How to Clean and Maintain a Caravan Cassette Toilet
A cassette toilet is a marvellous invention. It allows you to enjoy all the comforts of home while parked miles from civilisation – right up until the moment it reminds you, quite forcefully, that somebody still has to empty it.
Once released, the cassette can be pulled from the service compartment for emptying and cleaning.
Key points
- Empty the cassette when the ¾-full warning appears rather than waiting for the FULL light.
- Use cleaning products designed specifically for cassette toilets and avoid harsh household chemicals.
- Clean and lubricate the blade seal regularly to keep it operating smoothly and help prevent odours.
- Treat the internal level-indicator float carefully – it is a small but important component that can be easily damaged.
- Give the cassette a thorough clean periodically, including the vent, emptying spout, cap and cassette compartment.
- Before long-term storage, empty, clean and dry the cassette and inspect the seals and moving components.
Fortunately, there isn’t much inside a cassette toilet that requires regular attention. A little routine cleaning, looking after the seals and giving the cassette a proper clean occasionally will prevent most problems before they start.
And this is definitely one of those maintenance jobs where prevention is preferable to cure. Discovering that your wheel bearings need attention is inconvenient. Discovering that your cassette toilet needed attention three days ago can change the entire atmosphere of a caravan.
Quite literally.
A typical caravan cassette toilet fitted neatly into a compact ensuite.
Empty it before it becomes a problem
Before doing any cleaning or maintenance, empty the cassette at an approved dump point.
Close the toilet blade inside the caravan before removing the cassette, then pull the cassette from its compartment. At the dump point, rotate the emptying spout through 90 degrees and remove the cap.
Now comes an important piece of advice learned from experience.
Before you lift the dump-point lid, put the cassette cap somewhere safe. Not balanced on the edge of the hole. Not sitting on top of the pole where your elbow can knock it off. And certainly not somewhere from which gravity can deliver it directly into several thousand litres of something you have absolutely no intention of reaching into.
Put it somewhere safe.
Once the dump-point lid is raised, tip the cassette so the contents flow through the spout and into the dump point. Press the air-release button while pouring. This allows air into the cassette as liquid leaves it, producing a reasonably smooth flow rather than the unpleasant glug-glug-surge arrangement that can rapidly turn an otherwise respectable pair of shoes into a biohazard.
Once empty, add a small amount of clean water through the emptying spout and gently move the cassette around to rinse the inside before emptying it again.
There is no need to continue rinsing until the water emerging from it resembles something bottled in the Tasmanian wilderness. A couple of sensible rinses is generally enough.
A moment of inattention at the dump point can turn a small cassette cap into a surprisingly important piece of equipment.
Don’t wait for the FULL light
Most caravan cassette toilets have some form of level warning, commonly a ¾-full indication followed eventually by a FULL warning.
Our rule is simple: as soon as the ¾-full light comes on, the cassette gets emptied.
You might reasonably assume that a 20-litre holding tank showing ¾ full has around five litres of capacity remaining. Mathematically, this is perfectly sound.
Unfortunately, mathematics has failed to take caravan occupants into account.
When several people are using the toilet, nobody really knows exactly when the ¾-full light first appeared. Everyone assumes somebody else noticed it. And at 1:30 in the morning, when the amenities block is half a mile away and the temperature outside has dropped to something normally associated with commercial refrigeration, nobody is volunteering for the walk.
So the toilet gets used again.
And probably again.
By 7am the FULL light is glowing enthusiastically and the person who finally gets nominated to empty the cassette opens the outside access door to discover that optimism has lost its battle with fluid dynamics.
This is why we empty ours at ¾ full. And if you choose not to heed this advice, don’t worry. You will remember it vividly the first time your cassette overflows.
The warning light on the toilet tells you when the cassette is approaching its maximum level.
Give the cassette a proper clean occasionally
Routine rinsing removes most loose material, but over time residue can build up inside the holding tank.
About every six months we give ours a thorough clean. Where the cassette design allows access, we open it up so we can properly clean the internal surfaces rather than simply pouring cleaner through the spout and hoping for the best.
We mainly use Thetford Duo Tank Cleaner and generally allow it to soak overnight.
Rotate the complete slide mechanism to approximately this position before lifting it off the cassette. The same angle helps when refitting it.
The cleaning instructions recommend making sure the solution reaches the internal surfaces, including agitating the cassette. We take a slightly different approach.
For the princely sum of about $1.50, we bought a Monarch 1–4L timber paint stirrer.
It may not be listed among the essential accessories in any glossy caravan brochure, and nobody at a caravan show is likely to unveil one beneath a silk sheet while dramatic music plays, but it does an excellent job of gently moving the cleaning solution around inside our cassette.
Most importantly, it allows us to control what is happening around the delicate components inside.
After soaking, empty the cleaning solution into an appropriate dump point and rinse the cassette thoroughly with clean water.
Whatever cleaning product you choose, use one designed for cassette toilets and follow the manufacturer’s dilution and soaking instructions.
New float on the left with both locating tabs intact, compared with the old float on the right with a broken mounting tab.
Why we don’t shake ours like a cocktail
This is worth explaining because there is a surprisingly delicate component living inside many cassette tanks.
The level indicator relies on a small internal float. As the liquid level rises, the float rises with it and, on many systems, a magnet associated with the float triggers the level indicator in the toilet above.
It is a wonderfully simple little device.
Be particularly careful with the float and its mounting. If the float is damaged, jammed or broken away from its retaining clips, the level indicator may no longer operate. That means no ¾-full warning and potentially no FULL warning either. At that point you are essentially operating the cassette on guesswork – and a toilet cassette is one piece of equipment where guessing the remaining capacity is not a game we recommend.
This is why we are not particularly keen on having the float belting around inside the cassette while somebody shakes the tank as though they are auditioning for the Saturday-night cocktail shift at Sandstone Point Hotel.
On our cassette, the float and its mounting are delicate enough that we would rather agitate the cleaning solution manually with the stirring stick than subject the whole assembly to enthusiastic shaking.
The exact design varies between toilet models, so check the instructions for your particular unit. The important point is to understand that there are actual working components inside the tank. It isn’t simply an empty plastic box with a handle.
The float mounting points inside the cassette are small, so care is needed when cleaning around them.
Be careful what chemicals you use
A caravan cassette is not the place to conduct chemistry experiments with whatever happens to be under the kitchen sink.
Strong bleach, abrasive cleaners, petroleum-based products and some household cleaning chemicals can damage rubber seals and plastic components.
The safest approach is to use products designed specifically for cassette toilets or products approved by the toilet manufacturer.
More chemical is not necessarily better either. If the bottle says use a particular amount, use that amount. Doubling the dose generally doesn’t produce twice the cleanliness. It simply means you have used twice as much chemical.
We use a measured dose of toilet chemical after the cassette has been cleaned and rinsed, following the manufacturer’s instructions.
Clean the toilet bowl separately
The toilet bowl needs regular cleaning just like the toilet at home, although the materials involved are generally quite different.
Many household toilet cleaners are designed for ceramic bowls. Caravan toilets commonly use plastics, rubber seals and other components that may not appreciate being attacked with the same chemicals designed to remove thirty years of scale from a porcelain public dunny.
Use a soft cloth or non-abrasive sponge with an appropriate cleaner. We normally use Thetford toilet bowl cleaner, which is readily available from camping and caravan stores.
Pay particular attention to the area around the blade opening. Deposits here can interfere with the seal and eventually make the blade harder to operate.
Look after the blade seal
With the blade open, inspect the rubber seal and surrounding area for dirt, damage or contamination before lubricating it.
One of the most important components in the system is the large rubber seal around the opening at the top of the cassette.
When the toilet is used, the sliding blade moves across this seal. If the seal becomes dirty, dry or damaged, the blade can become difficult to operate and odours may begin finding their way into the caravan.
This is generally considered undesirable.
Clean the seal carefully with water and a soft cloth. Once it is clean and dry, apply a lubricant suitable for rubber seals and recommended for the particular toilet.
We use SCA Silicone Paste, which is readily available from Supercheap Auto.
Avoid petroleum-based lubricants, oils and general-purpose grease unless specifically approved for the seal. Some can damage rubber compounds, while others leave a sticky film that attracts dirt and turns a simple seal into something resembling a fly trap.
The blade should operate smoothly without requiring excessive force. If it doesn’t, find out why.
Apply a light coating of suitable silicone grease to the cassette seal to help keep it lubricated and operating smoothly.
Check the cassette float
While the cassette is being given its deeper clean, have a look at the level-indicator float if it is accessible on your particular model.
The float needs to move freely. Residue or scale can restrict its movement, causing the level indication to remain on or, rather more worryingly, fail to illuminate when the tank is becoming full.
Be careful when touching it.
On some cassettes the float is retained by comparatively delicate plastic components, so don’t force it or start prodding it with tools simply because it looks as though it ought to move further.
It only needs to do its job.
If the level indicator isn’t behaving normally, consult the manufacturer’s instructions before dismantling anything.
Looking inside the cassette reveals the internal components, including the level-indicator float.
Check the vent
The cassette also needs to breathe.
Depending on its design, it may have a pressure-relief valve, automatic vent or connection to an external ventilation system.
If the vent becomes restricted, pressure can build inside the cassette, particularly in warm weather.
And there are few things in caravanning where the words pressure, build-up and toilet cassette appearing in the same sentence suggest that your day is about to improve.
During cleaning, inspect the accessible vent components and make sure they are clean and operating freely.
Don’t start poking screwdrivers into valves or pulling things apart unless you understand how that particular cassette is assembled. A blocked valve is annoying. A valve that used to be attached to the cassette is generally worse.
Check and clean the cassette vent while the tank is out, making sure it is clear and operating freely before the cassette goes back into service.
Inspect the emptying spout and cap
The swivel emptying spout gets plenty of use but very little attention.
Rotate it through its normal movement and make sure it moves smoothly. Inspect the cap and its seal and clean the mating surfaces.
A damaged cap seal can allow liquid to escape while you are carrying the cassette to the dump point.
If you’ve ever wondered why cassette tanks have handles, this is precisely the moment you’ll discover that carrying one at arm’s length while trying to keep it away from your trousers is not what the designer had in mind.
Replacement seals are inexpensive.
Replace a damaged one.
Don’t forget the cassette compartment
With the cassette removed, take the opportunity to clean the compartment beneath the toilet.
Dust, grit and the occasional spill can accumulate around the runners and locking mechanism. Wipe everything clean and check that there is nothing preventing the cassette from sliding fully back into position.
A damp cloth is generally all that’s required.
Resist the urge to attack the entire compartment with a garden hose. Depending on the installation, electrical connections, switches and level-indicator components can also live in there, and introducing litres of water to electricity rarely improves either system.
With the toilet cassette removed, take the opportunity to wipe out the cassette housing, runners and surrounding area before refitting it.
Preparing the toilet for storage
If the caravan is going to sit unused for an extended period, empty and thoroughly rinse the cassette rather than leaving waste or concentrated chemicals inside it.
Give it a final clean and allow it to dry.
Clean and lubricate the seals and follow the toilet manufacturer’s recommendation regarding the position of the blade during long-term storage.
If the toilet has a separate flush-water tank, check whether that should also be drained, particularly if the caravan may be exposed to freezing conditions.
Then, when the caravan comes out of storage again, give everything a quick inspection before use.
It is much easier to discover a dry seal or sticking mechanism while you’re standing beside the van at home than at 11 o’clock at night in a caravan park when somebody has just announced, rather urgently, that they need the toilet.
Before storing the caravan, leave the cassette toilet clean and dry so it is ready for the next trip.
A little maintenance saves a very unpleasant job later
Cassette toilets aren’t particularly complicated devices. Most problems come down to seals becoming dry, mechanisms getting dirty, vents becoming restricted, residue building up inside the tank or small moving components no longer moving as they should.
Empty it before it’s completely full, use the correct chemicals, give it a proper clean occasionally and keep an eye on the seals, float and vent system.
Do that and a cassette toilet will generally provide years of reliable service while remaining almost completely unnoticed.
Which, when you’re talking about something containing 20 litres of human waste beneath your bathroom floor, is probably the highest compliment you can give it.
