smelly sewer problems while traveling

[cherylmccumb]

we have a washing machine closet on our rv. instead of putting a wahing machine i put a small freezer. when our black water tank is full and we are driving the rv we smell a strong sewer odor. it is so bad we have to open the windows while driving. the washing machine hookup is capped off. and we have stuffed something in the hole around the pipes. none of these things help. what can we do next. we do not smell the odor until we are moving.

[ArmyEOD]

Welcome to the site. Not sure how you have the drain line for the washer capped, but if it is just a small push in cap it will still leak/stink around it. If you can, pull the cap and pour a couple bottles of water down the drain. The water has evaporated from the trap. Hope this works for you, It did on my rig. Good luck and keep us posted.

[IMDSailor]

You mentioned that the pipe is capped, but is it sealed? Wrap some electrical tape or some such type, around it to seal it.
If this only happens while full and travelling it could be that the motion of the liquid in the Black Tank is covering the actual vent pipe, or it's full enough that the vent pipe opening is covered anyway. The sewer gas still needs to get out and if the Ex laundry drain is only capped but not sealed that's where it may be coming out. The laundry drain should have a trap at the bottom, which if still being used would have had water sitting in it to act as a seal. You don't use it anymore so the trap is dry allowing gas to come up the drain pipe.

Hope that helped.

[Mike Canter]

When driving do you have a roof vent open that is close to the black tank roof vent. The air is pretty turblent up there and sometimes instead of suck air out the vent bring the air in.

[Dogpatch]

It will almost always be a P-trap issue. If you aren't using the washer stand pipe, you are better to cap it. Use a proper ABS 1-1/2 cap. They are typically orange in color and can be purchased at any hardware store. They fit snug when installed.

In addition, you will need to ensure all the remaining sinks have water in the p-trap. Depending on the roads you are traveling and the rocking of the RV, it will empty the P-trap enough to allow gas to come from the tank. You may have to add water to drains more often in this case. Don't forget about the shower drain as well.

[DKY]

Dosen't the washer water dump in the gray water tank ? It could be the toilet seals too.I had oder going down the highway and put on a Cyclone stack vent,took care of the problem.

[Mike Canter]

Sometimes the gray water smells pretty bad also BUT never as bad as the black but they both use the same vent on the roof

[njs42]

Originally Posted by Mike Canter

Sometimes the gray water smells pretty bad also BUT never as bad as the black but they both use the same vent on the roof

A small distinction I know, but some MH's (mine) have seperate vents through the roof for black and grey tanks.

The problem however is almost always the P-traps, vents, or the venturi effect on the roof drawing odors from whatever source black or grey back into the coach.

One universal truth; it stinks.

[daveshan]

You probably have one of these somewhere close to the P-trap


It's labeled "check vent" in this picture but it's also called a "cheater vent" all they are is a vacuum break that allows the P-trap to function properly. They get old and allow stink up into the living area. They're ~$2-3 at Home Depot, I had to replace all 3 in our coach before we could travel with the roof vents open and still breathe.

Ideally all traps should be vented up through the roof just like in your house but due to space and $$ concerns lots of coaches seem to have these instead.

[distaff]

There can be a number of causes, many of them already mentioned. You don't say what kind of coach you have, but in my Monaco there is a sort of stack coming off the drain below the p-trap in one of the bath room sinks. The cap can be knocked off, and if it is, it will leak tank fumes into the coach.

I also got rid of the normal stack on the roof and replaced it with a directional stack with a wind vane (turns to point down wind).

Last, if I have my front windows open and I'm driving, I sometimes find that the p-trap in the shower loses its water seal (water in the trap prevents gasses from coming up), and I have to pour some water into it to make it stop stinking. Try putting a couple of cups of water in all your traps.

[Dogpatch]

Originally Posted by DKY

Dosen't the washer water dump in the gray water tank ? It could be the toilet seals too.I had oder going down the highway and put on a Cyclone stack vent,took care of the problem.

The gray tank can smell every bit as bad as the black due to the food stuffs that can accumulate in the tank. Every bit of care in rinsing and deodorizing the gray water tank should be given just as the black.

[Sundancer268]

This is what I used and I love it. No moving parts to wear out and low profile to reduce the chance of a tree branch causing a problem.
360 Products Universal Holding Tank Roof Vent Siphon Cap

[bjsheldon]

The "Cyclone" tank vent available at Camping World for $20 will also do the job. I had the same problem, added the Cyclone and walla, no stink.

[toneumanns]

Originally Posted by bjsheldon

The "Cyclone" tank vent available at Camping World for $20 will also do the job. I had the same problem, added the Cyclone and walla, no stink.

This worked well for us also. No odors since installing.