Complete Guide: Upgrading to a Dometic Ceramic RV Toilet with a LUXE Bidet

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While Casitas use standard 1/2″ screw-on swivel fittings at the toilet water valve, the pipe leading up to it is stiff, rigid PEX tubing. Because an upgraded ceramic toilet (like the Dometic 320) places the water valve higher up and at a slightly different angle than the stock factory toilet, that rigid PEX pipe won’t reach without putting severe strain on the new plastic valve.

Unscrewing the factory line and inserting a 20-inch flexible braided stainless steel line gives you the slack and bend radius needed to align everything stress-free.

Required Tools & Parts

⚠️ Important Sizing Warning for Amazon Buyers: Do not buy the popular “1/2” x 1/2” x 9/16”” bidet T-adapters sold across Amazon! The 9/16” side outlet is designed for handheld sprayers or import bidets and will not fit the 1/2″ supply hose included with LUXE NEO series bidets.

You must order the true LUXE 1/2″ Metal Cold Water T-Adapter directly from LUXE to ensure the top, bottom, and side ports are all 1/2″ threads.

Step 1: Remove the Old Toilet

  1. Shut off the fresh water supply: Turn off your city water connection and turn off the 12V water pump.
  2. Relieve line pressure: Step on the flush pedal until water stops flowing into the bowl.
  3. Disconnect existing water line: Place a towel under the water valve at the back of the toilet and disconnect the fresh water line.
  4. Unbolt the base: Pop off the plastic floor bolt caps and unscrew the brass nuts on both sides of the base.
  5. Remove old unit: Lift the toilet straight up and set it aside on a tarp or plastic bag.

Step 2: Prep the Floor Flange

  1. Block tank gases: Stuff an old towel or rag into the black tank drain hole to keep odors out of the camper while you work.
  2. Clean the flange: Scrape away any old rubber residue, wax, or grime from the mounting flange.
  3. Set flange height: If your floor flange sits below the level of your finished flooring, use the stacking spacers included in the MENNTY Elastic Seal Kit to bring the height flush with the floor.
  4. Install new T-bolts: Slide the new brass T-bolts into the slots on the flange so they extend straight upward.

Step 3: Install the Flexible Fresh Water Line

  1. Disconnect the original rigid PEX line fitting from your trailer’s fresh water feed pipe.
  2. Thread one end of the Eastman 20-Inch Steel-Flex Connector onto the fresh water supply pipe.
  3. Hand-tighten first, then add a 1/4-turn with a wrench. (Do not overtighten brass threads.)

Step 4: Mount the LUXE Bidet & Set the New Toilet

  1. Prepare the bidet: Place the LUXE Bidet NEO 185 on the rim of the new Dometic toilet, lining up the circular adjustment plates with the toilet seat mounting holes.
  2. Attach seat: Place your toilet seat over the bidet bracket and tighten the seat bolts firmly to hold the bidet unit in place.
  3. Remove rag: Take the towel out of the black tank drain.
  4. Place elastic seal: Set the MENNTY Elastic Seal over the flange. (Unlike wax rings, elastic seals can be adjusted without ruining the seal if you don’t drop the toilet perfectly on the first try.)
  5. Set the toilet: Lift the Dometic toilet, align the base holes with the floor T-bolts, and lower it onto the flange.
  6. Secure base: Press down firmly with your body weight to compress the seal, then install the washers and nuts onto the T-bolts. Alternately tighten each side until snug. (Caution: Over-tightening can crack ceramic or plastic flanges!)

Step 5: Plumb the Bidet & Water Supply

  1. Attach the 1/2″ T-Adapter: Thread the female swivel nut of your LUXE 1/2″ Metal T-Adapter directly onto the 1/2″ male water inlet valve on the back of the Dometic toilet. Ensure the rubber washer is seated inside, hand-tighten, and add a 1/4-turn with a wrench.
  2. Connect supply hose: Thread the top end of your Eastman 20-inch flexible line onto the bottom 1/2″ male port of the LUXE T-adapter.
  3. Connect bidet line: Thread the 1/2″ end of the small braided line that came with your LUXE Bidet to the side 1/2″ port on the T-adapter. Connect the 1/4″ end to the cold water inlet on the bidet control panel.

Step 6: Test and Finish

  1. Turn your trailer’s main water supply (or 12V pump) back on to pressurize the system.
  2. Check for leaks: Inspect all three connections on the T-adapter, the fresh water supply pipe connection, and around the base of the toilet.
  3. Test flush & spray: Step on the flush pedal to confirm proper bowl fill and drain operation. Turn the LUXE bidet dial to test water pressure and spray alignment.
  4. Snap the plastic bolt covers from the MENNTY kit over the floor bolts to finish the job.
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