URGENT HELP NEEDED - MAJOR SMELL FROM BATHROOM

There may be an air admittance valve under the sink, if you can find it, seal it with a plastic bag.

Don't run roof vents. Your best approach at this point is to push air into the trailer for positive pressure. Open a window facing the wind and close all other windows.

Great, smell is gone now.

Thanks all for your precious input.

Now 1:20 a.m... will go to bed and tomorrow will check the valves under bathroom cabinet.

Cheers!

Marc

The one time we had this problem it was due to the black tank vent being partially blocked. To check that the vent is open you have to get on the roof of the trailer, remove the vent cover and look down the vent tube with a flashing. You should be able to see into the black tank. Another issue could be the vent cover has shifted and is blocking the vent. I cut about 1/4 - 1/2 inch from the top of the vent to provide more space for fumes from the tank to escape and that solved the problem. If that vent is blocked gas pressure builds up in the black tank and when you flush the toilet the pressure and fumes get released into the trailer.

The Tank Dump Valve has to be fully closed, even on a Full Hookup site.

marcarolle wrote:
I always use Camco orange RV black tank concentrated treatment after emptying both tanks. We started our stay on empty tanks.

The only time the grey / black tanks should be completely empty is when you winterize, otherwise never. Once you've dumped & flushed either you want to add a minimum 10% capacity of the tank with fresh water and tank chem of your preference which you'll then start your next camping trip with.

We had a similar situation last winter. Tried everything and finally opened up the basement area and discovered a vent pipe had unglued under the bathroom. Of course, it was so far in the crazy arrangement of wires, pipes, and equipment that it took a bit of meneuvering to fix. Solved the problem.

Do be aware that a major component of “that smell” is hydrogen sulfide, which is a nerve toxin and decreases your sense of smell. Thus a decrease in the smell may not correspond with any actual decrease in the presence of sewer gas.

Your black water tank only has a few exits for gases.

First is through the toilet itself. If your toilet valve is holding water in the bowl (and there is always some residual water after you flush), then the valve is water-tight and thus gas-tight and no vapors are coming up through the toilet.

Second is through the P traps of your bathroom sink. I have heard that in some RVs some sinks dump into the black tank, even though it is technically "grey" waste water. Those P traps are designed like they are to hold water in them, which block the flow of gases through the trap. If you haven't use your sink in a while, the water in the P trap can evaporate out, leaving an open passage from your dump tank out through the sink drain hole. I have heard it said that this water in the P traps can also slosh out of the trap from driving the RV/trailer. The fix is run a little water through your sinks when you get where you are going.

Third is your vent stack. Your tanks are vented through PVC pipe going up through the roof. If the vent pipe becomes disconnected or broken inside the RV, then your tank will be venting into the RV. Likewise if you have a vent or window open near where the vent exits the roof, then it is possible to suck vent gasses back into the RV.

Steve

Grey tank can stink just as bad as the black. If you never use your tub/shower the trap can go dry and allow fumes into the living space. Pour some water in your traps.