Dometic 310 replacement recommendations

[Scott in Michigan]

I'm done battling the bowl to pedestal seal design flaw of our Dometic 310 series toilet.

Is replacing it with a Thetford RV toilet a reasonable solution, or do they come with their own design shortcomings?

Thanks, Scott

[chuckster57]

I would switch to a 320 toilet if it fits. Thetford is a huge step down IMO

[Scott in Michigan]

Chuck, I was under the impression, though, that the entire Dometic 3xx line has the same bowel-to-pedestal leakage flaw. Scott

[rhagfo]

Originally Posted by Scott in Michigan

Chuck, I was under the impression, though, that the entire Dometic 3xx line has the same bowel-to-pedestal leakage flaw. Scott

News to me!

Believe what you want but our 320, has been a great toilet, only leak was bad flush valve after four years of full timing.

[travelin texans]

Originally Posted by chuckster57

I would switch to a 320 toilet if it fits. Thetford is a huge step down IMO

Totally agree!
You will still have issues, probably more, with the Thetford & parts are much more expensive & most any repairs require removing the toilet for the repairs to be done.
Get the 320!

[sourdough]

I don't guess I'm aware of any inherent flaw in the 310 bowl to ped design? They're all I put in and even removed the OE Thetford in this trailer before the 1st trip. Is the toilet OE or did you install a 310? You don't list year, make etc. of trailer but I believe Keystone uses Thetfords OE as a general rule.

[Scott in Michigan]

All,

I appreciate the replies.* Our unit is a 2018 Cougar 32RLI.
*
After a MICH to ARIZ trip last year (I blame New Mexico's roads) it showed up for us.* Inspection showed liquid at the pedestal to bowl junction.* The tiniest amount would then seep down over the pedestal and collect at the floor.**Turns out the 310 leak was well known.* Of*course, it's not the kind of thing you search*for if you aren't experiencing*it.**

I caulked the bowl/pedestal seam as a stop gap.* A deeper internet search today also showed complaints regarding the 320 leaking from the pedestal to bowl seam.* There apparently*is no difference in their internal design*at this seam.

From your comments, I acknowledge it never shows up for some of us.* Maybe it visits us who log miles on the rougher roadways, quicker?* NM roads were a lot better this year, BTW.

Sounds like the Thetford is not a good replacement choice. *

Does that super water proof tape they hawk on TV really work??**

Does anyone have a tested recommendation for caulk for wet applications? *

Scott

[Mikendebbie]

Scott - it sounds like your Dometic is definitely toast. I went looking for a cross section view and could not find one - but the installation manual warns against separating the ceramic bowl from the plastic base. Sounds like yours must have separated on its own thanks to rough roads. Your toilet is obviously out of warranty being a 2018. If bowl to pedestal base was a common problem for Dometic toilets - Chuckster57 and many other knowledgeable people on this and other forums would know about it. The manual for Dometic toilets shows a blow-up view of the serviceable parts. As you have discovered - bowl to toilet is not serviceable. There are numerous threads going back many years on the Montana forum about trouble with Thetford units leaking. The overwhelming recommended solution is to install a Dometic unit. I looked up your floor plan to see if by chance your rig was a rear bath model (thinking that rear bath units experience the worst of the earthquake jolts during travel) - and it is a mid-bath model - which I would think is one of the most stabile parts of the RV. Don’t spend your money on super sticky leak tape and water seal caulk. Use it to go toward the purchase of a Dometic 320.

It is possible that your misfortune is an rare. The solution you seek may be a bit of a unicorn…sort of like looking for a truck with a Cummins engine, Ford cab interor and an Allison transmission…it does not exist.

[notanlines]

You may find complaints online concerning the 320, but you can find complaints online about free money if you look hard. Make the swap to the 320, install it correctly and move on. It'll be your best move.

[spicercars]

We have had the 320 model in many of our campers over the years with no problems. We have one now in our Montana that's parked at the lake and gets used quite often during the summer.

[JRTJH]

Our Dometic 310 toilet is now 9 years old, has been towed over some of the roughest roads in the US (like I-40 through Arizona and New Mexico and I-70 on Colorado's western slope) with absolutely no problems. If "rough roads and excessive miles" are a problem, it hasn't affected my 9 years and over 50K miles.

There is a known issue with the Dometic 300 (plastic bowl toilet) leaking into the hollow spaces from inside the bowl. This waste water pools in cavities in the toilet base and the odors leak out into the room. To my knowledge, there is no "known problem" with either 310 or 320 toilets and such a leak.

I have no doubt there is a potential for any "two part component" to have a leak, but in this case, I have never heard of an "ongoing issue with the 310 toilet leaking"....

That said, any (and I mean any at all) attempt to seal the outside to prevent a leak from reaching the floor of the trailer will increase the probability of that stagnant water pooling inside the toilet base and will virtually "guarantee offensive odors".... DO NOT tape the toilet base to bowl seam from the outside and expect a miracle. It won't happen !!!!!

If you consider replacing with a 320 toilet, remember that the toilet is about 2" longer behind the top rim, so if you have limited space between the rear of the toilet and the wall behind the toilet, you'll have problems getting the toilet to fit. If you have more than 3 or 4 inches between the top of the rear of the toilet and the wall, you should have enough clearance to install a 320 model. If not, I'd "hedge my bets" on just getting another 310.

It would be a "cold day at the equator" before I ever considered a Thetford product over a Dometic product. IMO, even the "plastic bowl, lightweight 300 with all its leaking problems" is head and shoulders better than the best Thetford toilet. I've had both, cussed only the Thetfords, so ......

[sourdough]

Originally Posted by Scott in Michigan

All,

I appreciate the replies.* Our unit is a 2018 Cougar 32RLI.
*
After a MICH to ARIZ trip last year (I blame New Mexico's roads) it showed up for us.* Inspection showed liquid at the pedestal to bowl junction.* The tiniest amount would then seep down over the pedestal and collect at the floor.**Turns out the 310 leak was well known.* Of*course, it's not the kind of thing you search*for if you aren't experiencing*it.**

I caulked the bowl/pedestal seam as a stop gap.* A deeper internet search today also showed complaints regarding the 320 leaking from the pedestal to bowl seam.* There apparently*is no difference in their internal design*at this seam.

From your comments, I acknowledge it never shows up for some of us.* Maybe it visits us who log miles on the rougher roadways, quicker?* NM roads were a lot better this year, BTW.

Sounds like the Thetford is not a good replacement choice. *

Does that super water proof tape they hawk on TV really work??**

Does anyone have a tested recommendation for caulk for wet applications? *

Scott

IMO you're not going to find an RV toilet better than a Dometic 310/320, certainly not a Thetford and I've not talked to anyone that had a Dometic with a "design flaw". I've driven lots of NM roads, and even worse highways/interstates in LA, and never had an issue with any of the 310s I've put in. It sounds like you must have gotten the "odd one".

If it were me I'd just replace it with another either 310 or 320 (if the wife approves) and go on down the road, they have enough excellent history that I wouldn't worry at all. I wouldn't be trying to seal the leak up with caulk or tape of some kind....there's still a leak and it's going to go somewhere.

[Pull Toy]

Domestic had a recall for that problem some time ago on their 300 series toilet. I would call customer service before making any changes. You might be entitled to an adjustment or replacement.

We went to the 320 with soft close wooden seat, and never looked back, but check your measurements carefully.

[wiredgeorge]

Originally Posted by Pull Toy

Domestic had a recall for that problem some time ago on their 300 series toilet. I would call customer service before making any changes. You might be entitled to an adjustment or replacement.

We went to the 320 with soft close wooden seat, and never looked back, but check your measurements carefully.

The recall was for that little plastic filler part that screws onto the back. They can leak. I had mine leak in a previous camper and they wouldn't replace it under the recall as my 300 series (310 as I recall) was well out of warranty period and I had bought the camper 2nd hand. I paid about $25 for a new one, put it in and never had another problem. Back then, they were replacing the whole toilet if memory serves.

[BruceinDFW]

I had a Thetford Aqua Style II in our 2017 3811MS - and fought with it for a couple of years. I replaced it in May 2022 with a Dometic 320 - just before heading out for a three-month summer trip. The Dometic 320 didn't give us any issues - other than not having enough water flow toward the front of the elongated bowl to always get TP on the first flush. I'm guessing that - had I purchased a new Thetford of the same type, it probably would have been fine also, but I couldn't chance it since we were heading out soon.