thetford cassette toilets

[kelly58]

We have a new motorhome with a thetford cassette toilet installed, the manual advises not to travel with the flush tank loaded,  is this the norm or is it ok to travel with the flush tank with liquid in it because its obvious when you need to use the toilet en route its not going to be very convenient to to have to fill the flush tank every time.Up until now we have not used the on board loo because there has been all the facilities we need on site, but as we will be travelling further afield the need to use our own loo will become evident especially if the site amenities are minimal. 

regards kelly

[Miami]

We have had a few caravans with flush tanks and have never emptied them when travelling. I think Thetford are only covering themselves in case there is a leak. This is most unlikely in an MH. Caravans sway about all over the place and we have had the odd slight leak.

We now have a toilet that feeds from the main tank in the MH so no flush tank. Might be worth converting it!

[Guest starspirit]

It is often easier to empty the tank when I get home and sometimes we travel a long way with a full or nearly full waste tank with no harm or leaks.

 

Have done for many years and never a problem

 

Driving does tend to break down the larger elements which makes the outpouring easier, but do remember to release the internal pressure by pressing the button prior to opening or you might just get a nasty surprise.

[Derek Uzzell]

Kelly:

 

Congratulations on taking the trouble to read your new motorhome's instruction manuals!

 

Although Thetford's recommendation to travel with the flush-tank empty is headed "Important Warning Notice!", it's most unlikely that ignoring that advice will present problems with a motorhome that, as Miami says, will be a whole lot more stable than a caravan. I always used to travel with water in the flush tank and never experienced problems and I've never heard of anyone who has.

 

 

[Guest peter]

I didn't know Motorhomes had flush tanks. Our Rapido has electric flush and takes it's water from the main tank.

[carioca]

starspirit the question was about the flush & not the waste tank (!)

[Guest Frank Wilkinson]

I always travel with water in the flush tank, both in my tourer when we had one and in my new motor home. The whole pleasure of having your own loo, is being able to use it en route.

I suspect that Thetford worries about the touring caravan aspect where full tanks may exacerbate any swaying that starts.

When the company manufactures its lavatories it has no idea whether they're going into a motorhome or a touring 'van and must always assume the worst case scenario.

[Derek Uzzell]

Frank: The 'Important Warning Notice' in Thetford's instruction leaflet states:

 

"Please do not travel with water in the flush tank of your toilet. Failure to adhere to this notice may result in water damage to your caravan or motorhome."

 

So it's water leakage that Thetford is specifically concerned about, though (as you suggest) the on-road behaviour of any caravan can only benefit from dispensing with unnecessary weight before travelling.

 

Peter: When Thetford bench-type toilets are fitted to motorhomes I'd take an educated guess that water for flushing will usually come from the toilet's integrated reservoir (though there are bench models - C3 and C-403L - that use water from the vehicle's main freshwater tank). The design of the bench toilet lends itself to having a substantial capacity built-in flush tank with access for topping-up via the cassette locker. Basically, with a 'bench' there's not a great deal to be gained by opting for the main-tank-fed versions.

 

I'd guess that most swivel-bowl toilets flush via the motorhome's main freshwater tank, although UK motorhome builders seem to have a fondness for C200 toilets with their own reservoirs. The advantages of the latter for the constructor are that it simplifies the motorhome's plumbing and electrical wiring (particularly when a manual-flush model of toilet is chosen) and avoids any impact on a small capacity freshwater tank (another UK motorhome design tendency). It also permits the motorhome owner to continue to utilise the toilet when the 'van's main water system has been drained down (and, of course, to put that strange Pink Stuff in the flush tank!) The downside for the owner is not so much the hassle of filling up 2 separate water reservoirs, but that the need to top up the flush tank will be pretty frequent if the toilet is regularly used. Flush tanks on swivel-bowl toilets are only 8.3 litres capacity (electric flush) or 7 litres (manual flush), as opposed to the 15 litres of the bench models.

 

One might expect (as you did) that all Thetford swivel-bowl toilets in motorhomes would flush from the main freshwater tank, as it's the logical solution and the design of the toilet itself can be made much more compact. But, hey, since when have motorhome builders been logical?