2108 tb after dump smells

[jrh47]

I have a 2108TB and it smells awful for days after a dump of the black tank. It's odd that I can sit and dry camp for 4-5 days and notice no smell until after I dump, then it bad for several days afterward. I took it in for service once and they found no problem. They checked for leaks and vent issues too. Have noticed this on several trips. I have lately started trying out a youtube idea of using Borax, Dawn dishwashing soap, and water instead of chemicals and it seems a little better. Apparently the chemicals I was using only magnified the smell? Does anyone have any ideas about this problem?

[Marine359]

This is a guess, but worth checking. There could be a leak in the tank or more likely one of the fittings at the bottom of the tank. Possible that only when dumping (due to rush of liquid), some liquids could get trapped inside the duraplast underbelly. The liquid could stay there for several days until it gradually drips out through the lowest opening in the membrane or dries out, dissipating the odor. Have you noticed wetness anywhere under the trailer? (Liquids can migrate on top of the membrane). If I were troubleshooting this, I would poke a hole in the membrane, or several holes around where the drain pipe exits the membrane. Afterwards, repair with membrane tape.

[Marine359]

If you find there are no leaks, then the odor has to be coming from inside the tank. Over time sludge can form on the inside of the tank. Even if you use the outside tank rinse hose connection, sludge buildup can remain on the inside of the tank. If tank is full or partially full, you may not smell the sludge. When you dump, the sludge gets exposed, and whammo. You can inspect the inside of the tank with a scope. But very likely the easiest solution is to pour in a gallon of septic sludge dissolver, and then fill the tank 2/3 with water. The key is to drive around on a country (bumpy) road for ten miles so the solution sloshes around in the tank. Then dump, then add some deodorizer and a gallon of water, and your tank will smell fresh as a daisy. This worked for me when we bought an old motor home to refurbish. Sludge had dried out, and as soon as we used the toilet, odors were reactivated. So, I imagine this can happen in a MM if winterized without a good tank cleaning.

[jrh47]

Thanks for your reply Marine359. They actually cut the membrane and looked in there when it was in for service for this problem and found no leaks. But that was a month after the original first issue with the smell and of course, it was gone by then. I will definitely try poking a few holes under the tank to look for leaks like you suggested and will try the sludge remover too. I am the only user so I don't think it's buildup? This is not my first RV so I know better than to use it without water in it. But will try your suggestions thanks again.

[Twpinaz]

Had similar issues with lingering smell/out gassing and tried the boric acid and dawn suggestions with minimal success. I changed to happy camper black tank treatment and won’t use anything else. It broke down whatever is in the tank and cleaned out anything that may not have flushed out before. No more smell.
Decided to do a couple of additional things after I got rid of the smell.
I don’t have built-in tank rinsers, so I bought the gate valve to back flush the tanks. Also added a camco cyclone on the sewer vent tube (pulls any black tank gas out of the coach).
The happy camper works and I won’t use the drop ins ever again.

[Morich]

Where and how do you store the hose after draining?
If not rinsed well the hose can have enough debris in the grooves to smell if it is stored at the right place.

The tank has a vent which is expected to carry any fumes up and out on top so that we don't often smell them and it is also important to note that a tank full of waste is likely to smell much more and longer than a tank which has been emptied, so the fact that draining seems to cause the smell makes me feel it is not from the tank but something outside the tank.

Another point to consider is that it might not be the black tank but you will know how and when you are dumping.

So if you dump both black and grey at the same time, is it possible/likely that you could confuse grey smell for black?

There are often vents on the grey lines and tanks which are hidden up under things like the vanity and should let air IN as you drain the vanity sink but can stick at times so that they don't close and let odors come inside. Maybe a check under and up where it is out of normal sight would find one which might be sticking?

Only suggestions of things which you might be missing.

[Wyatt]

I made the mistake early on when our unit was brand new, (so no long term built up sludge), of emptying my tank at the campground before heading home, without taking the time to rinse it out first.
I would reek on the drive home, even though the toilet seal was holding water in the commode.
By back-flushing it before leaving, and adding enough water to cover the bottom of the tank, (5 gallons), it has solved my issue.
When I get home, I do even a more thorough cleaning with a wand down the toilet that has a spinning spray valve at the end.
It’s amazing how much more comes out after that.
Someday I’m adding a real black tank flush device. Much easier than what I’m doing now...

[dkoldman]

Originally Posted by jrh47

I have a 2108TB and it smells awful for days after a dump of the black tank. It's odd that I can sit and dry camp for 4-5 days and notice no smell until after I dump, then it bad for several days afterward. I took it in for service once and they found no problem. They checked for leaks and vent issues too. Have noticed this on several trips. I have lately started trying out a youtube idea of using Borax, Dawn dishwashing soap, and water instead of chemicals and it seems a little better. Apparently the chemicals I was using only magnified the smell? Does anyone have any ideas about this problem?

I would love to know what chemicals you have been using? I have been using Thetford for so long, I refuse to even try ANY thing else that is not free or I would have to pay for. Thetford works; so I don't need to fish for a product that may works more. I would not argue with anyone who may they have something they feel works better than Thetford. With that said, if you camp for 4 - 5 days with no smells, I would suggest that what ever you use works too.

Since you only get the smell when/after dumping, I would focus on your process. Have you tried to dump gray tank only to see if you get the smell? Gray smell can be worse and maybe it is NOT treated and has some stronger odor based on how you use.

Do you flush Black tank? If so; it would be impossible as source for a lingering odor that would somehow otherwise go away when you start to use it

We don't use our flex sewer hose much any more, but when I do, I sit them in position to drain and get outside air before storing. We have 3/4" hose that connects to Jet Flo Macerator and dump it home. I keep the 100ft hose at home and NOT in RV unless I travel someplace where I think I may need it based on where we are traveling to (i.e if I go visit a relative / friends house)

[Morich]

I also lean toward checking the process used. When you think of what access points the black tank has to the inside, there are really limited areas. One is the stool but if you are doing the draining correctly, there should be water left on top of the stool seal to keep odors out there, assuming the stool to floor connection is good. And then the only other black water odor access should be the vent pipe which is supposed to be high and away where we would not expect to smell it inside.

Grey water smells are much more likely to get inside as there are a number of different spots, one at each sink and then the airgap devises.

But if there is spillage at the wet bay or inside the hose which is then stored inside, the odor can be easy to sneak inside .

That is is noticed after getting rid of most of the stuff that smells seems to point toward something wrong with the draining process. A gallon may stink but 30 gallons will stink a lot more and a lot longer!

[jrh47]

Thanks for your reply Twpinaz. What is the gate valve to backflush the tanks? I use an attachment that goes on the end of a hose and sticks down the toilet to rinse the black tank. I will double-check but I think the sewer vent already has a cyclone on the sewer vent tube?

[jrh47]

Thanks for these suggestions Morich. I wonder how I could check these check valves on the gray tank to be sure they are closed. They did replace one of the cyclone vents on the kitchen sink but it did not help.

[Morich]

I have some small ideas of how to test one but they are pretty "home-made" and I do not know of a real test as dealers often just replace, rather than test.

First we might talk about the how and why these gizmos are there as they are so simple but so tricky!

We have a trap under most sinks and lavatories on the Rv just as we do at home but on RV we don't find it good to make lots of vents through the roof like we do at home, so they use these air gaps more often. At home they just run a small pipe up and out the roof!

I made a drawing of how the trap and air gap are supposed to work.

When we run water, there is a certain amount designed to stay in the loop at the bottom called the trap. This water filled trap acts as a plug to keep odors and dangerous gas from coming into the house from the sewer. You can see it in the bathroom stools as the standing water so imagine the same at each sink, vanity, etc.

When water flows down the pipe as we flush or drain the sink, it can create a vacuum as it goes down the pipe as this vacuum can draw all the water out of the trap, leaving it open to let gas smell into the house. But to keep that vacuum from drawing the water out of the trap, we add a vent on all pipes in this situation. I've drawn this vent mechanism as a green line on the drawing, just to make it simple to imagine.

Normal operation in RV is that the flap opens easily to let air go in the pipe to relieve the vacuum and leave water in the trap. Works fine most of the time and if you crawl in under the sink or vanity to look up at the pipes, you may see this as a small section of "pipe" glued on the top of the upright drain pipe.

BUT two things can happen to the airgap. One is that it sticks OPEN and lets gas and odor come back up the pipe, through the vent and we smell it!

Two is that it may stick CLOSED and that lets the water falling down the drain create enough vacuum that the water sealing the trap is also pulled out, leaving an open path for odors to come up, through the trap and inside!

Both of these situations depend on lots of variables like how much water draining, how long the drain, what angle, etc, ect. but they can happen pretty easy with a small (cheap?) plastic gizmo, so it may need checking.

This is technically more correct to be called an "air admittance valve" when shopping and this is a link to one to show a number of things. Like how easy it is to change if it screws in, but I expect them to be glued!
https://www.amazon.com/Oatey-39012-A...07402370&psc=1

Testing? One way is to cover it with something like cling wrap to rubber band a solid seal over the vent to see if the odor stops and also to make sure there is water standing in the trap before taking off to drive. The water can sometimes be slopped out of the trap it we get into steep, wild driving!
If we are stopped and setting AND if we are lucky enough to have a drain plug which holds water long term, we can fill the basin with water. Then it is trial and error to see what stops the problem.

But if you are lucky enough to find it is only screwed in, changing a $3-4 item may be the better way to go?

IF you are a DIY person, cutting the pipe and old gap out to replace it with a pipe fitting so the next one can be screwed in is a good move. One of the new little oscillating tools is great for working under sinks to cut pipe.

[Morich]

Correction/update?

I finished my coffee and wandered out to look at the the RV, so took a look at the air gaps!
On the 2015 Vista, they are both just a screwed in fitting, so my thinking would lean toward just changing them out if I had odor questions!
I doesn't take much to get me to spend under five dollars if it can cut the stress!

[Mstench]

I had the same issue, I found a place in Florida that actually will pressure wash and sanitize the inside of the tanks, and yes it was full of a pancake batter type sludge. After the sanitize was done I had no more smell issue and as a bonus my sensors worked great. Good Luck and hope you find the answer

[NeilV]

Often odors are from the air gaps or due to the water traps in the drains under the sinks getting sucked dry when dumping or simply from evaporation especially if there is a washing machine hookup that is seldom or never used or if you do not use the shower. Without water in the traps odors will easily enter the living space from the tanks.

Note that some models may drain the bathroom sink into the black tank so yes black tank smells can migrate in through the bathroom sink however food waste in the grey tank can fester and make for a worse odor than from the black tank. Ask anyone who works in a restaurant and been around when the grease trap on the kitchen drain line is being emptied.

[Wyatt]

Originally Posted by NeilV

Note that some models may drain the bathroom sink into the black tank so yes black tank smells can migrate in through the bathroom sink however food waste in the grey tank can fester and make for a worse odor than from the black tank.

Ask anyone who works in a restaurant and been around when the grease trap on the kitchen drain line is being emptied.

Oh yeah, that dreaded grease trap! You brought back some unwanted memories...

[imnprsd]

Here's my 2-cents....

Heat brings out the odor and is your worst friend when it comes to holding tank odors.

Gray water can smell worse than black water, but I find the TST Gray Water additive works well and you can get this stuff at Wallmart.

* Try not to put food and cooking grease down the drain.

* Anaerobic bacteria smells. I.e., blooms occur when it's hot and when there is no oxygenation.

==> I have added Boraxo to help, and while I have got some success, it's never enough when I start driving. Then the smell will go away... probably because I'm oxigenating the tank muck by driving.

* Good bacteria in the tank helps to keep odors down, but when you sanitize your holding tank (mostly the black tank) it kills the good bacteria, so you either have to so a SUPER CLEANING over a 100 mile trip with a very high concentrated cleanter; or you should just rise your tank after every flush; and drive around with a lot of fresh water in your holding tank so you can drain it when you get to your camping spot.

I also try NOT to use the tank fragrance products in the black water tank.

==> In the good old days formaldehyde worked really well, but you can't buy that stuff any more. Not at an RV store or Walmart.

==> So I have been using a full bottle of ZEP Septic Defence treatment and try not to empty that often. $9/64 oz bottle.

https://www.homedepot.com/p/ZEP-64-o...T648/100010585

Note: WD now makes a Cleaner Degreaser NEW Product I have only been able to order on Amazon and it is a great cleaner. I use it in my shower at home on the tile and on my Harley chrome. AND... it does not smell!!!! ...So I plan to clean my gray and black water tanks with this stuff and see if that cut through the buildup in side the tank. TBD.

Some tanks are a losing battle, but that doesn't mean there isn't a solution out there. Every year they keep coming up with new formulas. Hopefully this Zep stuff will prove worthy. TBD.

[Twpinaz]

The gate valve connects right before your sewer hose. On my iPad and can’t add a picture, but search on Amazon using camco gate valve and you will see several different ones. The gate valve allows you to isolate/close off your black or gray tank and you connect a water hose to it and fill up the black or gray tank from the sewer hose connection side. Just be sure to use a different hose than your drinking water hose. Turn water off and then open slide gate and drain. Similar in how your black or gray gate valves open and close. You can fill and flush your tanks until they drain clear. I find this much easier than routing the wand and hose to the toilet.
The happy camper is an organic tank treatment I use on both the gray and black tanks and am very happy with. Tried others and found this works best for us, as with every cleaner I believe everyone has a preference and you need to go with what works for you. We had built up sludge in the black tank and it broke it down when others just masked the smell. Like Wyatt mentioned adding 5 gallons after flushing the black tank is the sweet spot to keep the bottom of the black tank covered. Doing all of this saved us the expense of having the tank professionally power washed.

[Grandparat1]

I've never tried it but another way I'm told to elimate the tank sludge is put a couple of bags of ice in the tank and drive around while it breaks things loose. That, along with the anti-sludge solution someone else mentioned. It cant hurt I guess.

[Morich]

But the point missing on smells from the tank is that the system is designed to vent the odors out at the roof line and NOT inside, so if there is smell inside, it seems to be a failure in the venting.
I think of waste tanks as always having an odor, the trick it keeping it outside. I don't work very hard to keep odor out of the waste tank because one trip to the bathroom will undo anything I try!