Composting toilet for a caravan in Australia: the two clauses that actually apply, where the waste can legally go, and the real capacity (2026)

Most of what is written about composting toilets in Australia is written about houses, and the house rules are strict: a model has to be on a register, a council has to approve the installation, and a second approval lets you operate it. None of that machinery is written for a vehicle. So people move the question sideways, reasoning that a model good enough for a house must be fine in a van, and end up arguing about the wrong document. There are two documents that actually govern a toilet in a caravan or a motorhome, and neither of them has ever heard of a composting toilet.

The clause that governs a caravan

For a trailer with an aggregate trailer mass of 4.5 tonnes or less — which is nearly every caravan and camper trailer on Australian roads — the reference is the Commonwealth’s Vehicle Standards Bulletin 1, currently Revision 6. Toilets appear in clause 13.2.3, “Toilets, basins and sinks”, and the clause is three sentences long:

Toilets must not discharge directly onto the road. · Toilet closets must vent directly to atmosphere. · Tanks into which toilets discharge must contain non-inflammable and non-irritant chemicals to form an efficient deodorant and germicide.

Read it against a separating composting toilet and the first two sentences are easy. Nothing discharges onto the road; the unit is sealed and, in the installed models, actively extracted through a vent hose to the outside. The third sentence is the interesting one. It does not say every toilet must have a tank. It says that tanks into which toilets discharge must contain a deodorising, germicidal chemical — a sentence written in the era when the only option in a van was a cassette full of blue.

A composting toilet has no tank into which the toilet discharges. It has a solids bin with a bulking medium in it and a urine bottle you carry out. Whether clause 13.2.3 is satisfied by having no tank, or whether the clause simply does not contemplate the case, is not stated anywhere in the published material. That is the honest answer, and it is worth more than a confident one.

The clause that governs a big motorhome

Heavier motorhomes get inspected under a different book: the National Heavy Vehicle Inspection Manual, V3.2, whose Section 15 covers motorhomes, caravans and campervans. There the toilet appears as a reason for rejection, numbered 15.1.l:

Where a toilet or urinal is present a catchment tank (black water tank) is not fitted or the tank is not vented directly to the atmosphere

This is stricter than VSB1 and it is the sentence a motorhome owner should read twice. VSB1 conditions its chemical requirement on a tank existing. The NHVIM makes the absence of the tank itself the defect: toilet present, catchment tank absent, reject. Section 15 says nothing about discharge onto the road, nothing about chemicals, and nothing about venting the closet as opposed to venting the tank — and, again, nothing about what an inspector is supposed to do with a unit that was designed never to have a black water tank.

Two documents, two different logics, one gap in the middle. If your vehicle is a caravan or a light camper, VSB1 is your document and it is permissive by silence. If your vehicle is heavy enough to face an NHVIM inspection, 15.1.l exists and you should ask the inspecting station how they read it before you cut a vent hole in the floor.

The approval question nobody can answer for you

We went looking specifically for a government or manufacturer source stating whether a mobile composting toilet needs accreditation or council approval, and there is not one. VSB1 lists no accreditation requirement. NHVIM Section 15 does not mention approval. WA Health’s dump point guidance is about the facilities, not the fixtures. The Rota-Loo RL650 owners manual — a manufacturer document, and one of the more careful ones — states that local councils require AS/NZS 1546.2:2008 certification to approve a household installation, and is silent on the mobile case.

That silence is not the same as permission, and it is certainly not the same as prohibition. It means the question has been answered by custom rather than by a document. What is written down is the household framework, and a household framework attaches to a dwelling: the council approval process for an on-site system is triggered by a sewage management facility on a property, not by a fixture bolted to a chassis. If you want the register, the certificates and the two council approvals in detail, they are the subject of our guide to composting toilets in a dwelling; this page is about the vehicle.

Where the waste can legally go

This is the part that decides whether the toilet works for the way you travel, and it splits in three.

Liquids go to a dump point. The Western Australian Department of Health defines them precisely: public dump points are “public facilities provided by local governments to receive wastewater and liquid waste from caravans and other vehicles with mobile toilet and sanitation fixtures”, designed “to collect once-off discharge from such vehicles into a holding tank for collection, or into a reticulated sewer”. A urine bottle is exactly the once-off discharge the definition anticipates.

Solids have a documented path that surprises people: general rubbish. Compo Closet’s disposal guide for the Cuddy has the contents double-bagged in a compostable bag and put out with the household waste. Owners describe the same routine in their own words, and are matter-of-fact about it.

Burying is the option that is not universally available, and this is where a lot of van-life advice is simply wrong. The Rota-Loo manual describes the finished product being buried under 300 mm of soil, in a location not intended for food cultivation for three months — but that is the instruction for a household unit on your own land, where the material has actually had months to compost. On the road you are burying something much fresher, in a place someone else manages. François Peron National Park’s guidelines are blunt: “Burying toilet waste is not permitted.” The same guidance tells campers to bring and use a sealed-unit flushing chemical toilet or a sealed-unit composting toilet, and adds that “portable toilets that collect waste in a bag are not permitted” — which quietly rules out the lightest, cheapest, fan-free units in that park.

The capacity numbers, as published

Every manufacturer states capacity in a different unit, which is not an accident. Here is what the sources actually say.

Two things fall out of the table. First, the units are not comparable on solids at all: “60–80 uses” and “14.7 litres” and “6 buckets” are three different promises, and only one of them is a measurement. Second, on liquids they converge — 6.5 to 11 litres — and that is the number that actually sets your rhythm, because urine arrives at a fixed rate no matter how carefully you manage the solids.

What owners report, which is not the same

The gap between the brochure and the bin is the single most useful thing in the Australian forums, and it is not small.

Nobody in that thread disputes the toilet; they dispute the arithmetic. The same discussion produces a workable technique — start with dry coir and use less bulking medium than the instructions suggest — reported second-hand from a full-time traveller with three teenagers, which is the kind of claim to treat as a tip rather than a specification.

The urine bottle drives the day. Owners empty it daily and rinse it, and the constraint they describe is social rather than legal:

And the word “portable” in the search box does not survive contact with the products:

That is why the newer, smaller boxes — Cuddy, Trelino, the Joolca Gotta-Go with its bag cassette — keep coming up in threads that started out asking about a Nature’s Head. They are the answer to a different question: not how to stay out for a fortnight, but how to stop planning the route around dump points.

Against a cassette, honestly

The cassette is the incumbent and it is not a bad product. The comparison owners actually make is about where the vehicle goes.

One ExplorOz traveller sets out the whole trade-off with a number. He buries 95% of the black waste from his cassette because where he travels there are no dump points; traditionally that is about every four days, but by keeping urine out of the cassette and minimising flushing water he extends it to ten days without a problem. Separating the two streams is precisely what a composting toilet does by design. That is the real argument for one — not that it is greener, but that it decouples your itinerary from the map of dump points.

The counter-argument is equally real. You are trading a 20-minute chore every four days for a daily bottle, a fan that draws power, a vent hose through the floor or wall, and a bag of coir taking up locker space. If you tour between caravan parks, the cassette wins on effort. If you spend a week at a time where there is no dump point at all, the composting toilet is the one that keeps working — and in the national parks that require a sealed unit, it is on the approved side of the line while a bag-collection portable is not.

What we would check before buying

Ask the manufacturer, in writing, for the solids capacity as a volume, not as a number of uses, and compare it with the 14.7 litres Compo Closet publishes. Ask for the fan’s current draw in amps, and check it against your battery budget — 0.2 A continuous is about 4.8 amp-hours a day, which is not nothing on a small system. Measure the space where a cassette toilet lives now, because that is the constraint the newer compact units were designed around. And if your vehicle is heavy enough to be inspected under the NHVIM, ask the inspection station how they apply rejection reason 15.1.l to a toilet with no catchment tank before you spend $1,800.

For the household version of this decision — the register, the certificates, the two approvals and the greywater half of the problem that a waterless toilet does not solve — start with our dwelling guide.