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Composting vs separating
Strictly speaking, most van "composting" toilets are separating toilets: urine goes to one container, solids to another with a dry medium. True composting happens later, if at all. What matters for you is: footprint, seat height, emptying frequency, and whether you want a fan and an agitator.
The models compared
| Spec | Trelino Evo L | Nature's Head | OGO Origin |
|---|---|---|---|
| Dimensions (W×H×D) | 33 × 43 × 39 cm | — | — |
| Weight | 4.9 kg | 23 lb | approx. 28 lb |
| Urine container | 10 L (18–22 uses) | — | — |
| Solids | 10 L (11–20 uses) | approx. 60–80 uses (manufacturer) | — |
| Seat height | Normal (per manufacturer) | — | — |
| Dimensions (H×W×D) | — | 21 × 20 × 19 in | — |
| Liquid bottle | — | 2.2 gal | approx. 2.4 gal |
| Ventilation | — | 12 V fan, fuse included | — |
| Mixing | — | Spider-handle agitator | Electric motor (5 A, 2-min cycle) |
| Dimensions (D×W×H) | — | — | 15 × 16 × 18.5 in |
| Fan | — | — | 20 mA, always on |
| Best for | Light, compact separating toilet with standard seat height, no wiring needed. | Full-time living with an agitator and a vent fan. | Compact full-timers who prefer push-button mixing to a hand crank. |
Source: manufacturers' product pages (linked on each product card), checked 2026-11-14. “—” = not published on the page.
Trelino Evo L
Best for: Light, compact separating toilet with standard seat height, no wiring needed.
- Dimensions (W×H×D)
- 33 × 43 × 39 cm
- Weight
- 4.9 kg
- Urine container
- 10 L (18–22 uses)
- Solids
- 10 L (11–20 uses)
- Seat height
- Normal (per manufacturer)
- No fan as standard – ventilation kit sold separately
- Uses compostable bags; budget for consumables
Specs: manufacturer page, checked 2026-11-14. Based on manufacturer specs and public reviews – not a hands-on test.
Nature's Head
Best for: Full-time living with an agitator and a vent fan.
- Dimensions (H×W×D)
- 21 × 20 × 19 in
- Weight
- 23 lb
- Liquid bottle
- 2.2 gal
- Solids
- approx. 60–80 uses (manufacturer)
- Ventilation
- 12 V fan, fuse included
- Mixing
- Spider-handle agitator
- Needs a 12 V feed and a vent hose to outside
- Bulky for small vans – check the footprint
Specs: manufacturer page, checked 2026-11-14. Based on manufacturer specs and public reviews – not a hands-on test.
OGO Origin
Best for: Compact full-timers who prefer push-button mixing to a hand crank.
- Dimensions (D×W×H)
- 15 × 16 × 18.5 in
- Weight
- approx. 28 lb
- Liquid bottle
- approx. 2.4 gal
- Mixing
- Electric motor (5 A, 2-min cycle)
- Fan
- 20 mA, always on
- Electric agitator adds a component that can fail
- 12 V supply required
Specs: manufacturer page, checked 2026-11-14. Based on manufacturer specs and public reviews – not a hands-on test.
Trelino Evo S
Best for: Small vans and weekend use where every centimetre counts.
- Dimensions (W×H×D)
- 33 × 29.6 × 39 cm
- Weight
- 3.9 kg
- Urine container
- 4.5 L (9–11 uses)
- Solids
- 6.5 L (6–8 uses)
- Low seat
- More frequent emptying than larger models
Specs: manufacturer page, checked 2026-11-14. Based on manufacturer specs and public reviews – not a hands-on test.
How to choose
- Small van, weekends: a compact unpowered model like the Trelino Evo S – lightest, simplest, but low seat and frequent emptying.
- Full-time, want minimal odour management: a fan-ventilated unit with an agitator (Nature's Head or OGO), vented to outside.
- Middle ground: Trelino Evo L offers a normal seat height and larger containers without wiring; ventilation can be added.
Installation tips
- If it has a fan, run the vent hose by the shortest route to outside, and protect the outlet from rain.
- Secure the toilet to the floor using the manufacturer's brackets – it must not move under braking.
- Keep the liquid bottle accessible: you'll handle it most.
See the head-to-head in Trelino vs Nature's Head.
Frequently asked questions
Do composting toilets smell in a van?
Separating urine from solids is what prevents most odour. Models with a constantly running vent fan, plus a dry cover material such as coco coir, manage odour best. Smell problems usually come from liquid getting into the solids side.
How often do you empty a composting toilet?
Manufacturers give use estimates: e.g. Trelino lists 18–22 uses for the Evo L urine container and Nature's Head approx. 60–80 solid uses. The liquid side always needs emptying far more often than the solids.
Where can I empty a composting toilet?
Liquids are usually emptied into a regular toilet or a designated disposal point. Solids are typically bagged and disposed of according to local rules. Check the regulations where you travel.
Does a composting toilet need power?
Not necessarily. Trelino's base models need no wiring. Nature's Head and OGO use a 12 V vent fan, and OGO also uses an electric agitator.
Spotted an outdated spec? Tell us.