Composting Toilets: The Complete Guide
In short
A composting toilet is a waterless toilet that diverts urine into a sealed bottle and lets solids break down in a carbon-rich material like coco coir, so there's no smell and nothing to flush. It needs no chemicals or sewer connection, which makes it a natural fit for campervans, RVs, boats, tiny homes and off-grid cabins.
A composting toilet is a waterless toilet that separates liquid from solid waste and uses natural decomposition, not chemicals or a sewer connection, to break down what you put in it. Urine is diverted into a sealed bottle while solids drop onto a carbon-rich material such as coco coir and slowly compost, so there’s no smell and nothing to flush. They’re popular in campervans, RVs, boats, tiny homes and off-grid cabins where running water and plumbing aren’t available.
How does a composting toilet work?
A composting toilet works in two streams. A urine diverter at the front of the seat sends liquid into a separate bottle, while solids fall into a bin filled with a carbon medium like coco coir. Keeping the two apart is the whole trick, odour is created when urine and solids mix, so separating them keeps the toilet smelling earthy at worst. Solids are mixed (on the Cuddy, with a built-in agitator) to add air and dry the material so it begins to compost down. Read the full step-by-step: How Does a Composting Toilet Work?
Types of composting toilet
Urine-diverting (separating)
Splits liquids and solids for odour-free, low-maintenance use. The most common type for vans and boats, like the Cuddy and Cuddy Lite.
Self-contained vs central
Self-contained units keep everything in one body, ideal for vehicles. Central or batch systems sit below a larger building, better for cabins and tiny homes.
Electric vs non-electric
Electric models add a 12V fan for airflow. Non-electric models like the Cuddy Lite need no power, venting or plumbing at all.
Composting vs dry-flush
Not all waterless toilets compost. Dry-flush toilets like our S1 seal each use in a bag instead. Quick and tidy, but they do not break waste down.
Composting toilet vs chemical, dry-flush & traditional
Composting toilets need no water and no chemicals; chemical (cassette) toilets need both and must be dumped at a station; dry-flush toilets seal waste in a bag; and traditional toilets need plumbing and a sewer or holding tank. For off-grid and mobile use, composting and dry-flush are usually the most practical. See the full comparison table → Composting vs Chemical vs Dry-Flush vs Traditional
How much does a composting toilet cost
| Option | Typical upfront | Ongoing cost |
| DIY / bucket system | $50-$150 | Coir + bags, very low |
| Portable composting (Cuddy Lite) | $650 | Compostable bags + coir |
| Self-contained composting (Cuddy) | $850 | Coir refills; minimal 12V power |
| Premium / electric units (market) | $900-$1,200+ | Coir; power for fan/heater |
Against a chemical toilet, the saving over time comes from skipping deodorising chemicals and dump-station fees. Full breakdown: Are Composting Toilets Worth It?
Do composting toilets smell?
No, a properly set-up composting toilet does not smell. Because urine is diverted away from solids, there’s nothing to produce the usual toilet odour; the composting material smells earthy, like a forest floor. A fan and carbon filter (on vented models) pull any trace odour away from the seat. More on odor control → Do Composting Toilets Smell?
Who composting toilets are for?
Campervans & RVs
No black tank and no dumping. Empty it on your own schedule, wherever you are.
RV guide →Boats
No through-hull and no holding tank, and legal to use in more waters than a flushing head.
Tiny homes & cabins
Full bathroom comfort, completely off-grid, with no plumbing to install.
Home backup & off-grid
A reliable toilet for when the water or power is out, ready whenever you need it.
Off-grid options →The CompoCloset Range
Better toilets for people & the planet
Three ways to go waterless, pick the one that fits how you travel and live.
Do composting toilets smell?
No. When used correctly a composting toilet doesn’t smell, because urine is kept separate from solids. The composted material smells earthy rather than unpleasant, and vented models add a fan and carbon filter to keep air moving away from the seat.
How often do you empty a composting toilet?
It depends on use. As a guide, two people in full-time use empty the urine bottle every few days and the solids bin roughly every 2-3 weeks. Both lift straight out. No tipping or disassembly.
Do composting toilets need water or plumbing?
No. Composting toilets are completely waterless and need no plumbing or sewer connection, which is what makes them ideal for vans, boats, tiny homes and off-grid cabins.
Do you need electricity?
Only some models. Vented composting toilets use a small 12V fan for airflow, but non-electric options like the Cuddy Lite need no power, venting or plumbing at all.
What do you put in a composting toilet?
A carbon-rich material such as coconut coir or wood shavings. It kick-starts composting and absorbs moisture. No chemicals or special additives are needed.
