The murky world of caravan toilet fluids
Chris Hogan, 18th January 2016, Caravan
On the grounds that not many of you will be taking your caravan out at this time of year we thought it was a good time to investigate the world of caravan toilets. Which fluid type is best? And we have news of a neat little gadget that might make the whole toilet business a lot easier.
Image courtesy Thetford Europe
Elsan is synonymous with chemical toilets in the same way that Hoover is with vacuum cleaners and that's because the first viable chemical toilet system was invented in London by E.L.Jackson - hence EL and 'SAN' for sanitation.
Formaldehyde
That was nearly a hundred years ago and there are many more manufacturers and chemicals available today. But that in itself presents a problem - which is the best type of chemical to use? And, as is often the case, the answer isn't straightforward.
Early toilets used formaldehyde which is a pretty smelly and aggressive chemical and although you can still get formaldehyde based fluids, most manufacturers are have developed more benign mixes which will still break down waste and combat aromas. Broadly speaking there are two groups of chemicals known as 'blue' or 'green', although the actual colour of the fluids sometimes doesn't always match the name.
Blue fluids
These are biocides which break down or kill bacteria in the same way that a septic tank works and were originally dyed blue simply because that seemed to be the best colour for obscuring the contents in waste tanks.
The benefits of blue fluids are that they have a wider working temperature and will even work properly after being frozen, so they suit those who tour all year round. They also start working intermediately.
Green fluids
These are more biological than chemical and the 'green' refers to the fact that they are designed to be less harmful to the environment. Because they are biological they take longer to start working and in cold temperatures (less than 5C) they may not work at all.
Site rules
Note that some sites will, as you'd expect these days, insist on only green chemicals being emptied into their systems because of their less aggressive nature, and will specifically ban any formaldehyde. This is particularly true of sites with reed bed sewage systems, although those aren't common.
However, perhaps a little more surprisingly, some sites ban green fluids. This will be on the grounds that they are slower to break down waste so don't work so well in the site's sewage system.
Other options
Many manufacturers provide their fluids in concentrated sachet form - you drop them into the tank but most make sure they have dissolved before using the toilet. They are usually more expensive than the equivalent fluid but are lighter and easier to carry.
There are also concentrated fluid versions of some products available too, just make sure you dilute them according to the manufacturers instructions. Might be useful on a long holiday as they'll take up less space.
The Thetford Machine
At the beginning of this article we promised new of a gadget intended to make the whole messy business a lot easier - the Thetford machine. The Camping and Caravanning Club has been helping Theford to promote this and installed a machine at its site near the NEC Motorhome and Caravan Show back in October.
All you need to do is place your Thetford cassette in the machine and follow the pictorial instructions. In three minutes the machine will empty the cassette, flush and clean it and refill in with fresh chemicals, ready to be used again.
On trial
Although it's not yet generally available on UK sites Thetford already have it on trail at ten Dutch sites where the service costs €3.50, using contactless payment or a pre-paid swipe card.
Obviously it will only be of use to caravan owners with Thetford systems, and at the moment the machine will only refill cassettes with Thetford Aqua Kem Blue, so you're out of luck if you prefer green, at least for the moment.
But it's early days for this intriguing idea and if it catches on it will be interesting to see whether other manufacturers follow suit.
