Q What’s causing our Thetford toilet to leak in our motorhome?

We have a Thetford C260 toilet in our motorhome, which we bought last October. For obvious reasons, we’ve hardly used the ’van, but we’ve always been aware of an unpleasant smell in the washroom.

Whist on a trip last week, the smell got far worse, which we put down to the warmer weather. However, a thorough investigation when we got home revealed that all the cavities under the cassette were full of urine, including under a removable plastic lid.

We rang Thetford, which was not at all helpful and suggested that there was a leak in the holding tank. If this was the case, the urine would be diluted with water and chemical, but this was pure urine.

We are at a loss to know how this can happen. Any thoughts, please?

Christine Turrell

A

This is not a normal situation – one of the great things about these loos is that they don’t tend to leak and encapsulate liquids brilliantly.

So, something has failed or perished. There is only one seal and it’s on the loo cassette. It’s best to only use the loo with the blade fully open – it reduces the chance of leaks.

Replacing the cassette seal is a relatively easy job. To access the screws holding the seal in place, which are inside the unit, use the cassette slider cover as a lever by sliding it half out and rotating the whole mechanism anticlockwise (there is a marker arrow and a couple of dots moulded into the cassette so you know where to move it to).

Inside, unscrew the blade screw, slide the blade out of the way and then remove any screws around the circumference of the seal (note its orientation).

Clean everything up and refit the new seal with the bevelled edge facing downwards. A smear of olive oil will ease installation.

You can buy the seal separately for the holding tank for under £15, or an entire new top section for easier replacement for about £45.

If urine has leakedout underneath the base of the toilet, this will definitely need a thorough clean – including the vent compartment in the base (this just clicks out of place).

Peter Rosenthal