How, Where and When to Empty a Composting Toilet

If you travel in a motorhome, are into vanlife, off-grid adventures, or just tired of chemical toilet chaos, portable composting toilets are the perfect solution for your caravan, tiny home, or garden studio.

No black tanks. No harsh chemicals. No unpleasant whiffs. Just a clever, waterless system that provides relief without the mess.

Still, one question always comes up:

“How do you empty a composting toilet?”

Here’s everything you need to know about when, where and how to empty your composting toilet. And the best part? It’s simpler than you think.

How a Composting Toilet Works

Composting toilets are urine-diverting toilets. That means liquids and solids are kept in separate containers, which makes things a whole lot easier and much less smelly.

• Solids go into a container with browns: a composting medium like coconut coir or sawdust. This helps dry things out and starts the composting process.
• Liquids are collected in a removable bottle that gets emptied more frequently.

If you're using a toilet like Cuddy, it will have an agitator to help mix the solids and medium after each use. Toilets like Cuddy Lite skips the agitator for a more lightweight design, so you'll simply layer more compost medium on top after each use.

When to Empty Your Composting Toilet

Some benefits of portable composting toilets are that you don't have to empty them as often as you might think, you don't have to worry about emptying your black water tank, and you won't be using your precious water supply for a flush toilet.

This means you can be out longer and stay off-grid for extended periods with less of an environmental impact.

How often you need to empty it depends on the style and usage. Here’s a general guide for one person using the toilet from CompoCloset full-time:

Cuddy:
Solids: Every 2 to 4 weeks
Liquids: Every 1 to 2 days

Cuddy Lite:
Solids: Once a week
Liquids: Every 1 to 2 days

Since Cuddy Lite doesn’t have an agitator, solids build up a little faster.

Where to Empty Your Composting Toilet 

Now for the question of the hour: WHERE do you empty a composting toilet?

Disposal of Liquids

Let's start with the easy one: disposal of liquid matter. Your urine container can be emptied in various acceptable places, such as:  

• Public toilets at service stations, supermarkets, or town centres. Carry the container discreetly in a reusable bag and pour the contents directly into the toilet. Flushing as you pour helps minimise splashing.
• Your home toilet if you’re returning from a trip
• Campsite chemical disposal points. Many allow compost toilet liquids. Always check with the site manager.
• Grey water systems on private land with appropriate permissions. 
• On the ground. If you are wild camping (where permitted), always follow Leave No Trace principles. Avoid dumping near footpaths, waterways or anywhere people or wildlife could be impacted. 

Some places not acceptable are:

• Storm drains, kerbs or gutters
• Public rubbish bins
• Near water sources or food-growing areas
• Anywhere not specifically approved for liquid waste disposal

Disposing of Solids

Now for the one that takes a little more research than... number one. Where do you empty your composting toilet solids bin? Since there's human poop in there, there are some considerations to make before you empty it. 

Remember that even though your solids bin may look and smell like compost, it's not actually compost yet. The composting process for human poop takes up to six months, so until then, your solids are classified as non-hazardous human waste, similar to nappies or pet waste. 

Here are some general disposal options:

1. General Waste Bin:  This is the most common method for travellers. Double-bag the solids in a compostable or biodegradable liner and place in a regular bin destined for landfill. Tip:  If the council accepts nappies and pet waste, they will accept bagged humanure
2. Dedicated home compost system: If you have a garden compost setup, you can complete the composting process yourself. Use a separate, labelled bin that is not used for food-growing areas and give it at least six months to finish composting.
3. Campsites or eco-locations:  Some eco-conscious sites have their own composting systems and may accept solids from your portable toilet. Always ask permission first.

Do Not:
- Bury solids on public land or in woodland
- Dispose in green waste, food waste or recycling bins
- Use the compost on fruit or vegetable gardens before it is fully processed

What to do with Toilet Paper

You can put toilet paper in the solids bin, but if possible, separate it.

Even compostable toilet paper adds bulk and can wrap around the agitator in toilets like Cuddy, making cleaning more difficult and filling up the bin faster.

A better option is to:

• Place used toilet paper in a small airtight bin or separate compost caddy
• Line it with a compostable bag
• Dispose of it with your household waste

It’s simple, smell-free and extends the life of your solids container between empties.

Tips for Stress-Free Emptying

1. Carry a disposal kit: Include compostable bags, gloves, cleaning supplies, and a reusable bag for discreet transport of containers.
2. Check local guidance: Councils and campsites may have specific rules. Always ask if unsure.
3. Be discreet and respectful: Transport your liquids bottle in a reusable bag when taking it to be emptied. Ensure bags are sealed when disposing of solids in rubbish bins.

Emptying Your Composting Toilet is as Easy as 1, 2, 3

Emptying your composting toilet in the UK is easy once you know how.

• Liquids go into toilets, campsite disposal points, grey water systems, or responsibly on the ground
• Solids go into landfill-bound bins or a home compost system
• Toilet paper can be separated to extend the time between solids bin changes

These toilets are designed to simplify life on the road or off-grid. With the right setup, you can spend more time exploring and less time worrying about where the nearest chemical disposal point is.