind the bedroom door for the shower valve. If you look into the wall you can see the Breaker valve. What surprise me was it was not leaking water but when I connected the tank flush hose and turn it on the smell was definitely coming for there. I was going to replace it with a brass valve but local Lowes and Home Depot did not have one so I went back with the plastic one which I was able to get from the local RV store

Thanks for the update.
 
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