How to Remove the Pedal on a Thetford Aqua-Magic Style II or Residence Toilet (and Replace the Water Valve or Drive Arm)

Posted by Dave on Nov 10th 2026

How to Remove the Pedal on a Thetford Aqua-Magic Style II or Residence Toilet (and Replace the Water Valve or Drive Arm)

"How do I get the pedal off?" is one of the questions we hear most about the Thetford Aqua-Magic Style II and Aqua-Magic Residence. The good news: the pedal has no screws or clips. It snaps onto a pivot and pulls straight off. This guide walks you through removing the pedal, then replacing either the water valve or the waste ball drive arm, the two repairs that need the pedal out of the way.

Skip to: Remove the pedal | Replace the water valve | Replace the drive arm | Parts

Which repair do you need?

What's happening Likely fix
Water keeps running into the bowl, drips from the back, or the flush is weak 42049 Water Valve Kit
Pedal moves but the waste ball doesn't open or close fully, or the bowl won't hold water 42209 Waste Ball & Drive Arm Kit
Pedal is cracked, broken or won't stay on Replacement pedal (42067, 42068, 42078 or 42079)

Watch it first

Thetford's short video shows the pedal coming off and snapping back on. It's worth a look before you start.

Tools you'll need

  • Phillips and flat-blade screwdrivers
  • 1/2" wrench (closet flange nuts)
  • Pliers and needle-nose pliers
  • 3/8" socket and wrench (drive arm job)
  • Silicone-based lubricant (drive arm job)
  • Towels, a large plastic trash bag, gloves and eye protection

Before you start: rinse and drain the black tank, then add a holding tank treatment to keep odors down while the toilet is off the floor. Wear gloves and eye protection, and disinfect your tools and work area when you're done.

Step 1: Take the toilet off the floor

Thetford's instructions have you remove the toilet for these repairs. If you have plenty of room around the toilet you may be able to work in place, but most people find it far easier with the toilet on its side.

  1. Turn off the RV's water supply (pump off, city water disconnected) and flush to empty the bowl.
  2. Lay a towel behind the toilet under the water connection, then unscrew the water supply line from the toilet.
  3. Pop off the bolt caps and remove the two closet flange nuts with a 1/2" wrench.
  4. Lift the toilet onto the trash bag and stuff a rag in the floor opening to block odors.
  5. Scrape off the old closet flange seal. You'll install a new one when the toilet goes back (one is included in both the water valve kit and the drive arm kit).

Step 2: Remove the pedal

  1. Lay the toilet on its side with the pedal facing up.
  2. Hold the toilet steady, grip the underside of the pedal at the front, and pull it straight up and off with one quick motion.

That's it: there are no screws or clips. The pedal is a firm snap fit, so a confident pull works better than slow prying. Keep track of the pedal return spring, because you'll need to hook it back in when the pedal goes on.

Option A: Replace the water valve

You'll need the Thetford 42049 Water Valve Kit. It includes a new valve cartridge, water inlet seal and spring, drive arm seal, spring retainer and a closet flange seal.

  1. Unlock the retainer. Find the water valve cartridge retainer behind the pedal. Put your thumb in the depression and your index finger under its tab, lift the tab slightly, and rotate the retainer clockwise until it stops against the spring.
  2. Pull the old valve. Slide the valve assembly out and discard it.
  3. Remove the inlet seal and spring. Use needle-nose pliers to pull the old water inlet seal and compression spring out of the water inlet opening.
  4. Install the new inlet seal assembly into the water inlet opening.
  5. Install the new cartridge. Push it in until it's fully seated, then rotate the retainer back until the tab locks.
  6. Set the valve drive pin to the closed position before you put the pedal back on.

Then go to Step 3 to reinstall the pedal.

Option B: Replace the waste ball drive arm

You'll need the Thetford 42209 Waste Ball & Drive Arm Kit. It includes a new waste ball with its "U" cup seal, the drive arm with its screw and pin, a waste ball seal and a closet flange seal. Since the bowl comes off for this job, you're replacing the whole flush mechanism at once.

  1. Remove the old drive arm. With the pedal off, remove the drive arm screw and pull out the old drive arm.
  2. Take the bowl off the base. Stand the toilet upright, remove the two bowl screws, turn the bowl counter-clockwise and lift it off the base.
  3. Remove the old waste ball. Lift out the old waste ball seal and the seal retainer. Squeeze the ends of the old waste ball together and pull it out of the base.
  4. Install the new waste ball. Position it with the "U" cup seal toward the back of the toilet, with the open, tapered side of the seal facing the ball. Squeeze the ends together, insert it into the base, and seat it in the closed position.
  5. Install the new drive arm. Insert it into the base and rotate until its keyway engages the key on the waste ball. Secure it with the new screw, then rotate the drive arm until the waste ball is in the up position.
  6. Reinstall the pedal (see Step 3) and press it a few times to confirm the waste ball opens and closes fully before the bowl goes back on.
  7. Reinstall the seal and bowl. Set the seal retainer in place O-ring side down, then the new waste ball seal flat side down. Put a light coat of silicone lubricant on the underside of the bowl where it meets the seal. Set the bowl on the base, turn it clockwise to line up the holes, check that it's centered over the waste ball, and reinstall the two bowl screws. Don't overtighten.

Step 3: Snap the pedal back on

  1. Line the pedal up on the pedal pivot.
  2. Hook the pedal return spring tab into its pocket on the pedal.
  3. Rotate the pedal slightly until the drive arm pin lines up with its pocket.
  4. Hold the pedal down and firmly press the button on the outside of the pedal until it snaps into place.
  5. Stand the toilet up and press the pedal several times. The waste ball should open and close fully every time.

Pedal won't snap on? It's almost always alignment. Pull it off, recheck that the spring tab is in its pocket and the drive arm pin is lined up, and try again.

Step 4: Reinstall the toilet and test

  1. Fit the new closet flange seal into the bottom of the toilet base.
  2. Remove the rag from the floor opening, set the toilet over the closet bolts, and tighten the two nuts just until the toilet no longer rocks. Don't overtighten.
  3. Reconnect the water supply line by hand first so it doesn't cross-thread, then snug it up. Replace the bolt caps.
  4. Turn the water back on, flush several times, and check every connection for leaks.

Parts for the Style II and Residence

All Style II parts All Residence parts

Repair or replace?

If the base is cracked, or you're on your second or third round of valve and seal repairs, a new toilet may be the better buy. See our Aqua-Magic Style II and Aqua-Magic Residence toilets, or read How Hard Is It to Replace an RV Toilet?

Not sure you have a Style II or Residence?

Steps are based on Thetford's official service instructions for the water valve kit, waste ball and drive arm kit and pedal kit. Check the sheet that comes with your kit for diagrams.

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