Open Roads Forum

Print  |  Close

Topic: RV Toilet Floor Flange Size ??

Posted By: twocruisin on 04/28/10 09:49am

Can anyone tell me if the floor flange on an RV Toilet is the same size as a houshold toilet.......
I'm thinking of replacing the plastic RV Thetford Toilet with a Koller household toilet and tank.....
I have plenty of room in the bathroom to fit a real toilet.......On the road I would just shut of the water supply to the toilet and flush it to get the water out of the tank......
I seems like something I'd like to have, a toilet thats easy to keep clean, quiet and I would have the ability to change the toilet seat whenever I wanted to..

I'm interested to know if anyone has done a job like this and if there is a lot of work below the floor to change the floor flange that holds down the RV toilet to accept a household toilet.......If the flanges are the same size it seems like an easy switch.......

Anyone with experience ??



Crystal River
40 Foot Damon Diesel Bus

Posted By: rgatijnet1 on 04/28/10 09:57am

The floor flanges are the same but I would advise against doing this. A household toilet has a top tank lid that will rattle and break. it must be removed. A household toilet will not stop water from sloshing out as you go down the road. The bowl lip is designed for water circulation, not stopping the water from sloshing out. The tank mounts to the base with a rubber gasket. This gasket seals the connection but it does not isolate the porcelain top from the porcelain base. There is a pretty good chance that one or both may beak. The household toilet is also at least twice as heavy as the RV toilet.
Just get one of the porcelain RV toilets, made by a few manufacturers, and rest easy that it will serve you well as you bump on down the road.

Posted By: Buck62 on 04/28/10 11:44am

Household toilets are designed to use a wax ring for sealing around the "horn" of the toilet. I am not sure if you will get a proper seal with a rubber gasket. Remember if it leaks around the base you will have a major repair job replacing the sub flooring. Personally, I would not do it, RV's are not designed for household toilets.

Posted By: rgatijnet1 on 04/28/10 12:24pm

I would just use chemicals in my black tank and turn on the vent fan. If that doesn't work, I would change my diet.
I have never seen any Kohler toilets that bolt to the wall other than wall mount commercial toilets, which hang from the wall and don't touch the floor. The extra weight on the floor from a standard floor mount toilet, and the base being held with only two bolts, might not be enough to keep the flange from breaking at the base as things flex going down the highway.

Posted By: Dutch_12078 on 04/28/10 10:09am

I agree with Ron, this seems like a bad idea in a moving vehicle. There are several porcelain bowl RV toilets that use a standard toilet seat, such as Thetford's Aqua Magic Style PLus, that would be much better choices.

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

Posted By: twocruisin on 04/28/10 11:25am

I've had a porcelain Theford toilet and didn't like it.....Even when they are brand new you get a smell in the house when you flush the toilet.....A house toilet has a built in P trap that keeps that from happening....Also, a two gallon flush would keep the black water tank working better because of the extra water going down with each flush....

I can attact the tank to the rear wall with lag bolts to hold the extra weight.....I know they already have holes to do so....I have a false wall behind my RV Toilet now that we store toilet paper and I have an automatic fan that vents the room to the outside with a dryer vent.....That's also in the false wall.....

On the road I would shut the water off, flush out the water from the bowl and put the lid down inside my false wall.......When we get where we want to be it would be easy to reverse the process....

As long as I don't have a lot of fooling around with getting the floor flange to fit and put it a wax seal instead of rubber, I think it would be fine for me.......

The extra weight wouldn't mean anything if the tank is secured to the false wall.....



Posted By: phnguyk on 04/28/10 05:36pm

Hi, our 98 class C was retro fitted with a house toilet. I personaly miss it. It was a one piece tank and bowl. The pevious owner put some thin rubber weather stripping on the tank and you couldn't hear it rattle. Never leaked, didn't do anything special while on the road other that flush it. Come to think of it he may have reinforced the floor with a 3/4 thick square piece of plywood and linoleumed it and some quarte round. Never wobbled, never leaked. It was made by American standard cp-2032. Good luck, I've been thinking of changing ours.

Posted By: Suescasa Mycasa on 04/28/10 06:08pm

I feel big mistake
I think with all the water motion the trap will probably flush itself
I cant even imagine the water in the tank sloshing over top
Also too much water wasted
Other than that ..........

2003 Travel Supreme Select 45'
ISM 500 Oh Myyyyyyyyyy
2003 Yamaha V Star 1100
Joeylift motorcycle lift
rollin rollin rollin... keep those doggies rollin

Posted By: ChaosAgent on 04/28/10 06:01pm

Ron8877 wrote:

All of the rv toilets I have seen have the bolt holes in the front and the back of the toilet not on the sides like a household toilet has.....

That doesn't seem to be true any more with the new RV toilets. Last month I replaced my 1999 model Sealand Traveler 510 toilet with a brand new one of the same make and model, thinking the new one would just drop into place. WRONG!

The new toilets now have the standard two hole mount instead of the old four hole one.

Had to drill out the old flange to get the new toilet to fit.

'99 American Eagle 40NS 'Beauty'
'04 Dodge Dakota 4x4 Crew Cab Toad
Karma Karma, The Coach Cat
Our RV Adventures

Posted By: Dutch_12078 on 04/28/10 02:35pm

It occurs to me, regarding the P-trap, that anyone that has tried to move a toilet with water still in the trap has found out how little it takes, no matter how hard you try to keep it level, before water starts running out on your shoes and floor. I'd not be surprised to find that you'll have even more smell issues with a conventional residential toilet than you have with your RV toilet.


Posted By: MAJESTYPOINTERS on 04/28/10 01:34pm

To answer your question....without questioning your reason......I replaced my toilet with a new RV fixture......The RV flange on mine was different than I have seen in a house but the "PIPE" was the same (PVC) as used in a stick house so It should be easy for you to change the floor flange.....P.S. Lowes even sell a "WAXLESS" toilet flange so the vibrating should not affect the seal at the floor....Individuality makes the world interesting

Posted By: Ron8877 on 04/28/10 01:59pm

All of the rv toilets I have seen have the bolt holes in the front and the back of the toilet not on the sides like a household toilet has. That being said there is a red ring that you can get from the store that is a toilet flange repair ring you could screw this to the floor and then bolt the toilet to this. The wax ring would work although I would recommend a wax ring with horn. If the bathroom floor is strong enough to hold you I don't see where the weight of the toilet would be a problem. If you have the 12 inches from the center of the flange to the back wall it should fit. If you don't have 12 inches there is also a 10 inch rough-in toilet that you can get. The only thing that bolting the toilet to the back wall will do is to help prevent the toilet from moving, it won't help hold any of the weight. If you shut off the water to the toilet for moving and then flush the water out of the tank you would still want to get most of the water out of the bowl before you drive off. One way to do this would be to dump about 2-3 gallons of water down the toilet from a bucket this would drain the bowl and then just put enough water in the bowl to fill the trap. If you decide to do this then you can buy any residential toilet to put in the rv. Good luck.

Ron & Ali Workentin

Posted By: rgatijnet1 on 04/28/10 02:07pm

The weight of the toilet is only a problem when it starts moving and bouncing going down the road. More weight means more momentum which means more stress on two small bolts fastened into 1/2" flakeboard or plywood. The toilet will also be more top heavy than the RV toilet which will increase the strain on those two little bolts.

Posted By: Dutch_12078 on 04/28/10 01:01pm

twocruisin wrote:

I've had a porcelain Theford toilet and didn't like it.....Even when they are brand new you get a smell in the house when you flush the toilet.....A house toilet has a built in P trap that keeps that from happening....Also, a two gallon flush would keep the black water tank working better because of the extra water going down with each flush....

We don't get any smells in the house when we flush our Style Plus, John. We do have a 360 Siphon Vent on the vent line on the roof though, and we always make sure the bathroom fan is turned off before flushing.


Posted By: twocruisin on 04/28/10 06:41pm

I've read all the posts.........

The weight isn't a factor...Bolting the tank to the rear wall would prevent the whole toilet from moving....A modern houshold toilet probably uses about the same water as an RV toilet......I know I could get the floor flange to work out with a wax ring and collar somehow........BUT...

The biggest problem is the fact that after flushing the water out of the tank and bowl before moving the chances are pretty high that the P trap would empty itself........My bus is on air bags so there's really no bouncing around, but just a little front to back or side to side motion would make the P trap empty out quickly.....

The P trap problem letting odors into the room when it empties with motion can't be avoided and I would have a direct path from the holding tank to the room.....BAD IDEA....

I guess the only way to go is with a good RV Toilet.......

Thanks for all the feedback.....Without batting the idea around in this forum for a day or so I probably would have made a big mistake in the long run....That's the best part of being a member here......



* This post was edited 04/28/10 06:48pm by twocruisin *

Print  |  Close