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Are there any RV toilets with a P trap?

btrippy
Explorer
Explorer
I'm getting tired of trying different black tank deodorizing solutions.. I can't seem to find one that knocks out the odors as well as breaks the junk down. I've tried at least 4 different products, and while most work for a few days, they never last the whole tank.

My question is, are there any RV toilets that have a standard house P trap in them? I'm guessing that would eliminate the smells and allow the use of any black tank solution.

I'm all ears for any additional solutions as well.

Thanks!
22 REPLIES 22

JimM68
Explorer
Explorer
Our Monaco motorhome has a techma by thetford macerating toilet.
It does indeed have a true P trap.
It also grinds waste to liquid. We use real 2 ply TP without a problem.
Nothing comes out beside brown water when we dump.
Jim M.
2008 Monaco Knight 40skq, moho #2
The "68"
My very own new forumfirstgens.com

My new blog

3_dog_nights
Explorer
Explorer
Have never had a problem since I started using these. Been rv'ing for 40 years.

click - toilet tab's
Bob & Lynn
2 Chihuahua's, Ella, Gracie

was-2013 Open Range 424RLS,06' Chevy 3500, dually, Duramax/Allison

also was - 2015 Winnebago Adventurer 37F, towing 2003 Jeep Wrangler

now - 2021 NoBo 19.5, 2019 Honda Ridgeline RTL (Talk about downsizing!)

TXiceman
Explorer II
Explorer II
Dutch_12078 wrote:
One little tip that will cut down on black tank odors is to make sure the bathroom vent fan is turned OFF before flushing.


You would be surprised at the number of RVers that do not know or do this.

Ken
Amateur Radio Operator.
2023 Cougar 22MLS, toted with a 2022, F150, 3.5L EcoBoost, Crewcab, Max Tow, FORMER Full Time RVer. Travel with a standard schnauzer and a Timneh African Gray parrot

jims1
Explorer
Explorer
A Tecma Easy Fit has a similar bowl and exit system as a house style commode, but it's hooked to a macerator pump. I've installed or had installed a hundred or so when I was in the custom boat business
Volvo dually Pickup
DRV Memphis
Me, Alie, and Salie
Fulltiming

CarlGeo
Explorer
Explorer
nomad297 wrote:
Turbo Diesel Dude wrote:
Toilets DON'T have "P traps" The water on top of the valve keeps the smell in. Only drains have the traps. That's why your household commode has the water I it. JMHO


It's not the water that keeps the smell in on an RV toilet. It is the seal on the valve that does that. Water standing in the RV toilet is only there because the rubber seal won't allow it to go by. Residential toilets do have traps -- just not p-traps -- they are s-traps.

I don't know of any RV toilets with traps.

Bruce

You state correctly that residential toilets do not have P traps, but S trap built into the toilet itself. The standing water in the toilet is the seal.
RV toilets have a rubber seal around the valve that keeps water in the toilet bowl, and that standing water is the vapor seal. Should the seal not hold water, you will have no vapor seal and you will get sewer gas into the coach.

btrippy
Explorer
Explorer
Many thanks for the MANY responses! I'll check the simple things like the vent and move to other items. Maybe my seal is bad or something as well.

In any case, thanks for the overwhelming responses!

Old-Biscuit
Explorer III
Explorer III
Something YOU didn't really explain.......

When do you have this odor?
Just when you flush toilet-------or----all the time?

All the time
You have an issue with toilet. Either bowl seal is not holding water (vapor barrier), floor flange seal is bad (mechanical barrier) OR toilet/toilet area needs cleaning (floor/walls----under toilet rim/beneath shroud etc)
OR black tank vent line is cracked

OR smell is not from black tank but from grey tank and is coming up thru 'air admittance valve' located on bathroom sink drain line after the 'p' traps.
Allows air in when drain grey tank so 'p' traps don't get sucked dry...then closes when not draining. If worn out they don't close..grey tank can smell as bad as black tank. Just screw on to a stub pipe by and...replacement at any hardware store

When you flush
Do you have exhaust fan running (it will pull odors up thru toilet)
Fan off..but still smell it when flushing (light a kitchen match afterwards)
Is it time for your medication or mine?


2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31

Dr_Quick
Explorer II
Explorer II
This has worked for me. Whenever tank it empty, we fill the toilet bowl with water to the top four times and dump. If solids are going into the toilet when it is used, first fill the bowel about 1/2 way with water. After flushing, if there is any residue in bowel add a bit of water to cover. Next time you flush toilet bowl it should be clean. Never have had an odor problem, and I never use an additive.
Dr Quick

kayakcrazy
Explorer
Explorer
We installed one of these and it seems to help.

http://www.campingworld.ca/shopping/item/cyclone-sewer-vent/31992

C-Bears
Explorer
Explorer
Can't really add to much that has been suggested. I would check toilet roof vent first to make sure it is not blocked and operational. We use additive after dumping our black tank, plus I add about 4 or 5 gallons of water to the empty black tank. On each flush we use a lot of water.

When dumping the black tank we do a lot of rinsing.

If you still can't control smells, and you are sure they are coming from black tank, you may want to check for a split in the tank. Can you detect a black tank odor from outside or under your unit?
2014 Montana 3725RL (Goodyear G614 Tires, Flow Thru TPMS)

SPENDING THE WINTERS AT OUR HOME IN SW FLORIDA. THE REST OF THE YEAR SEEING THE U.S. FROM OUR LIVING ROOM WINDOW!

the_bear_II
Explorer
Explorer
In 50 years of RVing the only time we have experienced odors from the black tank is when something is wrong... black tank roof vent blocked, gasket between the toilet and flange is bad or seal at the flap is bad. Once the problems were fixed no more smell.

We have always used Thetford Aqua Kem. It is a deoderizer plus has enzymes to break up the gunk.

Another tip is to use more water to flush. Fill the bowl half full before flushing.

edbehnke
Explorer
Explorer
replace toilet with a dometic 320. anyway, you shouldn't be having this issue if you are vented correctly. never had an issue with our toilets. the seal on the toilet holds a little water to stop the smell from coming up from the tank.

if you smell something as bad as you say then there is something else going one.
eddie and sandie
3402 Montana 2013
Ford F350 2015

korbe
Explorer
Explorer
Newer RV's have been designed to minimize odors coming up thru the toilet while flushing. Older RV's not so much. If you have a newer RV, the odor problem may be because of the vent not working properly. JMO
.

Dutch_12078
Explorer II
Explorer II
One little tip that will cut down on black tank odors is to make sure the bathroom vent fan is turned OFF before flushing.
Dutch
2001 GBM Landau 34' Class A
F53 chassis, Triton V10, TST TPMS
Bigfoot Automatic Leveling System
2011 Toyota RAV4 4WD/Remco pump
ReadyBrute Elite tow bar/Blue Ox baseplate