Bathroom stench after flush and chemicals

[kyonu]

I'm sure this has been a topic many and far, but I have to ask again as many of the issues I've seen regarding this weren't completely answered. But...

With my recent purchase of my new Class C RV, the previous owner left a holding "pyramid" (to put it lightly) that we could smell every so often when using the bathroom (primarily when we flushed, letting up all the stench).

Well, I did a thorough flush, which involved a high-powered nozzle on the hose, through the open window, directly into the toilet (since we don't have a dedicated flush valve). After about an hour of filling the tank and flushing it out, blasting etc, the water finally came out clear!

As an added bonus, the holding tank meter always showed "2/3 full", and after the deep flush it was showing empty, meaning we got out a lot of what was in there.

I added chemicals per instruction (1 bottle of chemicals = 40g tank cleaning), with water as per instruction as well. (it is a 40g tank)

That night, the same stench from before returned like a phantom. It was horrible, but we had not used the bathroom since we flushed it and chemicalized it. The tank still showed empty.

Any earthly idea as to why it would still be stinking? It comes and goes, so I know it's not burned into the walls. We open the vent, close the door (toilet is sealed off with it's own door and room) and after 5 minutes it doesn't smell anymore. an hour later, a stink bomb comes back and we repeat step 1.

ANY ideas whats going on? Tips, suggestions? I am knew at this but willing to try anything. I scouted the bathroom, took out the toilet and wall fixtures and there doesn't seem to be any issues. The stink comes in regardless if we're flushing the toilet (yes, there is about an inch or two of water in the toilet as a "stink barrier" per recommendations I looked at before.)

Please help! (and thanks!)

[Old-Biscuit]

Does the toilet hold water in bowl?

If not toilet bowl seal is leaking......it should hold water to provide a 'vapor barrier' because rv toilets don't have built in 'p' traps like residential toilets do.

Dry bowl.......black tank smells can come inside via toilet.

Clean seal & ball valve really clean top/sides/bottom) using your hand and soapy water. This means having toilet valve open while you clean seal/ball valve
so turn rig water supply off until done.
Then after thoroughly clean--rinse and pat dry then using your hands coat seal completely with olive oil to make it flexible.

Then turn on water supply and puts some water in toilet bowl.
It should hold water.....if it leaks out----replace seal.

No water in bowl----you will always smell black tank

[old_guy]

two words, HAPPY CAMPER. you can buy it on the internet, great stuff. will take care of your problem. I have used every tank additive on the market and even some made up to fight the smells. you can even use it in your grey tanks to combat the smells. one thought about cleaning the tank, did you also clean out the shaft leading to the tank? there are places in some that will stop poo and will smell like crazy too.

[wa8yxm]

Are you sure the stench is from the black tank?
Under the sink should be an air admittance valve (A type of vacuum breaker) for the gray tank,, IF that fails it can let Gray tank Stench back into the room.

Finally, Try it without the chemicals.. They truly do nothing but flatten your wallet.

[jplante4]

kyonu wrote:
Thanks everyone for your quick responses! I will definitely check the AAV under the bathroom sink.

The smell only occurs in this space. It's worse with the lid open, and we typically will not smell it unless we open the door (as shown in the pic). If it's NOT the AAV, how should I go about cleaning the vent pipe?

Thanks again!

Climb up on the roof with a running water hose and stick it down the vent. If it's plugged, it will fill up and overflow. Jam the hose in as far as it will go, jiggle is around and when the vent drains you're done.

Yeah, you can do it with a snake, but this is much more fun. And you already have a hose, probably not a snake.

[kyonu]

Thanks everyone for your quick responses! I will definitely check the AAV under the bathroom sink.

Now, what has me curious, is this. Here is a picture of my bathroom (sorry about the size if it's too big!) :



(don't mind the debris, it has since been cleaned)


The smell only occurs in this space. It's worse with the lid open, and we typically will not smell it unless we open the door (as shown in the pic). If it's NOT the AAV, how should I go about cleaning the vent pipe?

Thanks again!

[Bumpyroad]

anyone with a "pyramid" and no black tank flush device, I would recommend buying the device, drill the large hole in the wall opposite the drain, if accessible, poke a pressure washer wand into the hole and blast away. then install new fitting when done.
you want the device anyway and can beg, borrow, or rent a washer.
bumpy

[C-Bears]

Another thing we do every few months, I close both gray tanks and pour in an additive for gray tanks. We let them stay closed for a couple of days and then dump them. I have a Flush King mounted on my sewer pipe and I then use it to back flush both gray tanks, one at a time.

No matter how careful you are there are still food particles and junk that get down inside your gray tanks and just sits there.

[copeland343]

We had a smell problem in the bathroom also. It was the toilet were the two half's are joined together. I called Thetford and they sent me a new toilet under warranty. It was a easy fix but took me a few days to find that is were the problem was. Look behind the toilet there is a open area about bowl high off the floor, look in there or take picture with phone found liquid in that area. Just somewhere else to look I thought I had tank problems also but it was the toilet.

[lanerd]

Yes....the AAV is probably your problem. There may be one under both the kitchen sink and the bathroom sink. Replace both.

good luck

Ron

[gotsmart]

The OP may need to deodorize the tank with bleach and let it soak 6+ hours, then dump and rinse the tank with plain water.

[Old-Biscuit]

As indicated my previous posters...Air Admittance Valve under sink.

If previous owner left you a poop pyramid they probably didn't take care of grey tank either.
This is one of the reasons I don't like leaving grey tank drain valves open when hooked up. All the liquids flow away and all the stuff (body funk, hair, scum etc.) gets left behind--dries out and starts decaying.
Then when the Air Admittance Valve fails........stink comes inside and grey funk is as nasty if not more so than black tank.

Air Admittance Valves are used to prevent 'P' traps from getting sucked dry when draining grey tanks.

[IAMICHABOD]

The smell may not be coming from your Black tank,it may be the gray tank. As mine was.


I would check and replace the air admittance valves
located near your sinks,they are cheap and can be found at most big box stores like Home Depot and Lowes as well as smaller hardware stores.

If they fail they will let the smell from the grey tanks in and believe me they can smell just as bad as the black tank if not worse.


Changed mine out and the smell was gone!

[TucsonJim]

Here's another path to go down, because it happened to me. It wasn't the toilet at all, but the stink was coming from the bathroom sink. Underneath our bathroom sink, there is not a vent that goes directly to the roof. But there is an "air admittance valve" which is a perfectly fine way to vent the plumbing. But our air admittance valve failed, and it was letting tank gasses come into the bathroom at all times. I could have sworn that smell was coming from the toilet, and accused my son of covertly eating pickled eggs and cabbage.

If it is the air admittance valve on your sink, it's very easy to fix. Just unscrew it, and buy another one from Lowes or Home Depot for about $20 and replace it.

[ford_truck_guy]

I too would check for a blocked vent pipe..

[kyonu]

Harvard wrote:
Always ensure the house has either a neutral pressure OR a positive pressure to out doors before flushing the loo. In other words, if you have either a kitchen fan or a fantastic fan sucking air from inside to outside when you flush the loo this type of problem happens.

And/or if it is a windy day and a downwind door or window is open, presto! etc etc

I made sure of this as well. Fan's off and (it being winter, super cold in northwest Texas, etc) the house is completely closed up. The stench also appears when not flushing as well.

How would one check a blocked vent? Do we need to put water down the pipe or something? (which also tells me... I need to find where the vent is!)