Thetford's £420 separating kit changes the cassette chore, and a microwave toilet is next

Emptying a toilet cassette is the one job in a campervan that nobody volunteers for. You wheel the tank across the site, hold your breath, tip, rinse, add the blue stuff, wheel it back. A separating toilet promises to swap that for a smaller, drier routine: a tank of urine and a bag of solids, no flush water, no chemicals. Thetford now sells a kit that turns its own C220 and C260 cassette toilets into exactly that, Dometic has shown rival kits for Thetford models, and HMT Huamao Tech has shown a toilet that microwaves waste into ash. None of them makes the chore vanish. They change what the chore is, and that change suits some people far better than others.

What a separating toilet is, and what it is not

Thetford's own explainer draws the line plainly: a separating toilet simply separates liquids from solids, and no composting happens in the toilet itself. That matters because the two get muddled in conversation. A composting toilet is trying to break solids down over weeks. A separating toilet is only trying to keep the two streams apart, because the familiar chemical-toilet smell comes mostly from liquids and solids sitting together in the wet. Keep them apart, keep the solids dry, move the air, and the smell drops sharply.

So a conversion kit is not turning your Thetford into a garden composter. It is replacing the flush-and-cassette arrangement with a urine tank and a dry bucket for solids, and leaving you to deal with each one separately.

The cassette routine as it stands

Before judging the alternative, be fair to the cassette. Thetford describes the cassette toilet as a lightweight toilet with a removable waste-holding tank, and says that when the waste holding tank is full, it needs to be emptied at designated disposal points which are connected to the sewage system. For a couple on a site, that typically means a trip to the chemical disposal point every few days.

The routine around it is where the cost and effort hide. Thetford recommends a tank treatment product, and says that after emptying you rinse the tank and add fresh additive and water. Then there is the flush water itself, drawn from your fresh tank every time you press the button.

None of that is a flaw. It is a mature, well-supported system, and Thetford's C220 waste tank comes with a handle and wheels for the walk to the disposal point. Thetford says designated disposal points are found at most campsites and motorhome sites and at certain road stops, and that its toilet additives include septic-tank-safe and biodegradable products. If you tour from serviced site to serviced site, the cassette is a solved problem. The case for separating starts when you are away from those points, short of water, or simply tired of the smell and the chemicals.

Thetford's own kit for the C220 and C260

The interesting part of this story is that the maker of the cassette toilet now sells the conversion itself. Thetford's Cassette Toilet Separation Kit fits the C220 and C260, and at Jacksons Leisure it was £419.95 including VAT and in stock on 6 October 2026. Thetford's own UK site gives a recommended retail price of £705.00, so that is well below list; dealer prices move, so treat it as a guide rather than a promise.

What you get

The kit needs no flushing water, has a 7 L solid-waste bucket and a 7.5 L urine tank, works with Thetford's ventilator kit for active ventilation, and weighs 3.5 kg, according to Jacksons. It comes with a mechanical urine level indicator (SK220) or an electrical one (SK260), and there is a ceramic-bowl version (SK260CB). The level indicator is the small feature you will care about most, because a urine tank with no warning is a urine tank you will overfill once and never forget.

Three and a half kilos is about three and a half bags of sugar, so the kit itself is not a payload worry. If your payload is tight, ask the retailer how much the parts that come out weigh against the kit that goes in.

Check which toilet you have first

The kit is for two models only, so do this before you spend anything. Check the model number on your toilet or its documentation, and if it is anything other than C220 or C260, Thetford's kit is not the answer, though Dometic's may be (more on that below).

Fitting and ventilation

Thetford says the kit is designed for DIY enthusiasts and is easy to install, and it is designed around the existing C220 and C260, so you are not cutting a new hole for a whole new toilet. One thing to know before you start: Thetford says that once the bracket is removed you cannot return to the original toilet, and if you might want to switch back it recommends a complete S220 or S260 separation toilet instead.

The ventilator kit is the part to think hardest about. Active ventilation means a fan drawing air out of the solids compartment and away from the van, and a fan needs a power feed (Thetford mentions a wiring harness for some models) and somewhere for the air to go. Jacksons lists Thetford's ventilator kit separately at £99.95 including VAT, so budget for it on top of the £419.95, and ask whether your existing cassette vent route can be reused before you order. Thetford notes that if you have an S220CW and want to add the optional ventilator kit, you need an extra wiring harness (spare number 200963), and that with a C260CWE it advises getting a full S260CS toilet instead, since that has the correct wiring harness inside.

Living with a separating toilet

This is the real comparison, because the kit does not remove the chore. It replaces one big wet job with two smaller dry ones.

The urine tank

At 7.5 L the urine tank is the part you will empty most often. An adult produces somewhere around a litre and a half of urine a day, so two people would fill it in roughly two to three days, less if you drink a lot of tea. The good news is that a tank of urine is light, does not smell much while fresh, and can be carried in one hand. The habit that works is emptying it early and rinsing it, rather than running it to the indicator every time.

The solids

Solids go into the 7 L bucket. Thetford sells Separation Toilet Waste Bags made from recycled plastic and an optional Separation Toilet Drying Agent, which absorbs liquid and leaves drier, easier-to-handle waste. Ask the retailer what is in the box and what you will need to keep buying. A 7 L bucket for two people will want emptying somewhere between a few days and a week depending on use, and emptying it means tying the bag and taking it to a bin. For some people that is far less unpleasant than a cassette. For others, handling a bag of solids is exactly the thing they wanted a flushing toilet to avoid. Be clear with yourself which camp you are in before you spend £420.

Smells

Kept apart and kept dry, the two streams smell far less than a cassette, and with a fan running the bathroom should smell of very little. The two places smell comes back are a urine tank left too long and a solids bucket that has got wet. Both are habits, not design flaws.

Water and chemicals

Here the separating toilet wins outright. Thetford's cassette routine calls for fresh additive and water in the tank after each emptying, and that is before the flush water you use through the day. The separation kit uses no flushing water at all. If you tour off grid with a small fresh tank, that is a meaningful extension to the days between fills, and the chemical shopping stops.

Where the waste goes

Thetford says urine can simply be poured into any regular toilet and solid waste can go in with regular household waste, but always check local regulations to be sure. Thetford's advice for cassettes is the designated disposal point, and the sensible move with a separating toilet is still to ask each site office what they are happy with for the urine tank and for bagged solids before you need to know. Build that question into your arrival routine and the conversion stops being awkward.

Dometic's kits at Düsseldorf

Dometic showed kits at Caravan Salon Düsseldorf 2026 (28 August to 6 September) that convert cassette toilets into separating toilets, and its show page describes them as available for all common Thetford models. That is the line that widens the field, because Thetford's own kit stops at the C220 and C260. If your toilet is another Thetford model, Dometic's kit is the one to watch.

Dometic's price and UK availability for those kits are not confirmed. Ask a dealer for the tank sizes and weight before comparing them line by line with Thetford's. If you can live with the cassette a little longer, it may be worth waiting to see what arrives and at what price; if you have a C220 or C260 and want the change now, Thetford's kit is in UK stock.

The money

At £419.95 the Thetford kit is a real spend on a toilet you already own and which already works. Whether it pays back depends on two things.

• What you spend now. Add up a season of tank treatment and the other cassette care products you buy. Only you know that figure; some owners spend very little, some spend a surprising amount.
• What you will spend instead. Waste bags and the optional drying agent are not free either: Thetford's UK site gives recommended prices of £7.00 for its waste bags and £17.59 for its drying agent, so check how many uses each pack gives. The chemical bill goes to zero; the consumable bill does not.

Until you know how long a pack of bags and drying agent lasts you, it is hard to say whether the kit pays for itself in consumables, so the case rests on the things that are hard to price: no chemical handling, longer between water fills, less smell, and the option to stop at places without a disposal point. If none of those is a problem for you, keep the cassette and the £420.

Who should keep the cassette, and who should convert

Keep the cassette if

• You tour from serviced site to serviced site and the disposal point is a short walk.
• You would rather empty one tank into a drain than handle a bag of solids.
• Your toilet is not a C220 or C260 and you would rather wait for Dometic's kit than fit a different toilet.
• You are happy with the chemical routine and it is not costing you much.

Convert if

• You spend a lot of nights off grid or at stopovers without a chemical disposal point.
• Your fresh tank is small and flush water is eating into it.
• Smell from the cassette, especially in summer, is what you dislike most.
• You want to stop buying and carrying tank chemicals.
• You already have a C220 or C260 and £420 is acceptable for the change.

What's next: the microwave toilet

If separating is the practical step, the microwave toilet is the glimpse of what might follow. According to promobil, the X Sani from HMT Huamao Tech reduces waste to ash with microwaves; it runs at 48 V, uses about 1 kWh per kilogram of contents (solids and liquids together) and draws up to 56 A at peak. The appeal is obvious: no cassette, no urine tank, no bags, just ash to dispose of. The catch is electrical, and it is worth working through.

Why 48 V

Most UK campervans run their leisure systems at 12 V. The X Sani wants 48 V, which means either a 48 V battery bank, which exists in the leisure world but is not the norm, or a converter stepping up from 12 V. At 56 A peak on 48 V the toilet is drawing about 2.7 kW (48 V multiplied by 56 A is 2,688 W), which is roughly the power of a domestic kettle running flat out. Pulled from a 12 V bank through a converter, that same power would mean more than 220 A on the 12 V side (2,688 W divided by 12 V is 224 A), with the thick cables and heavy fusing that go with it. Running at 48 V quarters the current for the same power, which is why the maker has gone that way.

What a kilowatt-hour per kilogram means in a van

A 100 Ah 12 V leisure battery holds about 1.2 kWh when full (12 V multiplied by 100 Ah is 1,200 Wh), and you will not get all of that out. So, in round terms, each kilogram the toilet processes costs you most of a 100 Ah battery's worth of energy, before any conversion losses. On hook-up that is nothing. Off grid it is a serious draw; a 200 W solar panel on a good summer day in the UK might make around a kilowatt-hour, and in winter nowhere near. This is a toilet for vans with large battery banks and mains access, not for a weekend camper with a single battery.

Price, fitting and availability

Its German price has not been set, but it is said to come in below the Cinderella incineration toilet, which auto-medienportal puts at about €4,000. What that is in pounds depends on the exchange rate on the day, but it is in a different league from a £420 kit. Fitting an X Sani means drilling holes, and UK availability is not confirmed. According to promobil, the ash can simply go in the household bin; how often it needs emptying is a question for HMT, so treat this as a product to follow rather than one to budget for.

The bottom line

Thetford's separation kit is the only one of the three confirmed on sale in the UK today, it is in stock at around £420, and it does what it says: no flush water, no chemicals, a urine tank you empty often and a solids bucket you bag and bin. It is not a way to stop dealing with waste, it is a way to deal with it differently, and that trade suits off-grid and water-conscious tourers best. Site-to-site tourers with a disposal point nearby lose little by staying with the cassette. Dometic's kits widen the choice to other Thetford models once a UK price appears. The microwave toilet is a fascinating signpost, but its 48 V, kilowatt-hour-per-kilogram appetite keeps it in the future for most of us.