bathroom smells while travelling

I own a fifth, never had this issue before, the toilet holds water, even while travelling, the smell is not there till the motorhome is moving. Could be the sink, I haven't checked yet, it's our first trip with it, I normally use a septic tank treatment, have for twenty years, it's biodegradable and cheap.
I also have always dumped five gallons of water back into the black tank after flushing, so except in the winter, it always has water and bacteria in it.

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

Before doing any type of major reconstructive surgery on your camper, I recommend you try two things first, one which has already been mentioned.

1) Empty your black tank, add about 10 gallon of water and a gallon of bleach. Go for a 15 minute drive then dump your tank. Rinse, and dump again.

2) With your toilet completely empty (turn your water pump off and press the peddle on the toilet), put a small amount of vegetable oil on the slide valve and slide it back and forth a few times to get it good and slippery. Work it a few times, then turn your water source back on again.

Although it may seem like the slide valve is shut, it's possible it's really not. They can stick open allowing smells from the tank to come up. The vegetable oil will not hurt the rubber seal, and it creates a lubricant, and act as a cleaner to soften any gunk that may be trapped in the rubber seal, where you cannot see it.

Chances are, the previous owner was one of those RVers who state they never had to clean their black tank. Well, now you know what happens when they don't get cleaned out every now and then.

A bit of bleach every now and then with a few gallons of water a couple times a year, going for a drive, and then dumping right away does a LOT to keep odors out of your tank. Once you get it clean out, simple water flushing will do it quite well also (after you get it clean out the first time). Then an occasional good dose of bleach and water will keep it that way.

Try it, before doing any surgery on your camper. You've got nothing to loose, and everything to gain. If this does not work, THEN consider one of the other suggestions listed above in previous posts.

I'm a believer in doing the least evasive, least costly attempts first, and eliminate simplicity before going complex.

FYI, run some bleach water down the Grey tank also. It won't hurt anything either.

old guy wrote:
my guess is the water in the pee trap is draining out as you drive and the grey tank smell is coming up through the sink.

X2

Also in hot weather if you don't use the bathroom sink often or you have left it parked for awhile between trips the water in the sink p-trap evaporates. Since it drains into black tank the sewer smell will come right up thru the sink drain.

I've had it happen quite a few times traveling in the south. I don't wash my hands in the bathroom sink because it makes the black tank fill up faster. Sooo the p-trap water evaporates all the time. :R

Just add water to the sink to fill p-trap.

We found that the bouncing on rough roads was letting all the water out of the toilet, so there was not anything to block black tank smells coming up through the toilet. Finally figured this out because after a particularly rough road there was water out in the middle of the floor.

Check your vent. Check the roof vent to make sure it's closed. If those are ok, the smell is probably coming up through the toilet. Not much to be done about it except add water and run the fan as soon as you stop.

Other possibility is that the air admittance valve under the sink is letting in gray tank odors, which can be pretty awful. This might be worse while driving due to sloshing around.

"There's not much you can do when you're actually moving besides dumping some bleach down your black tank." AND the sinks...more than once...3 times minimum. And the roof vent like Bumpy suggests.

There's not much you can do when you're actually moving besides dumping some bleach down your black tank.

my guess is the water in the pee trap is draining out as you drive and the grey tank smell is coming up through the sink.

Try this

It could be the bathroom ceiling vent is sucking air up through the toilet and tank when traveling... Make sure the crank open ceiling vent is closed and see what that does...

Roy Ken