Urine Diversion: The Secret to a Smell-Free Composting Toilet

When it comes to composting toilets, there's one often underestimated hero quietly working behind the scenes: the urine diverter. Whether you’re diverting urine into a urine bottle or outside into a drainage area, it may not sound glamorous, but the simple process of diverting urine away from solids is absolutely essential for keeping your composting toilet odor-free, efficient, and easy to maintain. 

In fact, separating urine from solids (or humanure) is the key to a fully functional composting system. 

Why Diverting Urine Matters

Composting toilets work by separating liquids and solids, allowing each to be handled in the most hygienic and efficient way possible. But why go through the trouble of diverting urine in the first place?

We’ve heard a lot of people say “A bucket will work just fine!” But unless you want a very stinky, sticky mess to deal with, a composting toilet is worlds better than a plain old bucket. 

When urine and humanure mix, things can quickly get… well, messy. Although not truly sterile as many people believe, urine is very low in pathogens. When fresh, urine contains high levels of nitrogen, which is great for fertilizing your garden, but not great for mixing with poo. 

When urine combines with solids, which are rich in carbon, the mixture creates the perfect environment for bacteria to thrive. And unfortunately, this bacterial activity leads to that dreaded rotten smell. 

This is the primary issue with traditional pit toilets, where both are combined in a single container. We’ve all been there at one time or another - slowly opening the door to a pit toilet at a trailhead, holding our breath, hoping that either the smell isn’t too dreadful, or we can hold our breath long enough to do our business and then escape back to fresh air again. 

On the other hand, composting toilets with a urine-diverting system, either into a urine bottle or another drain-away method like Cuddy, keep everything separate, which prevents the creation of foul odors. 

By removing the liquid portion, the remaining humanure dries out as it’s mixed in with organic matter, slowing decomposing and limiting bacterial activity. This dryness makes it easier for the solids to break down over time into usable compost without stinking up your tiny space.

Comparison Chart: Urine-Diverting Toilets vs. Non-Urine-Diverting Toilets

If you weren’t convinced of the benefits of a urine-diverting toilet already, here’s a chart outlining the key differences between urine-diverting toilets and toilets that don’t separate liquids and solids: 

Pit Toilets and Bucket Toilets vs. Composting Toilets: The Big Difference

A pit toilet is a deep hole in the ground where liquids and solids are deposited together. The same goes for a bucket toilet; it’s just a smaller scale, usually contained in a 5-gallon bucket with a lid. 

While this system can be functional in certain rural or camping settings, it’s not ideal for modern off-grid living in a van or tiny house. Combining urine and humanure in a pit toilet leads to a wet, soupy mess that smells bad, attracts insects, and can even contaminate groundwater if not properly managed.

In contrast, a composting toilet that uses a urine bottle keeps the liquids and solids apart from the start. By separating these elements, you reduce the risk of smells, the need for frequent emptying, and the chance of leaks or overflows. Plus, this system is far more sustainable for the environment, especially for those of us who want to leave a lighter footprint while adventuring in the great outdoors.

Composting Toilets vs. Portable Chemical Toilets

Ok, but what about chemical toilets? Those don’t smell, right? 

While composting toilets rely on natural decomposition to handle waste, portable chemical toilets use powerful chemicals to break down both urine and solids into a liquid slurry. While this might sound convenient at first, there are some serious downsides—both for you and the environment.

Chemical toilets require the use of toxic chemicals, such as formaldehyde, glutaraldehyde, and ammonium compounds, which can be harmful to ecosystems if not properly disposed of. When using a chemical toilet, you're required to empty the waste at designated dump stations where the chemicals can be handled safely. Dumping these chemicals directly into the environment can contaminate soil and water sources, harming wildlife and potentially entering the food chain.

By contrast, composting toilets don’t rely on harmful chemicals. They work with natural processes to break down humanure into compost (with proper handling and time), and the separated urine can often be disposed of directly on the ground, or safely in appropriate locations, such as a greywater system or a public toilet. This makes composting toilets far more eco-friendly, especially when used in delicate environments like national parks or remote wilderness areas.

Plus, with a composting toilet, you’re not lugging around gallons of chemically-laced waste. The solids take longer to fill, and the separated urine bottle, like the one on the Cuddy with its handy 1.7-gallon capacity, is much easier to empty than an entire tank of chemical slurry.

Composting, Pit, Bucket, and Chemical Toilet Comparison

Here’s a high-level comparison of the four types of toilets we’re discussing in this article:

When it comes to portability vs. environmental impact, composting toilets are the clear winner here!

The Benefits of the Cuddy Urine Bottle

Now that we know how important urine diversion and a urine bottle is, let’s talk about why the Cuddy composting toilet is a cut above the rest. Its urine bottle may seem unassuming, but this small container does some heavy lifting.

1. Generous Capacity: The 1.7-gallon capacity ensures that you won’t be emptying the bottle multiple times a day (depending on how many people are using it). For the average user, this means a few days of use between emptying, making it super convenient for long road trips or extended stays in remote areas.
2. Overflow Prevention: The built-in light indicator takes away the guesswork—and the anxiety—around when it’s time to empty the bottle. No more panicking in the middle of the night, wondering if you're about to have a dreaded pee-bottle-overflow situation. The light glows to alert you before things get out of hand, giving you plenty of time to find a safe and appropriate place to empty it.
3. Simple Disposal: Speaking of emptying the bottle, the process is incredibly simple. Just lift the lid and seat, pull out the urine bottle, empty, and replace! You can safely dispose of urine on the ground away from water sources, in a regular toilet, a dedicated greywater system, or even use it as a nitrogen-rich fertilizer for certain plants if you're feeling extra eco-friendly. (Just be sure to dilute it with water to avoid over-fertilizing!)

How to Clean and Prevent Odors in Your Urine Bottle

Even though Cuddy’s urine bottle is designed to minimize odor control, it’s always a good idea to clean it periodically to prevent any lingering smells. If you ever notice a stubborn urine odor coming from the bottle, here are some simple tips to keep it fresh and clean:

• Rinse regularly: After emptying, give the bottle a thorough rinse with water to wash away any remaining residue.
• Use a vinegar solution: If the smell persists, mix one part vinegar with three parts water and let it sit in the bottle for about 15-20 minutes before rinsing it out. The vinegar helps neutralize any lingering odors.
• Add a splash of baking soda: For extra freshness, sprinkle a small amount of baking soda into the bottle after cleaning. Baking soda naturally absorbs odors and can help prevent smells from building up over time.
• To minimize odors: Once cleaned, add an acid to your collection container before adding any urine. This will help reduce odors by stabilizing the nitrogen and preventing the formation of smelly ammonia. We recommend adding ½ - 1 cup of white vinegar or ½ teaspoon of citric acid per 1 gallon of urine. Adding vinegar or citric acid lowers the pH of the urine, which affects the storage sanitization process if you use urine for fertilizer. 

By keeping up with regular maintenance and using these simple tips, your urine bottle will remain odor-free and functional for years to come!

A Urine Bottle is The Unsung Hero of Your Composting Toilet

The urine bottle may not be the star of the show when you think of composting toilets, but it’s the MVP when it comes to functionality and odor control. By separating liquids and solids, composting toilets like the Cuddy remain smell-free, low-maintenance, and environmentally friendly.

With its generous capacity, built-in overflow light, and easy disposal options, the Cuddy urine bottle is designed with convenience and simplicity in mind. Whether you’re vanlifing across the country or setting up your tiny home off the grid, a urine-diverting system is the key to keeping your bathroom clean, odor-free, and eco-friendly—without the harmful chemicals and restrictions of a portable chemical toilet.