Bathroom odor

[FlStrmr]

OK, I hate having to post this thread but I need some insight from experienced Airstreamers. I have a new 2018 Grand Tour. My wife and I have taken a couple shakedown trips and we have a persistent bad odor from the toilet. We've only Number 1'd, no Number 2's!! We flush generously but the next day the residual fluid in the toilet has turned from clear to pale yellow and smells. I've completely emptied the black tank, flushed it out, and added fresh water with TST Toilet treatment. If I leave the ceiling vent open the smell dissapates but otherwise it will smell like a construction site portapotty. Any suggestions? The toilet valve seems to be operating correctly. Is there another check valve that might be malfunctioning?
Is back flow from the black tank possible?

[InterBlog]

Does your Interstate have the Thetford Aqua Magic model of toilet in it?

If so, you might want to read this blog post which describes its design flaws (and provides links to corroborating testimony by others, including the blogger Road Trek Life who went through at least three installations).

To summarize, that model is neither water tight nor air tight. Or, maybe some units begin their lives in an air tight state, but not necessarily all, and among those that are initially tight, anecdotal reports suggest that they don't last. Ours certainly did not.

There is also further discussion of this issue on this Air Forums thread.

[AirstreamInc]

Hi FlStrmr,

We're sorry to learn about the odor you described in your 2018 Interstate Grand Tour Ext. Please call our customer service and technical support team at*1 (877) 596-6111, option 2 so we can learn more and help.

Thanks.

[Pahaska]

I replaced the Thetford with a ceramic Dometic 310. Before that, we had occasional odors. After the change, no odor. Best mod I have made.

[FlStrmr]

OK, here's the update to my problem. I called AS Tech support at their invitation. No resolution but they confirmed I have a Dometic 301 and they identified some local Dometic dealers for possible service. Afterward, in my driveway, I used the Black Tank sprayer and filled it with clean water, emptied, and then ran a couple gallons of fresh water through the toilet into the tank and added a sanitizer. After an hour water in toilet stayed clear. Success! (I thought). So then I drove to my storage unit, checked the toilet and the water in the toilet was again yellow and smelling. It seems the jostling of the tank while I drove again put some old fluid back up in the bowl. Tomorrow I'm going to try and do a further rinsing below the toilet bowl valve. Any other ideas?

[Pahaska]

No water should come up in the bowl unless the seal is not working. I have driven 300 miles with my Dometic and had the same clear water in the bowl that I started with.

BTW, don't have much water in the bowl when you drive or it may slosh out on hard turns or hard braking. A friend wondered why his floor was often wet until he found he was leaving too much water in the bowl. The solution is a very short flush.

I might add that I often use the Dometic while the AI is in storage and it might sit for a week or two (with chemicals). I never have odor and clear water stays in the bowl.

[FlStrmr]

Thanks. The whole thing is very strange. Since I cleaned out the black tank I know there’s no urine in there. The seal is holding water so there can’t be back flow there. I’ve flushed and watched the clear water sitting in the bowl and at times can watch a small infusion of the yellow water trickling in from wherever the flush water comes from (whether on city water or fresh water tank). I’m going to explore more tomorrow and if unsuccessful add it to my next service visit.

[Titus]

We have only # 1'd too, and have not noticed an odor other than that from the blue power that we add after each dumping. We sometimes wait a day - until we have accumulated about a gallon of pee and flush water - before adding the blue powder, in order to avoid using some black tank capacity. No reason to add blue powder to a gallon of fresh water. We do notice a bit of pee smell - especially in the summer - when we do this. But that is our fault.