Common Compost Toilet Smells and How To Fix Them

Even the best compost toilets can smell sometimes, but the fix is usually simple. Whether you’re a beginner or a seasoned user, this quick guide covers the 4 most common odor issues and how to solve them fast. After years in our skoolie, summer humidity still caught me off guard. If your toilet suddenly starts to stink, this guide has your back.

In this guide we will cover:

• Identifying the source
• Urine odors
• Stinky poo smells
• The case for ventilation fans

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Identifying the Source

Start with the sniff test – definitely the least pleasant part of this process. Narrowing down where the smell is coming from will help you quickly identify the culprit and get right to the fix.

• Liquids Jug
• Solids Bin
• Somewhere else/I’m not sure

If you’ve narrowed it down, click jump right to those smells. Otherwise, keep reading

Problem Smells and How to Fix Them

Strong Urine Smell from the Liquids Jug

Cause: Urine odors vary from person to person and can change based on your hydration level, medications, and other factors.
The Fix: Add a little vinegar to your liquids just or use a vinegar spray on the diverter after use. Vinegar helps neutralize the smell of pee.

Ammonia smell from the Solids Bin

Cause: Urine getting into solids bin
The Fix:

1. Ensure your diverter is working properly. Some toilets have flaps and moving parts that when clogged, allow the liquids to run over into the solids bin. Dig around to find the clog and remove it. Psst! The Throne diverter intentionally has no moving parts or nooks & crannies.
   
2. Check your body positioning. Compost toilets with small bowls can easily allow urine to flow over the divider into the solids bin. If sitting, ensure that you are far enough forward to direct your pee in the right funnel. Some toilet designs and body geometry means perching towards the front – not the Throne. Men may need to sit to use some diverters to ensure the liquids go where they need to, though the Throne diverter is deep and steep enough that those who are equipped, may stand.
   
3. Teach kids how to check their body position and educate them on the importance of getting their pee in the right hole. Make it a game!

Diverting your liquids, while not necessary, makes odor management much easier. When liquids get into the solids bin, it causes more odors. You can simply add more cover material but this is going to mean more frequent emptying which is what you were trying to avoid by getting a urine diverting toilet in the first place.

For me, getting the urine in the wrong place was the most common cause of smells with other compost toilets I owned before getting the Throne. The shallow bowls just make it so easy for an enthusiastic pee to swirl around and flow over. And ask me sometime about digging wet TP out of a hidden nook where it got jammed when a kid didn’t use the flap correctly on our old toilet. Ugh!

Stinky Poo SMell

Cause: Too little cover material
The Fix: Add more cover material. Using too little cover material is a common mistake with new users. You want enough to smother any odors and it needs to coat the “deposit” you just made.

Cause: Too much moisture in the solids bin
The Fix: 

1. If the moisture is caused by urine getting in the solids bin, see previous points on that topic. 
2. If you’ve made certain this isn’t the cause, you may need either more cover material or dryer cover material. Generally, cover material should be slightly damp so that it is sticks to the “pile” yet dry enough that it is able to take up additional moisture from the toilet contents. 
3. If you are confident that you are adding plenty of cover material and you are in a warm, humid climate, this may indicate the need for dryer cover material. This tends to change with the seasons.

Cause: Too much toilet paper in solids bin
The Fix: Try putting your TP in another trash bin to make it easier for cover material to cover. Everyone has their own TP management system but it’s generally agreed in the community that you want to minimize how much of it goes in the solids bin. The problem is just that it’s so fluffy it makes it hard for the cover material to get to the poo and suppress the smell. 

Cause: You just pooped
The Fix: Smells will occur during use and generally they go away once the fresh deposit is covered. However, a ventilation fan can reduce smells during use by whisking it away before it rises to your nose. Check out the Throne Vent Kit to add one to your DIY compost toilet.

Smells from an Empty toilet

Cause: Residue from spills and splashes
The Fix: Occasional deep cleans are necessary. Give the toilet a good wipe-down with a vinegar solution, soak the diverter in vinegar or a diaper detergent to remove any lingering buildup. The Throne has limited spaces for gunk to hide and is easy to wipe clean, however, if your toilet has lots of nooks and crannies, a deep clean might be harder to accomplish. 

I once took a compost toilet to a car wash and sprayed it down with the pressure washer. My recommendation on this is mixed: it got cleaner but what do you think all that dirty toilet spray bounced back on?

Ventilation Fan

You don’t need a ventilation fan on a properly managed compost toilet. But let me make the case for why I think you should install one anyways. Do you do everything exactly right 100% of the time? How about the other folks that will be using your toilet?

A vent fan gives you a little lee-way: it removes any odors produced during use, and buys you some forgiveness if the cover material levels aren’t exactly right, a guest pees in the solids bin, or the summer humidity changes in your toilet take you by surprise. You can run the tubing out your wall, floor, or roof to send the stink packing. Check out the Throne Vent Kit here.

Keep your compost toilet smelling fresh

A compost toilet should be a low-maintenance, odor-free solution—but when something smells off, it’s usually an easy fix! By identifying the source and making small adjustments, you can keep your toilet fresh and avoid the “ick”. Whether it’s tweaking your urine diversion, using the right cover material, or adding a ventilation fan for extra peace of mind, a few simple changes can make all the difference. With this guide as your reference, you’ll have any issues that arise fixed in no time!

Learn More

• Want more Tips & Tricks on how to clean, empty, and maintain your toilet? Read this article.
• The Humanure Handbook by Joseph Jenkins is the widely recognized definitive word on composting your toilet contents. 
• The Compost Toilet Handbook by the same author gives in depth advice about living with and managing a compost toilet.

If you’re feeling like a slave to the tyrant turd in your life (your toilet, not your partner!), consider switching to the Throne – a compost toilet designed to overcome years of hassle experienced by our team with their previous toilets. We used our over 34 years of cumulative experience to build a better toilet. Throne is the simplest, most effective composting toilet designed for maximum freedom and minimal hassle. No proprietary parts. No complicated mechanisms. Just clean, odor-free performance.

Have any questions? Drop a comment below or reach out to us at support@thronecompostingtoilet.com and we are happy to help.