bathroom smells while travelling

There is no aav, I'm a seasoned rv owner, and have looked, the only thing I've not done is checked the vent, which I will do soon.

36guy wrote:
Well, was under the sink, there is no valve there, just the standard setup a residential sink has, a p trap, and nothing else.
It's not the shower, the bathroom is separate, the shower is in the hall and does not smell.
I'm gonna try the next trip by putting the plug in the sink, trying to determine exactly where the odor is coming from. Roof vent is closed, toilet holds water, that only leaves the sink.

I had the seal between the toilet and the black tank flange go bad once. I had to take the toilet up and replace the seal.

I also had the black tank roof vent get stopped up once. It caused the AAV under the bathroom sink to rupture every time I emptied the black tank. I would replace the AAV and the smell would go away until I dumped, then would return. After replacing the AAV a few times, I unclogged the roof vent. Then, when I replaced the AAV I had no more problems.

And, all sink drains HAVE to have a vent of some kind between the sink trap and the tank. Otherwise the vacuum would ALWAYS pull the water out of the trap. Look under the sink again. If you don't have an AAV under there after the trap, it has to be vented through the roof after the trap.

An AAV will be on a PVC stub sticking up above the drain pipe that just ends.

Here is an image off of Google

bartlettj wrote:
Also check your air admittance valves. There will be one under each sink, screwed into the ABS sewer piping.

Yup. A bad valve can cause unwelcome smells inside the coach when traveling.

Well, was under the sink, there is no valve there, just the standard setup a residential sink has, a p trap, and nothing else.
It's not the shower, the bathroom is separate, the shower is in the hall and does not smell.
I'm gonna try the next trip by putting the plug in the sink, trying to determine exactly where the odor is coming from. Roof vent is closed, toilet holds water, that only leaves the sink.

rdhetrick wrote:

Sorry you are wrong. In

'most'

RV's the bathroom sink does drain into the black. OP has a Class C MH, his sink empties into the black. ......

Wow, what an insanely arrogant,

yet totally incorrect statement.

I had a class C, without a doubt, my bathroom sink emptied into the grey tank.

Some do, some don't.

You contradict yourself. Bash me for an incorrect statement and then make the same statement.:?


And Yup, and that is pretty much what I said....."MOST" DO. :R

Me again, I have maxair vent covers, but the smell isn't coming from the roof, the bathroom vent cover is closed when travelling, the smell is faintly noticeable from the driver seat while moving, but after you stop, opening the bathroom door will knock you over.
The toilet retains water, it's not coming from there, I haven't had time to crawl under the bathroom sink yet, but seems to me that may be the problem.
I have owned my current fifth, (for sale), for twelve years, never had an issue like this, decided to try a class c motorhome, and immediately encountered this problem, no smell while parked and in use, but a killer when travelling. Funny enough, previous owner was a plumber.

I had a trailer that the black tank vent was in front of one of the roof vents. I had a Maxair cover on the roof vent and traveled with it open. I learned to keep that roof vent closed.

Sorry you are wrong. In 'most' RV's the bathroom sink does drain into the black. OP has a Class C MH, his sink empties into the black. ......

Wow, what an insanely arrogant, yet totally incorrect statement. I had a class C, without a doubt, my bathroom sink emptied into the grey tank. Some do, some don't.

Put the stoppers in the sink and tub when moving,all it took to fix ours.

gafidler wrote:
the sink in the bathroom does not drain into the black tank, it goes into thr gray tank.

Sorry you are wrong. In 'most' RV's the bathroom sink does drain into the black. OP has a Class C MH, his sink empties into the black. Those with 5'ers usually have an extra gray(galley)tank may not.

All you have to do is drain your black tank and leave it open and run the water in the bathroom sink and see if it runs out. Many of you will be mildly surprised! :C

Which also is why so many ask why their black tank fills up so fast. Have a family of 4 on board washing up and brushing teeth in the sink everyday and that is why the black fills up so fast.

I travel solo and when I don't have hookups I don't use the bathroom sink and that alone extends my stay before having to dump by 2 days.

Smell in bathroom and everything is working right? Empty p-trap in bathroom sink.