Installing a Cassette Toilet

A toilet is a necessity in any home including campers and RVs. Our Palomino Bronco 1500 came with a shower/toilet combo. This sat on top of a small seven-gallon black water tank. This is fine for the weekend warrior, but when it comes to a life of full-time travel it was less than ideal. Seven-gallons isn’t a lot of space and black-water dump sites can be hard to find in remote locations. I also just didn’t care for the idea of lining up for my turn to use a dump site. So, I started looking at alternatives and that is when I found the Thetford C223-CS. I was sold on the Thetford cassette toilet system as soon as I read about it and started making a plan for installing a cassette toilet in our truck camper.

How it works

The cassette toilet is convenient. It looks like any other toilet and has a water flush system. Where it is different is that it sits over a removable cartridge which is called a cassette. This cartridge can be easily removed from the camper or RV and emptied anywhere that has a toilet. F

The Renovation

The toilet/shower area before the renovation.
Our toilet/shower area prior to installing a cassette toilet.

The original toilet/shower setup was cramped and I couldn’t imagine actually taking a shower in there. If we had used the shower, the water would have emptied straight out the back of the camper as the unit didn’t have a grey water tank. Plus, a few short showers would nearly empty our 24-gallon fresh water supply. The camper also has an outdoor shower so if we really need it we can use that one. So, we opted for removing the interior shower to free up some space for other renovations (primarily that grey tank… another post to come).

Removing the Blackwater Plumbing and Sealing

A roof patch.
I used a drywall protection disk (doorknob wall protector) that I screwed into the roof followed by a lot of ProFlex RV to patch the hole from the old blackwater vent pipe.

As a part of removing the factory installed shower/toilet combo, we had to remove the shower door, faucets, toilet, the shower base, the raised floor, and all the plumbing. This included removing the blackwater vent pipe that ran to the roof. I used a plastic doorknob wall protector from Lowe’s to cap the hole left on the roof and made sure it was well sealed with ProFlex RV. I also had to remove all the shower and blackwater plumbing underneath the raised floor along with the release valves on the bottom of the camper. This meant more holes that needed patching underneath the camper. Here I used some plywood pieces and polyurethane to weather seal it. Once again using the ProFlex to seal the edges of the boards to the camper.

The raised plywood floor under the shower basin.
The raised particle board floor that held the shower basin was difficult to remove as it was nailed to the 2×4 supports. I cut chunks of it out with the jig saw allowing access to the screws that attached the 2×4’s to the floor.

Removing the plumbing and black tank was a nasty job, but really the worst of it was when I removed the raised floor under the shower/toilet and found hundreds of dead flies. They must have come in through the gaps between the plumbing pipes and the floor. Palomino should probably seal these openings to keep the critters out. The camper lost a lot of weight by removing the dead biomass.

Re-engineering the Wall

Cassette toilet in place with a new wall and curtain.
I adjusted the wall so that the toilet area is more comfortable utilizing the space in front of the door.

Once everything was removed I had to cut away a piece of the wall that was a part of this area and re-engineer it. I wanted more space for the toilet area. We designed the layout to use the entrance area of the camper as an extension of the restroom. This effectively makes the area larger and more comfortable. We use a curtain that is easily moved to close off the area when in use. The curtain covers up the toilet area when not in use. It works well with just a few pieces of velcro needed in specific spots.

The biggest challenge of re-engineering the wall was getting that plastic endcap/wall protector strip sourced. I looked all over the internet with no luck but eventually found it at my local Camper World.

Widening the Bathroom Storage Door

The bathroom area's storage access door.
As a result of removing the raised floor the cassette toilet sits lower. This allowed us to increase the size of the access door to the storage area behind. This makes this area much more useable.

I also took this opportunity to widen the existing door for the storage in the bathroom area. The existing door was small because of how high the old toilet set due to the black water tank and plumbing underneath.

After cleaning up the area with the new cabinet door, a new wall section, and a few accent panels it was time to start installing a cassette toilet.

Dealing with Thetford

The day after I ordered my Thetford C223-CS Cassette Toilet I was contacted letting me know the toilet would be delayed for a month. Thetford had just released an update to the model and they were on back order. Luckily, it didn’t take a month, but it did take a few weeks. This gave me ample time for the renovations above so that when the toilet arrived I was ready to start the install.

Another Thetford Wait

The Thetford cassette access door. Part #32144
The lockable access hatch is sold separately from the cassette toilet.

Once it did arrive my unit didn’t have any directions for installation. I contacted Thetford and they apologized and emailed me the PDF. The next issue was that I didn’t realize that the toilet didn’t come with the access door hatch that mounts in the side wall. This makes no sense to me. Once the toilet is installed the only way to access and remove the cassette is if you have the door. So, I had to wait another week while the $70 plastic access door (part #32144) arrived before continuing with the install.

Thetford seems like a great RV-minded company, but I don’t understand why they sell the access door separate from the toilet. I can’t imagine how someone would use this toilet without the access door.

The 4-Blade Connector

The last issue I have with Thetford is that the toilet comes with a 4-blade electrical connection. This would be okay if they shipped the product with the female 4 blade connection, but they don’t and I couldn’t find the part locally. I eventually used single female blade connectors to attach the wiring. Another good option would have been to cut the connector off and splice the wires together.

Installing a Thetford C223-CS Cassette Toilet

Truck Camper Renovation
Safety first when working with power tools.

Installing a Thetford C223-CS is intimidating. It takes some patience and ability to use basic power tools but it isn’t terribly difficult. The Thetford access door (part #32144) actually comes with a lot of templates that makes getting the placement of the door very easy despite the instructions being pretty vague. The door piece can be mounted in one of four orientations. This allows the door itself to swing in any direction of your choosing. This decision needs to be made before the first hole is drilled in the camper’s wall.

Make Sure the Door Cut is Just Right

The Thetford Cassette being slide out of the access door.
If you don’t get the door mounted correctly, the cassette might not slide in and out easily.

Make sure that where the door finally lands is high enough off the interior floor to allow for the bits of plastic that the cassette sits on. If you are too low or too high it could make removing the cassette difficult and if way off impossible. For me, this meant that the lower pilot hole for the first template was 1 3/4″ above the inside floor and 14 11/16″ to the second pilot hole.

Using the Templates

Palomino Bronco 1500 wall taped up and ready to be cut through.
Using tape to reinforce the area that will be cut out reduces the blades tendency to rip the material. This will ensure a cleaner cut.

The first template goes on the inside where the back of the toilet meets the wall. I drilled the pilot holes through the outer wall showing me where to put the second template on the outside of the camper. I screwed down the outside template and tapped off the area well on both sides of the wall. The tape helps to prevent the ripping of the wall as the jigsaw blade passes through. I then traced the template onto the tape using a Sharpie and proceeded to drill starter holes through two of the corners. These holes are where I was able to start the jigsaw and cut out the rest of the traced template. Be careful not to use a drill bit that is too large for your starter holes as a certain amount of this cut piece is needed to fill in the access door.

Reinforcing the Edges

After the piece was out I removed the tape. Next, I removed some of the foam insulation from the edges of the cut. I removed the foam to a depth of about 3/4 of an inch. I achieved this by making small horizontal slices with a razor blade about 1/2″ apart followed by a flat head screwdriver to pop the pieces out. This method works surprisingly well to get a fairly even depth. I then cut small pieces of 1 x 3 pine boards to the ideal depth of a 1 x 1 (really 3/4″ x 3/4″), and used these pieces to reinforce the edges of the wall. I used liquid nails to make sure that these pieces would stay in place.

Cutting the Door Piece to Shape

I took the piece of the camper wall that was removed and placed the 3rd template on top. Before tracing the template onto it, I made sure the edges of the template landed on as many reinforced sections as possible. This minimizes the amount of reinforcing needed to make this a solid piece before placing it into the door frame. After tracing the template and using tape to make sure I got a clean cut, I cut the piece to shape with my jigsaw. Once I removed some foam insulation and reinforced this piece as needed with 1 x 1’s, I was ready to install it in the plastic frame that Thetford provided.

Putting the Pieces of the Door Together

Once the 3rd piece is cut out it easily slides into the plastic molding provided by Thetford. It is latched into place with little metal brackets hammered onto the edge of the back plate. I used ProFlex here as well to make sure that this door piece was weather sealed. Make sure that the piece is set inside the door so that the weatherproofed side ends up on the outside of the camper. You will need a mallet to sandwich all these pieces together.

Mounting the Door on the Camper/RV

The door is now ready to be placed in the hole cut earlier in the camper wall and screwed into place. Remember that the door can be placed in one of four orientations so make sure you have your desired orientation before mounting it. I placed my door so that the door opens to the right. To make sure it was watertight, I put a bead of ProFlex RV on all the edges. Be careful not to get sealant in the door hinge. Predrill the mounting holes first will prevent woodchips and other particles from ending up in the sealant.

Once the piece on the outside is in place the last piece fits on the inside of the camper to cover the hole. This piece attaches with 4 small screws.

Mounting the Thetford C223-CS Cassette Toilet

Now that the door is in place it is a simple task to mount the hook on the inside of the camper which latches the top of the toilet to the wall. From there I screwed down the bottom of the toilet via the 4 screw holes on the inside of the cassette’s holding area. This must be done from the outside of the camper using the access door.

Connecting the Water Lines

The cassette holding area of the Thetford C223-CS toilet.
The Thetford Cassette toilet comes with a mounted 1/2″ water hose with no fitting. I got a brass barb and some 1/2″ tube to make the connection to the exsisting plumbing.

Once the toilet was secure, I used a barb connector and a new section of hose I bought at Lowes to connect the existing water line to the toilet’s water line. I actually tried to find an RV water hose at a dealer and the person who worked there was nice enough to tell me to just use some waterline from Lowe’s because it was easier to source and far cheaper.

Connecting the Electrical Wiring

The last step was hooking up the electrical which can be a bit confusing if you have a high-pressure pump. If your pump has more than 8 bars of pressure you will need a regulator for which the toilet has two electrical control lines (purple & grey). My pump doesn’t have that kind of pressure so I only ended up needing the positive and negative lines (red & black). I ran lines from my fuse box and then used a female blade connector on each to attach them to the Thetford supplied connector. It was easy enough to wire up especially after having redone all the wiring in our camper for the solar system.


As installs go the install of the toilet was a moderate undertaking. Thetford has some good designs and the access door comes with nice templates. However, they could provide better directions on how to use the templates. The hardest part about this renovation is getting the nerve to cut through the outer wall of the camper. Had it been one of those $30,000 campers I think I would have been hard-pressed to do it. Since we bought ours used it was a bit easier.

Review of the Thetford C223-CS Cassette Toilet

The Thedford Cassette Toilet Installation and renovation completed.
The area after the cassette toilet renovation.

I really prefer the flexibility that the Thetford C223-CS cassette toilet gives us when it comes to emptying our full-time camper/home of its black water. At a capacity of 4.75 gallons the cassette toilet’s holding tank may seem small, but given that it can be emptied almost anywhere it is a perfect size for a life on the road. For more information on our thoughts about this cassette toilet click here.

Showering on the Road

Some of you are probably wondering where we take showers now that we have completely removed our indoor shower. Well, when remote enough we can use the factory installed outdoor shower. When we are in cities/towns our primary showering spot is Planet Fitness. Other options are campground showers, truck stops and, of course, a good box of baby wipes goes a long way as well.

If you found this Thetford cassette toilet installation helpful please share it on your social media networks. Thanks!


Needed Tools for Install:

  • Pencil
  • Drill
  • Screw gun
  • Jigsaw
  • Hearing protection
  • Eye protection
  • Shop Vaccum
  • Knife
  • Flathead screwdriver
  • Rubber Mallet
  • Aluminum or wooden trim pieces
  • Sealant

3 Comments Add yours

  1. Fantastic Job!! I am glad to read this article such an amazing article. Thank you so much for sharing

  2. Jesse says:

    Great instructions, so strange they would sell the toilet without the access door, I totally agree, thanks for sharing!
    Jesse recently posted…Why You Need a Drain CameraMy Profile

    1. NomadicMoments says:

      I hope it was helpful.

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