Help identify source of bad smell

We always insert a rubber stopper in our shower drain and all sink drains when in transit for this very reason. The p-trap filled with water can be over taxed if there is enough dynamic pressure force at highway speeds. Some people have had success with vent vanes which insures a suction from holding tanks which depend on wind/air movement over vents.

Back in July when you had this problem you said the odor went away as soon as you dumped. How long has it been since you dumped the tanks this time ?
Are you using any chemicals in your tank ?

Aaahhh. Drove the unit from Michigan to Florida. Smell's still there when we flush. No smell in the bathroom itself; just the bedroom when we flush. Very, very frustrated.
DH wants me to add that the person who worked on the problem said there chunks of building materials, making it so the valve remained open. He cleaned it out and replaced the cap under the bathroom sink. Could there still be some debris causing problems.
Wondering if we got a bad unit...

We were having problems with black tank odors on our last outing. It turned out we had a large paper wasp nest blocking off most of the vent on the roof.

The black tank system is pretty simple, the toilet is the only thing connected on the input side, the drain is on the other side, and the vent pipe connects to the top of the tank and runs up to the roof. Make sure you leave some water in the toilet bowl to form a seal, check the roof vent for an obstruction. If the drain valve is failing you're going to have sewer running out on the ground.

Finally took the unit to the shop. It was the vent caps inside the bathroom. Easy fix.

I have not read anything here about the role the BEDROOM VENT might play. If the bedroom vent were open and downwind from the Black Tank Vent, you get the picture.

That black tank is good for 7 days if you put in chemicals or a week with nothing more than water. After that time frame...yer gonna get stink.

Throw all the money you want at vents and caps...it's still going to smell if'n you don't clean it out once a week.

Start out with 5-8 gallons of water in the tank, too, eh.


Gary Haupt

We're home now. Thanks for all the suggestions.
Odor went away as soon as we dumped. So, since unit is new will try together replacement caps/vents under warranty sand try not to go 10 days between, we'll, dumps. ;)

It appears your bedroom and toilet share a common wall. It looks to me like you are going to have to crawl under the unit and physically check the pipes and the upper section of holding tank for breaks.

reinita wrote:

Found the pipe piece thanks to gboop's link. I took it off and put it back on. Can't tell if there's anything wrong with it but p-ew, it certainly reproduced the bedroom smell in the bathroom.
Anything else?

There may be another one under the kitchen sink. This is where mine went bad. When I took mine off, it wasn't possible to tell if it was bad or not...I just replaced it and it took care of the odor. If this is the problem, the odor is coming from your gray tank. I now treat my grey holding tank with the same chemical as in my black tank. I just buy store brand treatments. You could try to get some grey tank or black tank deodorizer down your drains and into the tank and see if that helps. I would change out any of these valves...around $5 at hardware stores.(bring a sample along to the store) If that does not solve the problem, you will know the old valves were good and save as spares.