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Caravan Toilet Chemicals: Everything you need to know but don't want to think about


Caravan puts a peg on its nose and explores the green, blue and pink world of loo chemicals only to find the whole toilet business is a triumph of nature.

Written by Mark Williams

You often hear that caravanning is one of the most environmentally-friendly holidays you can take. OK, you may burn a little more fuel getting to the site, but after that, we caravanners are as 'green' as an episode of The Good Life.

That is particularly the case of our, ahem, toilet habits. At home, we just hit the flush, then gallons of treated drinking water take away the waste. We never spare a second thought for what happens next.

Caravanners, on the other hand, are more connected to the business of, erm, our business.

The amazing thing is that nature is put to work cleaning up our toilet waste – whether underground in a septic tank or at the sewage works. Bacteria and enzymes gleefully munch through the nasty stuff on our behalf. Bless them all.

sewage treatment plant

A toilet cassette will go a day or two without emptying; a single flush of the loo at home would fill one. Loads of water saved, right there. The downside is that we 'home' the poo for a while, and while we're looking after it, we don't want to know about it.

Enter stage left the toilet chemical; the caravanner's friend. But what is it? How does it work? Is it poisonous? Do some work better than others? Why are some pink and some green or blue? Come to that, how does the loo itself work? And why did I get to write this feature?

Caravan toilets

caravan toiletWhether you have a 'teardrop' caravan or a twin-axle six-berth, a loo is essential. Most people make use of the site toilets whenever they can, but in the dead of a rainy night with the toilet block 200 yards away?

For some teardrop owners, the solution is a portable loo, perhaps sitting outside in its little tent or the awning. These toilets, such as Thetford's Porta Potti, are excellent, with a nice manual flush and detachable tank for emptying, working on the same principle as any caravan chemical toilet.

Thetford and Dometic both make fitted, flush loos, which empty the waste into a cassette which can be carried or wheeled to a disposal point. Both brands are excellent, and work along the same principle, with an air-tight 'shutter' valve which opens when you use the loo and close afterwards.

Freshwater-flush loos aside, most have a flush tank (that usually uses the ‘fragrant’ pink fluid, diluted). You also add a diluted liquid (usually blue or green) or tablets to the waste storage tank before use.

There's a procedure for using any cassette loo – lift the lid, open the valve, give the flush a quick go (to prevent, er, adhesion), do your business, flush again, close the valve and drop the lid.

Finally, the shutter valve on the cassette will work much better if you periodically spray it with a silicone lubricant, when the cassette is washed and dried. Thetford makes one, especially for the purpose. Don't use conventional automotive lubricants, which can damage the plastics and rubber seals.


Loo paper

loo paper

Luxury domestic loo paper, such as Thetford's Aqua Soft loo roll, is simply too bulky, clogging and absorbent to work well in caravan loos and septic tanks. It's a small sacrifice to buy quick-dissolve paper or even to nip to the pound shop and get their cheap paper, which tends to work as well. You'll thank us one day, when you see someone trying to empty a cassette, leaning over the disposal point while grimly jabbing the seeping lump of blockage with a stick.

Grey water/foul sewer

grey water chemicalsGrey water is the stuff from the shower and the sink, usually contaminated with nothing nastier than some dishwater and detergent. It's biodegradable (please use 'bio' washing-up liquid, not 'anti-bacterial') and can go straight into the soil via a seep tank for the soil microbes to digest. It shouldn't go into surface drainage, which is for rainwater.

Chemical toilet waste is 'black water,' and needs to go into the site's chemical disposal point or, if that's not available, be flushed down a loo. Never confuse the two. Pay attention to your site's maps, rules and notices.

Greywater chemicals, such as Elsan's Grey Water Tank Fresh, keep your storage tank smelling fresh and minimise harmful bacteria growth.



Caravan toilet chemicals Blue Bio Chemical toilet fluid

There are two core functions of toilet chemicals that go into the cassette: to reduce odours and to help break down the waste. In fact, many older formulations only damp down or disguise the smell, rather than eliminating it.

Many chemicals contain formaldehyde, a toxic compound which is banned on many environmentally-friendly campsites as it can damage the ecosystems they use to dispose of waste.

These days, there is a good choice of formaldehyde-free chemicals, that are altogether less damaging. The bottle should describe the contents; if not, ask the supplier or find this information on the company's website.

These increasingly use enzymes and natural substances, which aid the decomposition of the waste.

Our research indicates that the following do NOT contain formaldehyde:

Others may be available.

Snagging a bargain

caravan accessory shopFor the same reason, that motorway services are bad places to fill up your car; the caravan site may not offer the best toilet chemical deal.

That's not a criticism of caravan sites, who stock the stuff to help bail you out of weekend misery without traipsing around the shops.

Indeed, if you are 'caught short' without toilet chem, weigh up the cost of a special trip to get a 'bargain' against just buying a small bottle at the caravan site. You'll usually get a better deal at caravan shops, on-line or even at the German supermarkets when they run their 'caravan special deals.'

We've seen chemicals, which typically cost £8, going for £18 in a campsite shop. Now that's what we call a ‘distress purchase'!

Some companies have their own-brand chemicals, which should be very cost-effective, but check what’s in them if you care about the planet!






My toilet has started to smell. What can I do?

silicone lubricantFirstly, check that you've added fluid to the tank, test the shutter valve is closed, and remove the cassette to see if it's leaking. If the unit is leaking, it can be fixed quite cheaply, but wash it very thoroughly, inside and out, then lubricate the shutter valve and see if that cures the problem. Also, try using different toilet fluids, until you find one that suits you.

I can't get the shutter valve to close. Can it be fixed?

Yes, but you'll need a new sealing kit from the manufacturer or a caravan shop and some basic tools. It's far better if you wash and check the cassette before your trip. Also, spray the valve with a little silicone lubricant, like 3-in-one Professional.

My manual flush pump has stopped working. Can it be fixed?

Again, yes. It's either a failed valve or failed bellows, and it's not too difficult to fix if you have the replacement parts and the instructions. However, if you're already on site, just fill up a bottle with diluted flush fluid and use that for the time being.

My cassette doesn't seem to want to empty out. How do I fix it?

First of all, ensure you are using the air release button at the top of the cassette, because you may just have an air lock. Then, replace the drainage cap, and give the cassette a vigorous shake, which may break up the blockage. If that doesn't work, use the hose at the disposal point straight into the drainage pipe – just a short, powerful squirt – then try shaking it again. Keeping your mouth closed and holding your breath at all times!

I can't stand emptying the cassette. Could it be more sanitary?

Firstly, our waste is nowhere near as nasty as you'd think; it was all inside your body a few hours ago! But, gloves if you're anxious about it, you should wear disposable, and always wash your hands immediately after emptying.

If you get splashed, wash the splashes, too. The risk is an upset tummy from eating your gut bacteria or if you use a formaldehyde-based toilet chem, skin irritation.

I have a 1990s caravan with a Thetford C3 toilet, and the cassette is heavy when full. Can I fit a newer toilet?

No need. Thetford now makes a direct replacement cassette for C2, C3 and C4 loos, which has wheels and a folding handle, so for £80 or so, you can easily upgrade. It even has a useful chemical measuring cap. The Caravan Specialists carry a range of Thetford spares and replacements.

What's the fuss about formaldehyde?

Blue BioFormaldehyde is a toxic substance, which minimises smells because it is a biocide. Formaldehyde kills the bugs in poo, which are the cause of the bad odours. Unfortunately, it's those same bugs, which, at the sewage works or septic tank, help process your waste into harmless effluent.

Although formaldehyde does break down eventually, there are concerns that it can cause real problems until this happens, and many loo chemicals are now declared 'formaldehyde free.'

Mike Borowski, Managing Director of Blue Bio, says some formaldehyde-free loo treatments just substitute other chemicals which could potentially do the same thing: “But we were among the first companies to produce biological loo treatments,” he says.

“Blue Bio has food-grade acids and colourant, plus bacteria which produce enzymes to break down the waste and reduce the smell. They carry on working in the sewage system.”

Back to "Practical Advice" Category

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