Why Does My Composting Toilet Smell? Causes and How to Fix It
- johnmorley83
- Jun 23
- 3 min read
Composting toilets have become increasingly popular with motorhome, campervan and boat owners looking for a more natural alternative to traditional chemical toilets. They avoid harsh chemicals and work by encouraging a natural breakdown process.
When working correctly, a composting toilet should have very little smell. However, many owners find that occasionally their toilet does start to produce unwanted odours.
The reason is simple: a composting toilet is a living system. It relies on the right balance of moisture, airflow and natural biological activity. When that balance is right, waste breaks down naturally. When the balance is wrong, smells can appear.
Why composting toilets can smell
One of the biggest causes of smells is too much moisture. Composting toilets rely on separating liquid and solid waste because excess liquid prevents the composting process from working correctly.
This is why diarrhoea can be a particular problem for composting toilets. Loose stools add a large amount of extra moisture into the solids container and can quickly upset the balance required for effective composting. If this happens, the toilet may need additional dry material, cleaning or emptying before the natural process can restart.
Diet can also make a difference. Human waste varies from person to person, and what we eat can affect both the smell produced and how easily waste breaks down. This is one reason why two people can use exactly the same composting toilet and have very different experiences.
Why does the urine container smell?
One of the most common sources of composting toilet smells is actually the urine container, not the solids.
Fresh urine normally has relatively little smell, but when it sits it starts to break down and can produce a strong ammonia odour.
Over time, the urine container and pipework can also develop a hard mineral build-up often known as urine scale. This looks similar to limescale and can trap smells, meaning your toilet may still smell even after it has been emptied and rinsed.
Simply washing the container with water is often not enough to remove these deposits, which is why regular cleaning is important.
Don’t kill the process your toilet needs
When a composting toilet starts to smell, many people instinctively reach for bleach or a strong antibacterial cleaner.
Unfortunately, this can work against the toilet.
Composting relies on natural biological processes. Products designed to kill bacteria can interfere with the breakdown process and stop your toilet working as effectively.
The solution is not to stop nature — it is to help nature work better.
How Solbio Compost Toilet Cleaner helps
Solbio Compost Toilet Cleaner has been created specifically for composting toilets.
Using plant-based ingredients, Solbio supports the natural breakdown process rather than disrupting it. It helps accelerate composting, removes urine scale deposits that can cause lingering smells, and keeps your toilet working as intended.
It is ideal for regular cleaning of the toilet bowl, separator, urine container and other areas of your composting toilet while protecting the natural balance inside.
A clean composting toilet is not about killing everything inside it — it is about creating the right environment for nature to do the work.
Thinking of buying a composting toilet?
Many people consider switching to a composting toilet because they dislike the smell and chemicals associated with traditional cassette toilets.
But often the problem is not the toilet — it is the chemical being added to it.
Traditional blue toilet chemicals are designed to slow down natural processes and preserve waste until the cassette is emptied. This can leave many people thinking the only solution is to replace their toilet completely.
However, a standard cassette toilet, such as a Porta Potti, can work in a very different way.
By replacing traditional chemical toilet fluids with Solbio Original Toilet Fluid, you allow waste to break down naturally rather than preserving it.
Solbio Original Toilet Fluid uses plant-based ingredients to encourage the natural breakdown of waste, helping create many of the benefits people are looking for when they consider switching to a composting toilet — including a fresher, more natural toilet experience.
For many motorhome, campervan and boat owners, changing what goes into the toilet can transform the toilet they already have — without spending hundreds or thousands of pounds replacing it.
Before investing in a new composting toilet, it may be worth trying a different approach first.
Keeping your toilet naturally fresh
Whether you use a composting toilet or a traditional cassette toilet, the principle is the same.
Nature already knows how to break down waste. The key is creating the right conditions and avoiding products that prevent that natural process from happening.
Solbio helps keep your toilet fresh by working with nature — not against it.
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