Black water odor while driving

[InterBlog]

Originally Posted by SteveJ

....
Options appear to replace with a new toilet every couple of years, lose access to the cabinet, go to a porta potti option, or live with the stink with a lot of air freshener.
....

Or install a powered tank vent in the roof to compensate for it, such that the wet bath is kept under slight negative pressure. Except I don't think that there are any good powered vents on the market right now.

[InterBlog]

To reiterate, the very design of the cheap gravity toilets that are on the market thwarts our ability to keep proper seals.

Hence my three independent blog links early in this thread: three dedicated owners with DIY skills all trying to solve the same problem, and all failing repeatedly. Logic suggests that the problem, then, is not with the operators but with an unsalvageable design.

Fix a Thetford seal and there's a good chance it will be broken once again after about ten miles of standard pothole impacts. That's the problem, not the operators.

[DUTCH in Atlanta]

Originally Posted by InterBlog

Fix a Thetford seal and there's a good chance it will be broken once again after about ten miles of standard pothole impacts. That's the problem, not the operators.

My Thetford toilet as ridden more 11,000 miles over some very rough and bumpy roads, and it still seals just fine. No odor.

[InterBlog]

Originally Posted by DUTCH in Atlanta

My Thetford toilet as ridden more 11,000 miles over some very rough and bumpy roads, and it still seals just fine. No odor.

Then that makes you one of the lucky ones, eh?

Here's a pic of our old Thetford turned upside down and placed on a step stool, because we had filled the interstices with water to show how it leaks out through one or more broken seals. See that big water stain on the driveway? The water poured out through those seals.

The other two bloggers I linked have also published analogous photos. ClassBWarned has a video showing water actively leaking out of his.

[SteveJ]

Originally Posted by InterBlog

Then that makes you one of the lucky ones, eh?

Here's a pic of our old Thetford turned upside down and placed on a step stool, because we had filled the interstices with water to show how it leaks out through one or more broken seals. See that big water stain on the driveway? The water poured out through those seals.

The other two bloggers I linked have also published analogous photos. ClassBWarned has a video showing water actively leaking out of his.

Thanks for the links. Lotsa good info and quite helpful.

[SteveJ]

Originally Posted by InterBlog

Or install a powered tank vent in the roof to compensate for it, such that the wet bath is kept under slight negative pressure. Except I don't think that there are any good powered vents on the market right now.

It's nice to have options, thanks. Off to the interwebs...

[Bud]

Originally Posted by InterBlog

Or install a powered tank vent in the roof to compensate for it, such that the wet bath is kept under slight negative pressure. Except I don't think that there are any good powered vents on the market right now.

What does that say???

Me, 100,000+ miles and never one smell from black or gray.

Sure enjoy your posts, liked the stainless tray.

Bud

[DUTCH in Atlanta]

Originally Posted by InterBlog

Then that makes you one of the lucky ones, eh?

Yup, or just a quality product!

[avanti]

Well, I am no expert on toilets. This is because I have never had occasion to become one. I have owned two different toilets, one plastic and one porcelain, over a period of 14 years. I have never had leakage or odor issues. I do not use chemicals of any kind. I have long ago concluded from this that if an RV bathroom smells, then it is broken.

Maybe there are design flaws in some Thetford models, I really don't know. Clearly, others have explored this issue far more than I have. But, the story isn't as simple as "gravity flush toilets smell". Dunno.

EDIT: In a previous version of this post, I incorrectly claimed that my two toilets were Thetfords. This was incorrect. My current one is Dometic. Not sure about the previous one.

[InterBlog]

Originally Posted by Bud

What does that say???

...

Well, I could produce a list, but just for openers, it reflects the fact that Class Bs represent only a tiny market share, such that the demand for supplemental devices of that type is correspondingly small.

We live in *dramatically* closer proximity to our toilet, black tank, vent, plumbing lines, etc. than do people in most rigs on the road (in my case, mere inches, because the wet bath abuts the driver's seat). I've noticed odors in multiple other types of rigs with similar gravity toilets (boats, too), but when the wet bath is situated ten feet away instead of ten inches, it tends not to become as much of a focus issue.

Here is Roadtrek Life's DIY on a solar powered active venting mechanism. For those of you who are not familiar with this guy, he's pretty much the gold standard when it comes to van DIY retrofitting. Forget about his unfortunate association with the Roadtrek name - he has no connection to the Wendlands.

https://roadtreklife.blogspot.com/20...tank-vent.html

[InterBlog]

Originally Posted by DUTCH in Atlanta

Yup, or just a quality product!

In someone's wildest dreams, perhaps, but not ours.

So that readers do not have to click and drill down, here below is a reproduction of ClassBWarned's GIF of his leaky "quality product" Thetford which, by the way, was new when he shot this.

Look how fast it's coming out. Now visualize poopy black water being sloshed up in there and coming out the same way. Or maybe if the poop does not rise as high as that level, just the odors as the air escapes.

[Bud]

Originally Posted by InterBlog

Well, I could produce a list, but just for openers, it reflects the fact that Class Bs represent only a tiny market share, such that the demand for supplemental devices of that type is correspondingly small.

We live in *dramatically* closer proximity to our toilet, black tank, vent, plumbing lines, etc. than do people in most rigs on the road (in my case, mere inches, because the wet bath abuts the driver's seat). I've noticed odors in multiple other types of rigs with similar gravity toilets (boats, too), but when the wet bath is situated ten feet away instead of ten inches, it tends not to become as much of a focus issue.

Here is Roadtrek Life's DIY on a solar powered active venting mechanism. For those of you who are not familiar with this guy, he's pretty much the gold standard when it comes to van DIY retrofitting. Forget about his unfortunate association with the Roadtrek name - he has no connection to the Wendlands.

https://roadtreklife.blogspot.com/20...tank-vent.html

"There are times that the RV black holding tank creates a source of undesirable odor within the coach, especially during hot summer months."

I've read and benefited from this fellows experiences and mods. I'm too lazy to go back and read. Does he provide a reason for the quote above?

[InterBlog]

Originally Posted by Bud

"There are times that the RV black holding tank creates a source of undesirable odor within the coach, especially during hot summer months."

I've read and benefited from this fellows experiences and mods. I'm too lazy to go back and read. Does he provide a reason for the quote above?

Cheap gravity toilets are often not air tight.

I, too, notice a much worse problem during hot weather, and during temperature and elevation changes. The last straw for me came when I transitioned from the Shenandoah Valley up into the mountains of the National Park a couple of years ago. That change in temperature and elevation caused the odor to become even worse. When I rolled down the driver's window to pay the park fee, I just know that the attendant was hit in the face with a blast of sewage stench. I felt bad for all of us.

After that indelectable experience, we got a Dometic toilet which is still not perfect, but it's better than the Thetford, odor-wise.

Eventually if I live long enough, I will install a powered tank vent. One way or another, I'll figure this out.

Edit: Parks Canada has begun adding better-designed venting in its pit toilets. There are some of the new type in the Cape Breton Highlands National Park. If you walked into one of them blindfolded, you would never know that you were standing in front of an exposed mountain of human waste. I haven't yet looked into how they do their design. I'll try to take pics later this summer.

[GeorgeRa]

Originally Posted by InterBlog

Cheap gravity toilets are often not air tight.

I, too, notice a much worse problem during hot weather, and during temperature and elevation changes. The last straw for me came when I transitioned from the Shenandoah Valley up into the mountains of the National Park a couple of years ago. That change in temperature and elevation caused the odor to become even worse. When I rolled down the driver's window to pay the park fee, I just know that the attendant was hit in the face with a blast of sewage stench. I felt bad for all of us.

After that indelectable experience, we got a Dometic toilet which is still not perfect, but it's better than the Thetford, odor-wise.

Eventually if I live long enough, I will install a powered tank vent. One way or another, I'll figure this out.



Edit: Parks Canada has begun adding better-designed venting in its pit toilets. There are some of the new type in the Cape Breton Highlands National Park. If you walked into one of them blindfolded, you would never know that you were standing in front of an exposed mountain of human waste. I haven't yet looked into how they do their design. I'll try to take pics later this summer.

Interesting but risky design with opening mechanism in the black tank’s space. My previous RV had a ball valve with a pedal with direct down flow and sealed bowl to black tank. My cassette is sealed directly to bowl with rotating blade flush valve. This Thetford toilet design has to potentials flows:

- Large welded or glued seam if cracked will let black water gas into the living space. This seam is exposed to repeatable compression stress by user’s weight.
- Open space for flush mechanism will be sensitive to location on the black tank, distance to black tank and the black shape. Slushing of black water due to acceleration, deceleration and cornering forces will vary from RV to RV and could leave various levels of deposit in the uncleanable space.

I would look for a toilet, Thetford or not with:
- No free space between bowl and black tank
- External flush valve mechanism sealed from black water space.

Pictured copied from previously listed link.

[rtbill]

A very interesting thread! We have been puzzling over sewer odor in our Roadtrek '00 200 for a while now, even with a new toilet and having reseated it twice with new seals. I did not know about the overflow tube in Thetfords. Will have to check the flush cable seal.

The joint between the top and bottom of the exterior of the toilet is sealed with an o-ring. On the first replacement toilet I got, about 8" of the o-ring was hanging out of the joint on the inside of the toilet. Amazon sent a free replacement.

The vent fan is an interesting idea I may have to pursue.

[avanti]

My previous post in this thread incorrectly said that my toilets have been Thetford. This is incorrect. My current porcelain one is Dometic. Perhaps my old plastic one was too--don't remember.

Maybe this is why I have never had order problems?

[InterBlog]

There are two toilet-related threads populating at the same time here, and it's making my head spin. This one and "crappy situation".

BTW, it goes without saying that, no matter the source of odor (leaking toilet, vent not working adequately, or other issue), we will all get better results by gravity dumping with updated equipment.

I don't have a macerator but several weeks back, I switched to a Rhino dump hose, which required a SuperSlider installation because the Rhino will not fit into a conventional gravity dump holder such as those sold by Valterra, because they are too narrow.

I'm very glad I did this. I no longer have to engage in guesswork to know when my black tank is truly cleaned out (I flush it manually). See that transparent piece on the left hand side of this assembly? That will tell you everything you need to know. Much, much better than an old-style opaque hose.

[avanti]

Originally Posted by InterBlog

I no longer have to engage in guesswork to know when my black tank is truly cleaned out (I flush it manually). See that transparent piece on the left hand side of this assembly? That will tell you everything you need to know. Much, much better than an old-style opaque hose.

Yes. Having a transparent section somewhere in the dump path is huge. It is the sanitation equivalent of having a battery monitor (well, almost).

In my case, I added a transparent bayonet cap when I upgraded to a dual-dump setup. The tanks both drain to this point and the macerator pumps out of it. It shows the flow rate very clearly. If I ever had to do a gravity dump, this cap would be removed. Has never happened so far.

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[GeorgeRa]

I have an older model power vent from this company SUPER STANKER Sewer Tank/Vent Pipe Fan - Overview Page but I think they are out of business.

[Bud]

Originally Posted by avanti

My previous post in this thread incorrectly said that my toilets have been Thetford. This is incorrect. My current porcelain one is Dometic. Perhaps my old plastic one was too--don't remember.

Maybe this is why I have never had order problems?

Plastic here for 100,000+ miles, no odor.

Bud