5th wheel sewer smell

[Brankon]

I got an old 1998 21.5' 5th wheel trailer last year that needed a little bit of work, so I did all of that and I replaced the water valve in the toilet because of a leak, new one leaks too so I have to do that again this spring. When I replaced the rubber o-ring between the toilet and tank I didn't use any Vaseline or anything on it, it went on dry and i put the toilet back. did my best to flush out the black tank (bought a clear adaptor to make sure water was coming out as clear as I put it in when flushing it) but I still continue to get a sewer smell inside the trailer. The new water valve i got for warranty came with another toilet o ring, so I'm wondering if I was supposed to use Vaseline or something on the ring? Want to do this right this time and hopefully get rid of the smell.

My other idea is that the vent stack might be plugged up on the roof, might end up trying to stick a plumbing snake down it and verify that it is not blocked.

Any other suggestions I could try and can someone verify if I need to put something on the o ring under the toilet or just put it on dry?

Going to try and clean the hollow part of the toilet better than I did last time too. (God rv toilets get really gross inside there!)

Long winded post but its better than flooding the discussion with questions. And finally any suggestions on cheaper toilet chemical for trailers would be sweet too! Wondering if the smell may also be chemical quality related

Sent from my SM-G965W using Tapatalk

[geezer55]

We had a sewer smell in our trailer and it was the air admittance valve the stopped working, changed it out and no more smell. Ours was located by the kitchen sink.

[bat119]

Make sure there's water in the p traps, in a seldom used shower the water will evaporate allowing sewer smell to back up.

[big zeke]

Originally Posted by bat119

Make sure there's water in the p traps, in a seldom used shower the water will evaporate allowing sewer smell to back up.

I think most sink and tub drains flow to the grey water tank, the toilet is the only thing going to the black tank. There should be a tank stack vent on the top of the trailer that vents out all black tank vapours...the cover on this vent sometimes gets pounded shut (broken) by hail and this can stop the tank from venting and may cause the odors inside the trailer. Also check to make sure the seal on the toilet valve is in good shape, it seals the black tank from the washroom. These seals can dry out so it's a good idea to leave some tank chem on top of the toilet valve (just dump some on it when the valve is closed)

Typically the black tank should be empty when not in use, bad idea to leave it full between trips.

[bat119]

The grey tank smell can be just as bad as the black' sometimes mistaken for the sewer smell.

Zeke is right only outlet for the black is your stack

[Tungsten,]

One of those mirrors or your neighbours HD video cam and look in from the toilet see if theres some stuck to the walls.If thats clear then its just a matter of rinsing with chemical.

[Dewey Cox]

Any chance it's gas?

[JULIUS]

I had a terrible odor in my rv a couple of years ago and it was like sour eggs. Turned out to be from my hot water tank and not my sewer. Flushed it with vinegar a few times and no more problem.But this was when I tried to use the water of course so it might not be related.
Good luck

[javlin101]

You would not believe how much a dead mouse can stink up a place.

[BUSHRVN]

Originally Posted by geezer55

We had a sewer smell in our trailer and it was the air admittance valve the stopped working, changed it out and no more smell. Ours was located by the kitchen sink.

THIS. Mine has two, one under the bathroom sink and one under the kitchen sink, so check for more than one. As already mentioned, grey can smell just as bad. I have had the same problem after towing for a few hours, it would reak when you opened the door!!!
If you’ve got crud built up on the walls of your black tank, on your next warm weather trip dump about 3 or 4 bags of crushed ice down the toilet and have the tank about 1/3 to 1/2 full of fresh water and tow it around for a while, this will break up any solids and make for a nice chocolate pudding when you dump.
I typically do this once or twice a season on the way home just to give it a nice thorough cleaning.
I’ve gotta replace the two vents in the spring because I’m sure they are the culprits to my stench problem too. I taped them up on the last trip.

[bat119]

How we discovered the grey water stank
If we didn't use our seasonal for a couple weeks the P traps would dry out when water was put down the kitchen sink gas from the grey tank was forced through the shower drain stinking up the bathroom.
I changed the toilet before a buddy clued me into leaving the plug in the shower drain when it's not used.

[Brankon]

These are all great ideas of things to check! Thanks guys!

Now can anyone confirm if I need to coat the rubber o ring between the toilet and black tank with anything or does it just go on dry? I need to pull the toilet to do the water valve anyways so I want to do it right this time

[bat119]

Originally Posted by Brankon

These are all great ideas of things to check! Thanks guys!

Now can anyone confirm if I need to coat the rubber o ring between the toilet and black tank with anything or does it just go on dry? I need to pull the toilet to do the water valve anyways so I want to do it right this time

dry the foam ring is the seal
I put a red plastic cup in the black tank hole while working to keep the odour down.

good luck!

[walker1]

Is it possible you have another tank that you were unaware of? A stretch but I know of a few have encountered this as there was a hidden draw handle between their tires they were not aware of. It was grey but still stunk the joint up!!!
Good luck.

[Steve W]

As part of my regular maintenance I put a cap/lid full of laundry soap and a cap full of water softener in both my tanks after I empty them. I add a couple of gallons of water right away. More if I’m not going to use the unit for awhile. The water softener keeps the tank wall slick and the detergent helps keep things clean and breaks up grease etc. Google the GEO Method. It’s where I got the idea.

Good luck with your repairs.

[kevinhits]

Originally Posted by geezer55

We had a sewer smell in our trailer and it was the air admittance valve the stopped working, changed it out and no more smell. Ours was located by the kitchen sink.

x2...I had the same issue and replaced the same valve under the kitchen sink. No issues after that.

[baxter]

I had the same problem and it turned out to be the fresh water tank. An RV tech told me that after he installed a new toilet. I flushed the tank with bleach 2 times and the smell was gone. The trailer was on the driveway so it was easy to drain the tank. If all else fails for you may want to try this. Good luck.

[Jack Hardin]

I had a sour egg smell from the kitchen sink in a previous trailer and I put holding tank cleaner down the drain and it cleared it up. Same stuff you put in the toilet.

[koothunter]

What kind of toilet? I had a bad stink and tried a few suggestions from RV places to remedy the problem with no luck. They all claimed it can't be the toilet. I changed the toilet to a porcelain RV toilet, and smell was gone immediately. The original was a crappy Thetford plastic one with the hand flush.

[Rangerdude]

We had a similar issue in our RV as well. Tried everything. Thought the sewer vent was plugged, it wasn't. Thought the black tank wasn't completely cleaned out/empty. Flushed multiple times with wand down the toilet and multiple times with black tank flush. Didn't help. Eventually took the toilet off thinking inaccessible parts of the assembly needed to be cleaned. When I took the toilet off, I noticed the smell was coming from the seal/flange between the toilet and the RV floor. Threw it out and replaced, smell was gone.

[no-regard]

Originally Posted by JULIUS

I had a terrible odor in my rv a couple of years ago and it was like sour eggs. Turned out to be from my hot water tank and not my sewer. Flushed it with vinegar a few times and no more problem.But this was when I tried to use the water of course so it might not be related.
Good luck

My wife and I borrowed her parents 5th wheel a few years ago, got all set up, having a good time. The next morning when any tap was turned on, the absolute rank smell coming from the water (fresh) could raise the dead. Not sure what happened, but it was found later to be from the hot water tank. Father in law flushed it out and all was well afterwards.

Every time we borrow that unit something bad happens; big rock in windshield, blew a tire, batteries dead...

[brewster29]

Originally Posted by bat119

How we discovered the grey water stank
If we didn't use our seasonal for a couple weeks the P traps would dry out when water was put down the kitchen sink gas from the grey tank was forced through the shower drain stinking up the bathroom.
I changed the toilet before a buddy clued me into leaving the plug in the shower drain when it's not used.

This was my experience too. I struggled to find the source of sewer smell in my trailer bathroom last year. It was coming from the tub trap/ grey water tank. Found it when I placed a cup of the blue stench control down the tub drain. Although I had drained the grey tank, enough water had sloshed out of the trap on the way home to allow stink from the grey water tank to enter my bathroom.

[Brankon]

Originally Posted by brewster29

This was my experience too. I struggled to find the source of sewer smell in my trailer bathroom last year. It was coming from the tub trap/ grey water tank. Found it when I placed a cup of the blue stench control down the tub drain. Although I had drained the grey tank, enough water had sloshed out of the trap on the way home to allow stink from the grey water tank to enter my bathroom.

I may have to look into that. The tub never gets used, gotta say the last time it had water in it was when I deep cleaned the entire trailer after I got all the work done! Might be a good idea to dump something that doesn't evaporate down the tub drain and hope that helps too

[HunterDave]

Air the trailer out and do sniff tests to find the source of the leak. I had this happen in my trailer and I found the source by sniffing the drains. One P trap had dried out and it was easy to find. If you don’t find the source there, pour some water (you didn’t winterize with RV antifreeze?) down the drains. Continue sniffing until you find the source.

One time I had a rotten egg smell and it was coming from my battery that was giving off gas.

You should be able to find the source using your nose imo.

[tbiddy]

We’ve had a few unpleasant smells from various RV’s we’ve owned. I’ve had the bad battery give off the rotten egg smell in our small travel trailer. In our fifth wheel, we had a terrible smell coming from around the sink. It turned out we had a small propane leak at the stove. I worked with a propane company for a few years and it wasn’t the typical mercaptan smell and wasn’t enough to set off the gas alarms either. And in our motorhome, if I’m driving with the windows down, I get a rotten egg smell. I find if I pour water down all the P-traps (or roll up the windows) the smell goes away. Must cause some kind of vacuum that pulls the gas out of the grey tank. And if you get a rotten egg smell from the taps, I’ve found if you use untreated well water and don’t drain the hot water tank after camping it will cause the smell. Found that when we stayed at a friends lake lot at Buffalo Lake and filled the motorhome with their well water. Had to flush the tank with water when we got home and the smell went away.

[Brankon]

Originally Posted by HunterDave

Air the trailer out and do sniff tests to find the source of the leak. I had this happen in my trailer and I found the source by sniffing the drains. One P trap had dried out and it was easy to find. If you don’t find the source there, pour some water (you didn’t winterize with RV antifreeze?) down the drains. Continue sniffing until you find the source.

One time I had a rotten egg smell and it was coming from my battery that was giving off gas.

You should be able to find the source using your nose imo.

come to think of it I did winterize with antifreeze, so the smell really has to be coming from the toilet because all 3 other p traps will still be full of the antifreeze, I do get the rotten egg smell too but I know for sure that I need to run some cleaner or something through the hot water tank, it even stinks if I drain it and leave it open for some reason.

My next steps are going to be pulling the toilet and doing the water valve again and putting the new foam ring on and then I'll get a ladder up on the roof and see if I can shove something down the black and gray tank stacks to verify that they aren't plugged up with gunk sewer smell is the worst