The C400 waste cassette can be serviced independently of the installed toilet body. Thetford's detailed exploded tank drawing shows the sliding cover, blade and seals, pour-out elbow, vent mechanism, pull handle and wheels. Use it to distinguish parts of the cassette from the C402C or C403L flush-water equipment.

Matching C400 cassette repair parts and complete tanks

The lip seal, pour-out spout and blade-opening mechanism are separate service parts. The complete 19 L waste tanks are sold in left-hand and right-hand versions. Compare the original part number and tank orientation before choosing a replacement.

Thetford 23721 black rubber C400 waste-cassette lip seal for the blade opening
Thetford 23721 C400 Waste-Tank Lip SealDrawing callout 8. Seals the sliding blade opening; different from the pour-out spout and its cap.
Thetford 3232606 C400 Left-Hand Cassette Waste Holding Tank, 19 L — NewRVParts catalog photograph
Thetford 3232606 C400 Left-Hand Cassette Waste Holding Tank, 19 LComplete 19 L left-hand waste cassette, part 3232606. Confirm the access-door side and tank orientation.
Thetford 3232706 C400 Right-Hand Cassette Waste Holding Tank, 19 L — NewRVParts catalog photograph
Thetford 3232706 C400 Right-Hand Cassette Waste Holding Tank, 19 LComplete 19 L right-hand waste cassette, part 3232706. Not the left-hand version.
Thetford 3230606 C400 Cassette Waste Tank Pour-Out Spout with Cap — NewRVParts catalog photograph
Thetford 3230606 C400 Cassette Waste Tank Pour-Out Spout with CapPour-out spout with closing cap, part 3230606 (drawing callout 30). Used when emptying the cassette.
Thetford 3233206 C400 Left-Hand Cassette Tank Mechanism - Gray — NewRVParts catalog photograph
Thetford 3233206 C400 Left-Hand Cassette Tank Mechanism - GrayGray left-hand blade-opening mechanism with handle, part 3233206. The sliding cover is supplied separately.

Original manufacturer exploded-view drawings

Find the numbered reference on the factory drawing, then use the table below to identify the original manufacturer part number. Open the full PDF to enlarge small components.

Manufacturer exploded illustration

Open the original manufacturer's document for a zoomable parts drawing.

Open manufacturer exploded illustration (PDF)

Numbered parts table

Open the original manufacturer's document for a zoomable parts drawing.

Open numbered parts table (PDF)

Additional numbered parts

Open the original manufacturer's document for a zoomable parts drawing.

Open additional numbered parts (PDF)

Component numbers and descriptions

These are original parts references for the model or tank shown. Entries without a product link are included for identification; where NewRVParts has an exact-number match, you can review its listing.

Callout Original no. Component Product
1 32301 Sliding waste-cassette cover
2 — Blade opener
3 32300 Washer (included in matching mechanism service assembly)
4 32300 Mechanism seal
5 32300 Mechanism retainer
6 32302 Left-hand tank plate
6 32328 Right-hand tank plate
7 50724 Mechanism seal
8 23721 Waste-opening lip seal View matching part
9 — Seal plate
10 32331 Right-hand operating mechanism, historical number
10 32332 Left-hand operating mechanism, historical number
11 — Mechanism retainer
12 32304 Float mechanism magnet
13 32304 Float arm assembly
14 50731 Waste slide blade
15 — Blade bearing
16 — Blade operating arm
17 — Bushing
18 — Screw
19 — Blade driver
20 — Support track
21 — Support screw
22 — Vent lid
23 — Vent lifter
24 — Vent spring
25 32305 Vent-pivot and float service assembly
26 32305 Vent seal included in assembly
27 32305 Float stem included in assembly
28 32305 Float included in assembly
29 — Vent actuator
30 32306 Pour-out spout, older original reference
31 25810 Measuring cup; older original number
32 — Spout O-ring
33 — Transport-handle cover
34 — Handle screw
35 — Pull handle
36 — Vent clip
37 — Vent button
38 32307 Vent spring and seal assembly
39 32307 Vent seal included in assembly
40 — Waste tank upper body
41 — O-ring
42 — Wheel support bracket
43 51805 Pull-handle service assembly
44 51805 Handle bushing, supplied as assembly
45 51805 Pull-handle spring, supplied as assembly
46 51801 Tank lock clip
47 — Transport wheel
48 32308 Wheel bearing, right
49 32308 Wheel bearing, left
50 — Waste tank lower body
Complete L 3232606 Newer complete left-hand waste tank View matching part
Complete R 3232706 Newer complete right-hand waste tank View matching part

Check the right model and part

There are left- and right-hand C400 cassette versions. Thetford's earlier waste-tank drawing lists 32326 and 32327; its November 2025 C402C/C403L list gives the updated complete tank numbers 3232606 (left) and 3232706 (right). The two are not interchangeable by orientation alone.

Before replacing a tank, valve or seal, confirm the original toilet model, manufacturer number and production version. Follow the manufacturer instructions and isolate the water and electrical supply when servicing fixed toilets.

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