Removing the toilet, replacing with PortaPotti

[Brittany Dogs]

I was hesitant about clicking on the "watch product video" hyperlink. So glad they warned you to not use it while the vehicle is in motion.

People have mentioned the difficulty of reaching the slide tabs that lock a Thetford unit to the floor flange. I finally decided to trash ours for a porta potti, and began to take the diabolical toilet apart.

After several attempts to reach the lock slides with various hooks and such, I noticed that there was a stainless screw at the lower front corner of the toilet. When I removed it the bottom skirt on that side came off and the entire slide and lock assembly could be seen. A right-angle screwdriver was needed to remove the screw on the shower side, but it was then a simple task to pull the lock slides out with a small screwdriver.

There may be variations in the toilet models, but this was the setup on our 2007 TM 3326. Taking off the skirts makes the removal much easier.

I finished the porta potti install today, and found a potential plumbing problem for those who have or may intend to replace their Thetford toilet. I will say my unit is a 2007 TM 3326, there may be differences in the assembly from year to year.

Prior to putting down the new false floor supports, I went under the trailer to look for any problems or obstructions. When my arm brushed the black/gray water piping assembly under the trailer, I realized it was loose and could be moved around and particularly up and down a bit.

Things that make you go hmm...

After some investigation, I discovered that the three inch black water discharge pipe is connected to a bowl-shaped coupling that sits inside a corresponding curved seat on the floor flange. I suppose the intent is to permit a bit of movement of the pipe when connecting the toilet. The floor flange is then mated to the slide valve and above that the main toilet, and everything is bolted together making a rigid seal.

When you take the toilet and slide valve away, all you are left with is the bowl coupling sitting in the floor flange and held there by gravity. As I moved the piping around under the trailer I realized the only other connection point is where the gray water connects to its storage tank, and I could see that connection flexing as the whole thing moved. Not a good idea in my mind.

I decided to make my porta potti floor out of plastic composite board you can find at local home improvement stores. Mine was an eight foot plank which was 11.25 inches wide, used for deck trim. I needed something to create a downward pressure on the flor flange, so I cut two pieces of the board nine inches long and two inches wide, and screwed them down onto the floor flange between the mounting bolts. This tightened up the piping assembly and took away the potential for movement. If this flange is not secured in some way, I can see eventual up and down movement during travel creating pipe stresses that might lead to failure. This only occurs if you take out the old toilet.

Members who have removed their Thetfords may wish to see if they have any movement of the black piping exiting the floor of the trailer. There are a number of ways to fix it, I used the strapping method because I still had access to the the flange before putting down the floor.

I have attached a photo showing how I screwed the strapping across the floor flange. The other gray pieces are built up blocks that I used for vertical spacing, with the top floor panels screwed into them. The result was a nice rigid floor when I was done. I added a couple of blocks in the back to keep the potti away from the wall, a vertical piece at the front with a two inch fiddle to keep the potti from sliding off, and I added a stainless eye bolt on each side that I can use for a bungee or rope to secure the toilet when traveling. The end result should be much more pleasant for us than the old stinkpot.