Bad smell in bathroom 2022 Micro Minnie 2108FBS

[eatSleepWoof]

I've been struggling with this for a while. We don't have any bad smells while in camp, but when we dump the tanks on the way home and park the trailer at home, the trailer starts developing a bad smell, primarily in the bathroom area.

Last time around I thought this was the grey tank, so I sanitized it with bleach, and the smell went away.

This time around I do not smell anything when I stick my nose right into the shower drain, or sink drain (ie. grey tank). I similarly don't smell anything inside the toilet itself. And yet, the bathroom does stink.

I've checked inside bathroom cabinetry - no leaks or other issues. I've gotten up on the roof, popped the rain cap off the black tank air vent and looked inside - no obstructions.

My black tank currently has about 2 gallons of water, and 2 scoops of "RV Campers Happy RV Toilet Treatment" (less than one scoop is "necessary" for our black tank size, as per instructions). The smell persists.

Could this be something in the grey tank, again?

Could this be something on the upper "walls" of the black tank, where the current water amount does not reach?

[Eagle5]

I recommend that you put ½ cup of Borax (total) into the Grey tank. Share the ½ cup of powder down the drains of the sinks and shower, flushing it down with water. I also recommend using the same ½ cup of Borax in your black tank.
I would throw-out the "RV Campers Happy RV Toilet Treatment"
Eagle5

[eatSleepWoof]

Originally Posted by Eagle5

I recommend that you put ½ cup of Borax (total) into the Grey tank. Share the ½ cup of powder down the drains of the sinks and shower, flushing it down with water. I also recommend using the same ½ cup of Borax in your black tank.
I would throw-out the "RV Campers Happy RV Toilet Treatment"
Eagle5

Thanks, Eagle5.

Does borax do a good job of breaking down toilet paper and everything else that goes down the black tank?

Do you do this 1/2 cup treatment every time before heading out camping, or on some other interval?

Do you keep any water/borax in the tanks after you've dumped and come home?

[Eagle5]

Yes, Borax does a good job in breaking-down the toilet paper, etc.
I just use the ½ cup treatment as I prime my tanks heading-out.
I flush my black tank and drain my grey tank for storage without adding any Borax at that time.

[eatSleepWoof]

Got it. Thanks, will try that approach soon!

[Morich]

Treatment can help but it is rare to find a closed space which has had that stuff in it that won't smell!
If you are sure to keep water in the traps and/or stopper them, there may be another point to check. We don't get the best info on the trailer group but there is frequently an "air admittance valve" in the plumbing setup of RV.
As water is drained from places like the sink, it can run down the drain and create a vacuum effect to draw the water out of the trap under the sink. An attempt to relive this problem is the valve to let air be sucked in as a way top do away with the vacuum.

The problem is that they are not always as reliable as we need. Often just a simple flap to moves as the air pressure changes! Being so simple and lightweight, it doesn't take much to let them hangup and leave a space where the fumes coming from the tank are stopped by the trap but come up and out the air valve!

Maybe worth a look up and under the sinks for what looks like a pipe with just an end sticking up?
If you have one and it is stuck, maybe the odors are coming in there?
One way to test is to cover the valve and seal it, then wait to see if the problem goes away. Maybe a zip-loc bag taped and sealed over the end?

During this time, be aware that the water in the traps may be sucked out and need to be replaced to stop odor in that direction!
We don't want to fix one smell and create a different way to get it!

Some info here but they come in lots of different colors and types, screwed on are nice but glued may also be there!

https://www.bhg.com/home-improvement...ittance-valve/
https://www.lowes.com/pd/Keeney-Plas...-Valve/1069119

[eatSleepWoof]

Originally Posted by Morich

Treatment can help but it is rare to find a closed space which has had that stuff in it that won't smell!
If you are sure to keep water in the traps and/or stopper them, there may be another point to check. We don't get the best info on the trailer group but there is frequently an "air admittance valve" in the plumbing setup of RV.
As water is drained from places like the sink, it can run down the drain and create a vacuum effect to draw the water out of the trap under the sink. An attempt to relive this problem is the valve to let air be sucked in as a way top do away with the vacuum.

The problem is that they are not always as reliable as we need. Often just a simple flap to moves as the air pressure changes! Being so simple and lightweight, it doesn't take much to let them hangup and leave a space where the fumes coming from the tank are stopped by the trap but come up and out the air valve!

Maybe worth a look up and under the sinks for what looks like a pipe with just an end sticking up?
If you have one and it is stuck, maybe the odors are coming in there?
One way to test is to cover the valve and seal it, then wait to see if the problem goes away. Maybe a zip-loc bag taped and sealed over the end?

During this time, be aware that the water in the traps may be sucked out and need to be replaced to stop odor in that direction!
We don't want to fix one smell and create a different way to get it!

Some info here but they come in lots of different colors and types, screwed on are nice but glued may also be there!

https://www.bhg.com/home-improvement...ittance-valve/
https://www.lowes.com/pd/Keeney-Plas...-Valve/1069119

Thanks, that's a good idea, too.

I'm quite familiar with the concept/valves you're describing. Don't remember seeing them in the trailer, but I'll have a second look.

[eatSleepWoof]

Yesterday I filled up the grey tank w/ water and a cup of bleach. Let it sit overnight, dumped it this morning. Filled it up again, this time with half a cup of borax powder. Will let it sit overnight, dump it again tomorrow.

Also put half a cup of borax into the black tank, along with probably a gallon of water.

Really hope that we'll be smell-free tomorrow!

I had a look under all water fixtures in the bathroom. Underneath the shower is a simple drain; no p-traps to be found, just straight across and down into the tank. This can easily result in bad smells from the grey tank coming up.

The bathroom sink does have a p-trap which looks just fine. No air admittance valves. I did also notice this strange little thing:



One of the black hoses runs to the black-tank-flush fixture, the other straight down through the floor, presumably into the black tank. Anyone know what the heck this device does?

[Morich]

Two points to help clear confusion, perhaps?
The item under the shower is likely to be a different form or method of sealing the odors.
Instead of the older p-trap, this is something like a one way valve gizmo!
Inside there is a form of "flap" which closes to keep odor out. but when water goes down, it lets the water pass on through!

I will have to take a look to see if I an find a drawing for them as well as name! About all I know otherwise is that running something hard like a drain snake down may push past the flap gizmo but tear it up getting back out!


The waste flushing line is also something like an air admittance valve. When you put water in to flush the tank, we don't want any chance of waste from the tank being sucked back into the water hose when we turn off the water.
YUCK in the hose and water system?
One way to avoid any suction as the pressure is removed is to let air go in at this valve, rather than any possibility of sucking water out of the tank! It is placed higher than the tank or water connection to make water go way uphill to get in the tube!

Does the black pipe way back in the corner go all the way up and vent at the roof? That would mean no air valve as air can suck in from the roof vent. Air admittance valves are more often found where there is some reason not to run a vent pipe up and out the roof.
I'll do a bit of search for the names ?
If anybody has the name, feel free to pop in with the info!

It has a name but not in my memory bank!

[Morich]

Found some names from a motorized Rv with same functions!
Click for best view!


Idea is that the flushing water that comes in the blue tube closes the valve and goes down to the tank on the red hose.
When you shut the water off at the hose, water going back down the blue hose might try to suck water out of the tank and into the plumbing. Any cross connection from waste to fresh is not allowed by code, so the valve will let air in to avoid and suction from the waste tank!

I've not had one at any time but it has always made me wonder how often they might stick open a bit and let incoming hose water leak into the wall space???
Just one of those paranoid things I think about!

[eatSleepWoof]

Thanks, Morich. Great info all around!

My wife and I both suspect the shower drain as the source of the smell, especially since the smell briefly gets better (disappears) when taking a shower. It does come back afterwards though. A partially stuck-open valve in that section seems like a likely culprit.

[Morich]

UGH! One of my worries about new stuff is how they will hold up over th elong haul. The waterless trap sounds good in some ways as it does let them put the floor of the shower lower than using a trap.
But when I think of all the stuff like soap scum, hair and lots of yuck stuff that goes down even a shower drain, it bothers me.
As I have heard these described, they are a plastic tube like PVC pipe but with a thinner inside "flap"? If that flap is thin enough to open when water runs into it, that has to make it pretty thin, it would seem.
One thing I find in most plastic is that it tends to get a little bit brittle and hard over time. Like plastic on kids toys or small items like that? So what does the plastic in the waterless trap do after some time with soap trying to clog it up and just time letting it degrade?

Maybe time to do some checking to see what happens if you can figure a way to seal off the whole drain for some time like when stored?
Too bad our noses are not as good as a dog or cat?

[eatSleepWoof]

I wonder if I can find a push-on/push-off cap for the shower drain. I used to have one of these in a residential bathtub. That would work for sealing off the drain when the shower is not being used...

[Morich]

For flat drains like some showers, there used to be rubber type with suction type on the bottom? But that may be time to "invent" something to test.

I watched a couple ball games over the weekend and it always makes me giggle when folks decide the refs were at fault! Sometimes it is not the quality of the players but whose coach has a trick saved for the crisis. Finding the rookie D-back is one the Kansas City coach is pretty good at doing!

[eatSleepWoof]

Dumped the grey tank after it sat 24hrs w/ borax. There's still a smell present. Perhaps not as strong as before, but it's tough to be subjective with smells.

Filled up the tank again, this time with two cups of bleach. Will give it another 24 hours.

This time I kept filling up the tank well beyond the "full" indicator on the panel. I ran the shower for about the first 1/3 of the tank, and then ran the kitchen sink.

This sink is the one that started backing up with water once the tank filled up. The shower did not get any water in it, so the valve in the drain does seem to be closed. However, after a few minutes that valve did start to make a gurgling noise, like air coming up it. That lasted for about 5-10 minutes and then stopped.

I also ordered a plug which will allow me to close-off the shower drain. I'll try this out if the smell persists after tomorrow's dump.

Failing that, I'll move on to the black tank. This video does a nice job of comparing common RV black tank products. It clearly shows that my highly-recommended "happy campers" RV treatment does virtually nothing, and that two products that DO work are "Unique RV digest-it" and "Liquified" RV treatment. Will look for those.

https://www.youtube.com/watch?v=iTo36_zgLkk

[Blue Sky]

Check your vent to make sure it's venting.

[eatSleepWoof]

I had a look at the vents - they're clear.

Went to dump the grey water this morning and it seemed like the smell was gone, although I was not 100% sure.

I also stumbled across approximately a million online complaints about the Dometic 300 toilet (which I have) emitting a smell.

Turns out the toilet has an inner and outer bowl, which are separated by two rubber gaskets that stack on each other. Sitting down on the toilet appears to create a vacuum effect, which pulls the unmentionables in through/between those two gaskets, and into the outer bowl. It builds up and causes bad smells.

I watched some videos on YouTube with folks replacing their 300 series toilet as many as 3 times, each time ending up with the same issue. Seems to be a design flaw. Fixable in a DIY settings with some silicone or other sealant, if need be.

Will tackle this if flushing out the grey tanks does not resolve the problem.

[Eagle5]

My Dometic 300 toilet dumps straight-down; directly into the center of the Black Water Tank. Could it be that the problem is only found on installations where there is a sewer pipe 90º angle installed between the toilet and the tank?
Eagle5

[eatSleepWoof]

Mine also dumps straight down. It seems like there are some gaskets along that vertical "flow". The video I watched showed the owner removing the toilet, and his setup was exactly the same as mine. He's the one that replaced his toilet 3 times before finally opening it up to do a DIY fix.

Here's the video if you want to have a look:

https://www.youtube.com/watch?v=4_ChfCv9T1k

[reeman]

We use a flat stopper on the shower drain. The traps never have water in them so it is inevitable that the stink from the grey water tank will come up there. And yes some Borax or liquid with the same chemical is a possible choice. Chlorine based liquids are not the right chemical choice and will only bind with fats and cause buildups in pipes and tanks. But most likely one just needs to seal off the shower and sink drain with stoppers and let the gas escape up the vent as designed.
If the toilet seal is encrusted or damaged then it can also easily allow sewer odours through so properly cleaning and inspecting the gasket seal on the toilet flush valve is also very important. It is also very easy to harm that seal on the toilet if one aggressively uses a flush wand and does not protect the seal from damage from the pipe hitting the gasket and inner valve seal surfaces in the process of flush cleaning the black water tank.