Thetford Toilet Installation Instructions

Updated February 21, 2017

Thetford is an American company that began manufacturing and selling sewage holding tanks and toilets for mobile homes and recreational vehicles in early 1960s. Thetford toilets are made of lightweight materials and use very little water compared to standard toilets in the home. This keeps the vehicle weight down and conserves water from the limited supply in the RV storage tank. A new Thetford toilet installed in your RV should give many years of service.

Turn off the water supply to the existing toilet by turning the water shut off valve at the base of the toilet in a clockwise direction. Loosen the fitting on the water supply pipe to the toilet with an adjustable wrench in a counterclockwise direction.

Press in on each side of the plastic shroud at the base of the front of the toilet, then pull the shroud forward and away from the toilet. Skip this step if the existing toilet does not have a shroud.

Remove the retaining bolts from each side of the toilet with an adjustable wrench. Lift up on the toilet to release it from the toilet flange seal and then remove the toilet and place it aside.

Scrape off any remaining flange gasket material from the floor with a putty knife. Push a new flange seal into the base of the new Thetford toilet until it is fully seated.

Place the toilet into position on the floor. Trace around the base of the toilet onto the carpet on the floor with a felt-tipped pen. Set the toilet aside and cut away the excess carpet on the line pen marks with a utility knife. Remove the excess carpet. Skip this step if the bathroom does not have carpet.

Place the Thetford toilet over the mounting area on the floor. Press down on the toilet using your body weight to compress the toilet flange seal. Replace the toilet retaining bolts and tighten them.

Replace the water supply line to the new toilet and tighten the fitting. Turn on the water supply.


Do not over-tighten the toilet retaining bolts or the toilet, which is made from plastic, could crack or be damaged.

Things You'll Need

  • Adjustable wrench
  • Putty knife
  • Felt tipped pen (optional)
  • Utility knife (optional)
  • Toilet flange seal
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