Composting toilet with urine diverter for small spaces

If your top priority is a composting toilet that doesn't smell and fits in a small space, I'd focus on a urine-diverting design with a well-sealed solids container and a reliable ventilation fan. Separating urine from solids is one of the biggest ways to reduce odor, but ventilation, correct use, and maintenance matter just as much.

For a tiny house, van, cabin, RV, or off-grid bathroom, I'd compare compact urine-diverting toilets rather than conventional composting toilets, which can take up more space.

My top 3 picks

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(Best for a tiny bathroom)

1. Separett Tiny

$999–$1,049

This is my first choice if space and odor control are your biggest concerns. It separates urine, uses a ventilation fan, and has a compact design. It doesn't require bulking material or manual mixing. The solids container needs regular emptying, roughly weekly for two full-time users.separett.com+2

Best for: a tiny home, small cabin, or permanent off-grid bathroom.

View Separett Tiny options

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2. OGO Origin Composting Toilet

Compact premium alternative

The OGO Origin has a reported 15 × 16-inch footprint, urine diversion, powered mixing, and a ventilation fan. Its electric agitator avoids the manual cranking required by some competing models.www.museituppublishing.com+1

Best for: a tight van or tiny-house bathroom where you want easier day-to-day operation.

View OGO Origin

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3. Nature's Head Self-Contained Composting Toilet

$965–$1,035 approximately

A well-established choice for RVs, boats, and cabins. It diverts urine into a separate container and uses a 12V fan to vent the solids chamber. You'll need to turn its mixing handle after solid waste use, and empty the urine bottle regularly.wildoaktrail.com+1

Best for: a self-contained installation where you don't want a urine drain line.

View Nature's Head

Which is least likely to smell?

My pick is the Separett Tiny for a permanent small bathroom, provided you can install its vent and urine drainage correctly. The OGO Origin is worth considering if its smaller footprint fits your layout better. Neither can honestly be guaranteed odor-free under every condition.

For the best odor control, prioritize these details:

• Continuous ventilation: exhaust outdoors, with the fan running as specified by the manufacturer.
• Reliable urine separation: urine buildup or a blocked drain can cause strong ammonia odors.
• Easy cleaning: keep the diverter and bowl clean, and empty liquid containers before they overflow.
• Proper waste handling: a composting toilet doesn't necessarily finish composting waste inside the unit; follow the manufacturer's disposal instructions and local rules.

One question so I can narrow it down

Where will you install it?

1. Type of space

Tiny house or cabin

RV or camper van

Small indoor bathroom in a home

Boat or off-grid shelter

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2. Can you run a urine drain to an approved collection or disposal point?

Yes

No, I need a built-in container

Not sure yet

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3. How many people will use it?

One person

1–2 people full-time

3 or more people

Occasional or guest use

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4. Budget

Under $700

Up to $1,100

Up to $1,500

Best odor control regardless of price

[Find my best match]

For a small bathroom, tiny home, or van setup, a urine-diverting dry (composting) toilet is the absolute gold standard for keeping odors away. By separating liquids from solids immediately, you prevent the chemical reaction that creates ammonia and traditional sewage smells.

The best compact options on the market balance a small footprint, reliable odor control, and easy waste management:

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• Footprint & Build: Highly space-efficient with a modern design that can mount flush against a wall while still allowing full lid access.
• Odor Control: Features a 12V internal fan paired with a reusable carbon filter. It also includes a digital "pee full" LED indicator light so you never risk an overflow.
• Why it's great: It has one of the largest drop zones for its size and an internal agitator to help condense and dry solid waste. Check details and pricing directly via the Nomadic Supply Company Cuddy Listing.

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• Footprint & Build: Exceptionally compact and fully self-contained, engineered specifically for tight spaces like vans, small RVs, and tiny house bathrooms.
• Odor Control: Excellent urine-diverting trap-door system that pairs with a standard external ventilation hose.
• Why it's great: Unlike most compact toilets that require hand-cranking to mix solids, the OGO features a unique electric 12V motor agitator that cycles with the push of a button.

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• Footprint & Build: Extremely lightweight and shaped like a small box (the 'S' size is roughly the footprint of a small crate), making it ideal for micro-bathrooms.
• Odor Control: Relies on instant separation, a tight-sealing membrane lid, and absorbent litter (like hemp or sawdust) rather than constant electric fan dependence, though custom venting can be added.
• Why it's great: It is completely waterless, chemical-free, and super easy to tuck away or remove. View specifications on the Trelino Official Store.

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• Footprint & Build: Built into a standard Eurobox format (40 × 30 cm), making it one of the absolute smallest and most low-profile separation toilets available.
• Odor Control: Uses hemp-based litter to absorb moisture and neutralize smells immediately.
• Why it's great: It requires zero electricity or plumbing hookups, making it a budget-friendly and ultra-portable choice for tight spaces. Check out specs on the BOXIO Store.

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• Footprint & Build: Sun-Mar's smallest model yet, featuring a sleek, modern European profile with an elongated seat for household-level comfort.
• Odor Control: Uses a quiet, low-wattage 12V DC ventilation fan to continuously draw air through the unit and vent it outside.
• Why it's great: It feels the most like a "real" residential toilet while keeping a narrow, portable frame. See details on the Wild Oak Trail Sun-Mar GTG Page.[1][2][3][4]

To help narrow down which unit fits your bathroom best, let me know:

• Do you have access to 12V or 110V electricity for a built-in ventilation fan?
• Are you able to install a small vent hole through the wall or floor/roof to the outside?
• What is the exact space clearance (width/depth) you have available in the bathroom?

If you have a small bathroom and want a composting toilet that separates urine while keeping odors under control, I’d focus on compact, urine-diverting toilets with a continuous exhaust fan. The best models keep liquid and solid waste separate, draw air through the solids chamber, and vent that air outdoors. That combination can keep odors very low when the toilet is installed and maintained correctly.separett.com+3

My top three to compare are the Separett Tiny, OGO Origin, and Sun-Mar GTG. They offer different trade-offs in footprint, maintenance, and price.

Best compact urine-separating toilets

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1. Separett Tiny

(Best for small bathrooms)

$999–$1,070

A compact, conventional-looking toilet designed specifically for tight spaces. It separates urine into a built-in tank or drain connection, collects solids in a bag-lined container, and uses a continuous fan for ventilation. No hand-crank mixing or composting medium is required.separett.com+1

Trade-off: The internal urine tank needs frequent emptying—potentially several times a week for two full-time users.

Best if you want a clean, simple, low-fuss installation.

View Separett Tiny options

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2. OGO Origin: Top-Rated Composting Toilet for RV & Van Life

(Best for the tightest footprint)

$984.99

The OGO Origin has an approximately 15 × 16-inch footprint, a separate 2.4-gallon urine container, a powered solids agitator, and a vent fan. Its push-button mixing mechanism avoids the side-mounted hand crank found on some competitors.www.onegreenplanet.org+2

Trade-off: You need electricity, and the urine container may need emptying every couple of days with two people.

Best if every inch matters and you prefer modern styling.

Buy from OGO

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3. Sun-Mar GTG Urine Diverting Composting Toilet

(Best lower-cost option)

$639.00

The GTG separates liquids and solids, has a compact design, and offers a removable upper section that helps with cleaning and emptying. It's worth considering if you want a less expensive electric unit.www.onegreenplanet.org+2

Trade-off: Smaller waste capacity means more frequent emptying for full-time use.

Best for a small cabin, occasional-use bathroom, or budget-conscious project.

View at Blackwater Depot

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4. Nature's Head Composting Toilet

$965–$1,035

A well-established self-contained option with a urine diverter, vent fan, and manual mixing handle. It is particularly worth considering for full-time use in a cabin, RV, or boat.www.onegreenplanet.org+1

Trade-off: The side handle needs clearance, and the unit is bulkier in some layouts than the OGO.

Best if durability and longer solids-emptying intervals matter more than the smallest possible footprint.

View at The Cabin Depot

How to keep odors away

Even a good toilet can smell if ventilation or waste separation is compromised. Prioritize these features:

• Continuous exhaust fan: Vent the air outdoors through a properly installed wall or roof duct.
• Reliable urine separation: Keep liquid from entering the solids compartment.
• Accessible waste containers: Make emptying easy enough that you won't put it off.
• Easy cleaning: Keep the urine diverter and bowl clean to prevent residue and ammonia smells.
• Power backup, if off-grid: Have a plan for fan operation during outages.

One important distinction: these units generally collect and dry waste rather than finish composting it inside the toilet. You'll still need to dispose of the waste according to local rules.separett.com+3

Which one fits your bathroom?

I can narrow this down to the best model for your setup with one detail: Is this for a permanent home bathroom, a tiny house/cabin, or an RV/van?

That matters because a permanent bathroom may accommodate a urine drain connection, while a self-contained tank is often more practical in a mobile space.