How to: Clarks Toilets

January 9, 2023

Whether you’re new to Clarks Vehicle Conversions or a seasoned user of our product, you will certainly know the importance of keeping a van clean and tidy.

One area you will definitely want to prioritise is the hygiene and upkeep of your toilet, and any failure to do so will soon become apparent by the odious smell that will greet you on entering your van.

Toilets Installed in Clarks Welfare Vehicles are available in manual or electric models and are very simple to manage and maintain once you become familiar with their operation.

Below we take a look at how to successfully prepare, operate and empty the waste cassette.


Before use, it is essential that the toilet is prepared correctly (this is pretty much the same process for both manual and electric toilets). After closing the toilet valve blade, the cassette can then be removed via the cassette access door. Once the cassette has been removed, it is set in an upright position with the spout rotated upwards. The cap is then used as a measure for the required amount of toilet additive fluid. It’s worth bearing in mind that some sites will insist on environmentally friendly additive products so perhaps consider this before making a purchase. Once added, this is then topped up with 2-3 litres of clean water and the cap replaced before returning the cassette into position.


Thetford C220CW

Once the waste cassette is in place, locate the valve blade at the right-hand side of the toilet bowl which should be in the closed forward position. Pumping the flush handle adds water to the bowl and then, after use, the valve blade is slid backwards to open the valve blade and the pump handle pumped until the bowl is empty. Finally, close the valve blade ready for the next use. You will know when the cassette is full as the indicator will turn red. The water can be topped up via the freshwater hatch, but chemicals must not be added this way; always lock the clean water hatch to prevent leakage.


Thetford C403L

As you would expect with an electric toilet, most of the manual tasks are completed using push button controls. Firstly, check the freshwater level on the control panel (the toilet will not flush if the level is too low) , locate the infill cap and top up as necessary. As with the manual toilet, do not add any chemicals to the freshwater supply. Close the valve blade and press the blue flush button to add water to the bowl. After use, turn the handle to open the valve blade and then flush until the bowl is empty before again closing the valve blade. Once the waste cassette is full, a red indictor will show and the toilet will not flush.


For both manual and electric toilets, emptying the waste cassette follows the same process. Close the valve blade and remove the cassette. Transport your cassette to the correct disposal station and rotate the spout into the upwards position. Unscrew the cap and dispose of the waste whilst keeping the airlock button pressed. Return the cassette to your van and re-fit ready to be used again.

Some useful tips:

  • Use a waste cassette cleaner once in a while for extra freshness
  • In warmer weather, protect against bad smells by regular cassette emptying
  • To avoid unnecessary bad odours, always close the valve blade after use
  • Always use recommended brands of dissolvable toilet paper to avoid blockages
  • Wear protective gloves when disposing of waste or when handling chemicals

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