Thetford Cassette Holding Tank

This story happened on: 01/10/2021

Hi can anyone let me know I’ve just recently bought a motorhome and as such decided to give it a thorough clean when opening the cassette holding tank there were brown sort of scratch marks on the white plastic in addition to this inside the cassette holding tank there is a white cylinder type plastic floating about in it does that mean maybe the brown marks the cassette is leaking and is the cassette broken 😀😀

Google map showing location of Tyrone, Omagh, UK

dwandjamartin commented on 13/12/2021 12:32

Commented on 13/12/2021 12:32

Hi markymark,

That sounds like your holding tank has leaked in the past and the water has been allowed to dry without being cleaned, thus leaving horrible brown stains on the white plastic. 

The white plastic thingy floating about inside the tank is probably the air vent sealer that springs shut when you pull the cassette out to empty it. It shouldn’t be floating about. They are replaceable and are quite easy to fit. Or you could buy a whole new fresh up kit.

I have had the same problem in the past. I now take the cassette home every winter and give it a good clean and replace all the air vent pieces and the rubber seal on the sliding access hole.

hope that helps.