2009 Jayco Thetford Toilet Valve Replacement

A Thetford toilet valve replacement starts with identifying the toilet: an Aqua-Magic Style II commonly uses water valve part 42049, while an Aqua-Magic V commonly uses part 31705. The Jayco model year may not identify the toilet or its valve, so start with the toilet’s model and date-code sticker rather than ordering by RV year. This guide helps you diagnose the leak or flushing problem, match the correct valve, replace it safely, and test the repair.

Use this quick check before buying parts or taking anything apart.

Symptom	Likely Cause	First Check
Water leaks behind or beneath the toilet when the pump is on	Water valve, inlet fitting, or supply connection	Dry the area, pressurize the water system, and look for the exact wet point
Water keeps running into the bowl	Water valve is not closing fully	Shut off the water supply and inspect the valve area
Pedal moves but little or no rinse water enters the bowl	Water valve, clogged inlet screen, or disconnected water line	Confirm the fresh-water supply is on and inspect the valve and line
Toilet flushes but the bowl will not hold water	Waste-ball seal or lip seal, not the water valve	Inspect the bowl seal and waste-ball area
Pedal is loose, broken, or does not operate the flush mechanism	Pedal, cable, or flush mechanism	Inspect the pedal linkage before replacing the water valve

Identify Your Thetford Toilet Before Ordering

A Thetford RV toilet water valve is not the same as the fill valve inside a household toilet tank. It is the small valve or water module that admits fresh water to the RV toilet when you press the foot pedal.

Look for a model name, model number, and date code on the toilet base. Check around the rear of the base and near the pedal side. Clean dust or residue gently so the sticker can be read; take a clear photo before ordering a part.

A single foot pedal does not identify the toilet model. Both Aqua-Magic Style II and Aqua-Magic V toilets use one pedal, even though their service parts differ.

If the identification sticker is missing, compare these details:

Whether the toilet has a foot pedal, hand lever, or wall-mounted flush switch.
Whether it has one pedal or two.
The pedal’s position when seated: left side or center.
The toilet’s base shape, bowl shape, and color.
Any molded numbers on the back or underside of the base.

The mounting points, water connections, and pedal-actuator design can differ among Aqua-Magic models.

Match the Correct Water Valve to the Toilet

Water-valve part numbers vary among Aqua-Magic models, so confirm the toilet model and date code before ordering.

Toilet Model	Common Water Valve Part	What to Confirm Before Ordering
Aqua-Magic Style II	42049	Confirm the Style II model and date code; this is the Water Valve Kit for Aqua-Magic Residence and Style II toilets
Aqua-Magic Residence	42049 family	Confirm the Residence version and the kit listing for its date code
Aqua-Magic V	31705	Confirm it is an Aqua-Magic V pedal-flush toilet, not another Aqua-Magic version
Unknown, electric, cassette, or wall-panel-flush toilet	Do not guess	Identify the toilet model before ordering any valve

For an Aqua-Magic Style II or Residence, Thetford lists a dedicated Water Valve Kit service kit for Aqua-Magic Residence and Style II toilets.

Order the valve kit, not merely a loose generic valve. A proper kit should match the water-line ports, mounting arrangement, and pedal-actuator connection for your toilet.

How to Replace a Thetford RV Toilet Water Valve

Use this procedure only for a permanent, foot-pedal Thetford toilet with an accessible water valve or water module. Stop if your toilet has an electric flush system, a cassette toilet layout, damaged plumbing, or a valve that cannot be reached without removing the toilet from the floor.

Step 1: Shut Off and Depressurize the Water System

Turn off the RV’s water pump.
Disconnect city-water service if the RV is connected to it.
Press the toilet pedal briefly to release pressure from the toilet’s water line.
Open a nearby cold-water faucet momentarily to release remaining pressure in the RV plumbing.
Place paper towels or a shallow container below the valve area.

I prefer shutting off the water first because it makes toilet repairs cleaner and calmer.

Step 2: Expose the Water Valve and Photograph the Connections

Empty water from the bowl with the pedal, then dry the bowl and floor around the toilet.
Remove only the trim cover, access cover, or small shroud needed to reach the valve.
Locate the fresh-water inlet line and trace it to the valve or water module.
Take photos of the incoming line, outgoing rinse line, mounting screws or clips, and pedal linkage.

The water valve is on the fresh-water side of the toilet. Do not confuse it with the waste-ball mechanism below the bowl or the black-tank dump valve outside the RV.

If the valve is hidden behind the toilet and access would require loosening the toilet’s floor bolts, stop before removing the toilet. Disturbing the floor seal can create a sewer-gas or waste leak, which is better handled by an RV service professional.

Step 3: Disconnect the Water Lines

Keep towels under the valve.
Hold the valve body so it does not twist while you loosen the incoming water connection.
Disconnect the incoming fresh-water line.
Disconnect the line leading from the valve to the bowl rinse system, if your valve design has a separate outlet tube.
Let trapped water drain into the towels or container.

Some Thetford valves use threaded fittings, while others use retaining clips, clamps, or quick-connect fittings. Do not force a connector that does not release easily. A fitting that seals with a rubber washer does not need plumber’s tape; tape is only for a threaded connection designed to seal at the threads.

Step 4: Remove the Old Valve or Water Module

Remove the mounting screws, retaining clip, or bracket that holds the valve in place.
Disconnect the pedal linkage or actuator from the old valve if applicable.
Lift out the valve and compare it with the replacement before installing anything.
Check that the inlet and outlet ports, screw holes, and actuator position match.

If the new part has a supplied gasket, O-ring, or seal, use the new one. Do not reuse a flattened, cracked, or distorted seal from the old valve.

A mismatch at this stage means the replacement part is wrong for the toilet. Reinstall the old valve loosely enough to keep the plumbing protected, keep the water system off, and obtain the correctly matched kit.

Step 5: Install the New Valve

Position the new valve exactly as the old one was installed.
Attach the pedal linkage or actuator before tightening the mounting hardware, if that gives you better access.
Secure the valve with its original screws, bracket, or retaining clip.
Reconnect the outlet line and then the incoming water line.
Tighten fittings firmly by hand and with only the tool pressure needed to seat the connection without cracking plastic parts.
Move the pedal by hand to make sure it can operate without binding.

The valve must be installed in the same water-flow orientation and actuator position as the old part. Reversed ports or a misaligned pedal linkage can cause a leak, continuous water flow, or a pedal that does not flush.

Step 6: Reassemble and Test for Leaks

Reinstall the access cover or trim panel.
Turn on the RV water pump or reconnect city water.
Watch the valve, both water-line connections, and the floor around the toilet for leaks.
Press the pedal briefly to add rinse water, then release it and make sure the water stops.
Flush the toilet several times while watching the valve and fittings.
Dry the area again and recheck it after the system has remained pressurized.

For an Aqua-Magic V, Thetford specifies that pressing the pedal halfway adds water and pressing it fully activates the flush. Test both pedal positions after the repair; a valve that works at one position but not the other may have a pedal-linkage issue rather than a bad valve. The Aqua-Magic V’s owner information confirms this half-pedal and full-pedal operation.

A normal water-saving RV toilet flush uses about 1 quart of water.

When the Water Valve Is Not the Problem

Replacing the water valve will not fix every toilet symptom. Isolate the actual failed part before ordering more components.

Bowl Will Not Hold Water

If the toilet rinses and flushes normally but water drains from the bowl while the pedal is released, the likely problem is the waste-ball seal or lip seal. The water valve controls rinse water; it does not seal the bowl outlet.

Thetford recommends replacing a lip seal every four to six years, depending on how often the toilet is used. A worn seal can let bowl water drain slowly even when the valve and pedal work correctly.

Pedal Is Loose, Cracked, or Will Not Return

A damaged pedal, cable, spring, or flush mechanism can prevent the valve from opening correctly.

For an Aqua-Magic V, test the pedal halfway for water addition and fully pressed for flushing. If the pedal does not reach either position properly, the mechanical pedal system may need repair.

Leak Comes From the Base or Floor

Water or odor at the toilet base can indicate a damaged floor seal, loose mounting hardware, cracked toilet base, or waste-system problem. Turn off the water if fresh water is leaking, avoid using the toilet, and arrange RV service if the problem involves waste, sewer odor, or a floor-level seal.

The Problem Is the Black-Tank Gate Valve

The black-tank gate valve is part of the RV’s dump plumbing, usually near the tank outlet or termination connection. It is separate from the toilet water valve and waste-ball seal. A toilet water valve kit will not repair a leaking or stuck tank gate valve.

Confirm the Repair and Prevent Another Leak

Before putting the toilet back into regular use, run through this short check:

The water pump stays off when no fixture is being used.
No water appears at the valve, supply fitting, or toilet base.
The pedal returns freely after being released.
Water enters the bowl only when the pedal is pressed.
Water stops immediately after the pedal is released.
The toilet flushes completely without sticking or binding.
The bowl holds water if the waste-ball seal is in good condition.

Keep the model number, date code, and valve part number with your RV maintenance records. That makes future repairs easier, especially if you later need a pedal kit, nozzle assembly, vacuum breaker, waste-ball seal, or seat-and-cover kit.

Frequently Asked Questions

How Do I Know Which Replacement Toilet Fill Valve to Buy?

Buy a Thetford water valve that matches the toilet model and date code, not a household toilet fill valve. Aqua-Magic Style II toilets commonly use part 42049, while Aqua-Magic V toilets commonly use part 31705. Confirm the part against the model sticker and the matching Thetford service-kit listing before ordering.

Does One Foot Pedal Mean I Have an Aqua-Magic V?

No. Both Aqua-Magic V and Aqua-Magic Style II toilets use a single foot pedal. Identify the toilet from its model and date-code sticker, base shape, and matching service parts instead of using pedal count alone.

Can I Replace the Thetford Toilet Valve Without Removing the Toilet?

Usually, yes, if the water valve is reachable behind a trim panel or near the pedal mechanism. Disconnect the RV water supply, remove the access cover, replace the valve, reconnect the lines, restore water pressure, and test for leaks. Do not remove floor bolts unless you are prepared to replace the toilet’s floor seal and address any waste-system issues.

How Do I Change the Flush Lever on a Thetford RV Toilet?

Many Thetford RV toilets use a foot pedal rather than a flush lever. If the pedal is cracked, loose, or fails to move the valve linkage, replace the pedal or mechanism kit made for that toilet model; a new water valve will not repair a broken pedal. Keep the water supply off while working around the pedal linkage, then restore pressure and test for smooth operation and leaks.

What Are the Common Replacement Parts for a Thetford RV Toilet?

Common service parts include the water valve, pedal or pedal cable, nozzle assembly, vacuum breaker, bowl or waste-ball seal, waste ball and drive arm, seat and cover, and base hardware. Match every part to the exact toilet model because similar-looking Aqua-Magic parts are not always interchangeable. If the new valve leaks or the toilet has a base-level waste leak after reassembly, shut off the water and have an RV service professional inspect it.