Does Cuddy Composting Toilet Smell?

Does Cuddy Composting Toilet Smell?

Composting toilets like Cuddy are becoming increasingly popular with van-lifers and RV owners as a sustainable and eco-friendly alternative to traditional flush toilets. However, one of the most common questions we get is: does Cuddy the composting toilet smell? Short answer: no! Long answer: still no, but let’s explore the various reasons and factors that can contribute to a compost toilet smell and discuss ways to mitigate any potential odor issues with portable toilets, including Cuddy.



TL;DR summary

No, your portable Cuddy composting toilet should not smell of waste. That’s because of our unique design, which includes the addition of a carbon filter and ventilation fan. However, if you do catch a whiff of something unpleasant, we have a troubleshooting guide below.



Why do people think composting toilets smell?

When someone hears “composting toilet,” they may start recalling a traumatic experience in an outhouse-style toilet. You know, one of those bottomless pits that you fear falling into (or fearing for your phone’s life should it fall out of your pocket into the deep, dark abyss). Relax – everything’s going to be okay; composting toilets are NOT outhouses, nor do they smell anything like a derelict port-a-potty. Before we begin talking about a composting toilet’s smell, odor, and the like, we might need to first define what a composting toilet is.


What are composting toilets?

Composting toilets like Cuddy are compact and portable waterless toilet system that uses the natural processes of decomposition to turn human waste into compost. The composting process takes place within a specially designed container or chamber where the waste is broken down by bacteria and other microorganisms. We may be a bit partial, but the best composting toilets are UDDTs (urine-diverting dry toilets) because they separate liquids from solids, which is what Cuddy is and does so well!

One of the key advantages of portable composting toilets is their versatility. Cuddy and his kin can be used in a variety of settings, from conversion vans to remote cabins and off-grid tiny homes. The self-contained nature of a portable composting toilet makes it ideal for locations where access to water and sewage infrastructure is limited or nonexistent, and best of all, composting toilets do not stink like an outhouse, either!


How does a composting toilet work?

Toilets that compost work by converting human waste into compost. They also help reduce the strain on sewage systems and minimize water usage.

The best portable composting toilets that do not smell are UDDTs because they separate liquid waste from solid waste. The solid waste is mixed with organic materials such as coconut coir or sawdust to aid decomposition and control moisture levels. Cuddy has a patented agitator handle and internal mixer in order to easily stir the contents and expedite the composting process. The mixture is stored in its solids bin, where aerobic bacteria break down the waste through biological processes.

It’s important to remember that portable composting toilets start the comosting process, however this process needs time (6-12 months) and heat to complete and be pathogen free. At the point of decomposition, you get “humanure” a nutrient-rich compost that can be safely used in gardening, landscaping, and agriculture.

So why do we want to separate urine from the soild waste? Here’s the science bit!



The science behind the smell in composting toilets

While Cuddy the composting toilet is designed to be odor-free, it is important to understand the role of bacteria in the decomposition process and how certain factors can affect the smell that may be emitted from portable toilets.



Why do toilets smell?

All toilets – including compost toilets and your typical flush toilets – can smell for a variety of reasons, including residual waste on the toilet bowl to sewer gas backing up from standard plumbing pipes. The terribly unpleasant smell in outhouses and port-a-potties is due to liquid waste mixing with solid waste; the high ammonia in human urine kills the helpful microbes and bacteria found in solid waste, causing it to sit there and stink for an eternity since it cannot be broken down naturally – nor odor-free.

Thankfully, composting toilets that are UDDTs like Cuddy separate liquids from solids, eliminating the dreaded sewage smell while kickstarting the natural decomposition process, further removing the chance of your composting toilet smelling.



The role of bacteria in composting toilets

Bacteria are crucial in breaking down waste and reducing odor in composting toilets. Aerobic bacteria thrive in an oxygen-rich environment and convert organic matter into CO2 and water. These bacteria are responsible for the decomposition process that transforms waste into compost. However, improper maintenance or lack of oxygen can lead to the growth of anaerobic bacteria, which produce foul-smelling gases.

Luckily for you, Cuddy was designed to perfectly manage temperature and humidity levels within the composting toilet itself, and, with the help of Cuddy’s internal agitator, mixing up the organic content aerates the environment further, leading to very happy, healthy, and odor-free bacteria—and a smell-free bathroom!

If you have a composting toilet and are experiencing a bit of a whiff, then the next bit is for you.


Why does my composting toilet smell?

Several factors can influence why your composting toilet might smell. Understanding these factors and implementing appropriate maintenance practices can greatly reduce any potential odor issues with your composting toilet or other portable camping toilets. Cuddy actually has some smart (and smell-free) solutions built into it to help mitigate odors right from the get-go!


Is your composting toilet a UDDT?

As we mentioned, a UDDT (urine-diverting dry toilet) is a type of composting toilet that separates liquids from solid waste. This is crucial for minimizing the unpleasant sewage smell that happens when urine is mixed with human waste. If you have a portable toilet that does not have a urine diverter, where all waste is stored together, then your composting toilet smell is going to be very unpleasant. Here’s a YouTube video we made about UDDTs vs standard composting toilets.


Maintenance and cleaning practices

Regular maintenance and cleaning are essential for odor control in composting toilets. This includes emptying the solids bin when it is full, inspecting and replacing any ventilation components, and ensuring proper airflow within the system. Additionally, keeping the toilet clean and free of debris or excess moisture is always good practice. Sometimes spraying the bowl with diluted vinegar can help eliminate any smells, and also adding a scoop of Diatomaceous Earth to the solids bin after heavy use can help keep things odor-free.


Usage frequency

The frequency of use will impact the smell of every toilet everywhere. A higher frequency of use results in more waste being introduced into the solids bin, which may increase the potential for odor. Proper management and replacement of organic material can help mitigate the smell associated with frequent use; our favorite is coco coir, although others praise peat moss and sawdust.


Cuddy’s carbon filter and fan

Besides separating liquids from solids, the main reason why Cuddy does not smell is thanks to its internal carbon filter and ventilation fan! Our composting toilet features a fan that draws air through an activated carbon filter to prevent odors escaping.

Cuddy does not need to be vented externally, however, if you choose to do so, setup is easy! Here’s how to externally vent your Cuddy Composting Toilet.

Once you’ve established why your portable toilet is smelling, it’s time to do something about it. Here are our top tips.


How do I stop my composting toilet from smelling? (Our 3 step checklist)

If odor issues arise (literally) with a composting toilet, there are several things you can do to minimize or eliminate any unpleasant smells.


1. Make sure you have proper ventilation

Adequate ventilation is crucial for odor control in composting toilets. Proper ventilation allows for the continuous flow of fresh air within the composting chamber (and your bathroom), reducing the chances of anaerobic bacteria growth and foul odors. Installing a ventilation fan or using ventilation methods such as air vents or chimneys can greatly improve air circulation and minimize odors.


2. Add carbon additives

Adding carbon-rich materials, such as sawdust, dry leaves, or coconut coir, to the composting chamber can help absorb moisture and neutralize odors. These carbon additives provide a food source for the aerobic bacteria responsible for the decomposition process, promoting their growth and ensuring efficient waste breakdown.


3. Make sure you don’t add toilet paper or feminine products

We can’t speak for other composting toilets, but it is not recommended that you place toilet paper inside of Cuddy. Why? Even though it is true that toilet paper is biodegradable, toilet paper can easily get wrapped around Cuddy’s internal agitator, which can slow the decomposition process while also quickly filling up the volume of the solids bin. It is best to place used toilet paper and feminine products in a separate receptacle so that you are not forced to empty the solids bin so frequently. Speaking of which…


How often do I empty a composting toilet?

The frequency of emptying a composting toilet depends on various factors, including the size and setup of the compost toilet, the number of people using it, and the capacity of the chamber(s). On average, most couples using Cuddy empty the liquids bottle once or twice a week, whereas the solids bin only needs to be emptied about once a month! Cuddy has a smart LED light for the liquids bottle to indicate when it is time to empty, ensuring that there’s never an “oops!” moment. Finally, the solids bin in Cuddy should be emptied whenever it gets too challenging to easily turn the agitator handle.

Of course, it’s important to adapt to your situation, monitor your toilet's fill levels, and follow any manufacturer's guidelines to ensure efficient decomposition and prevent overloading the system (or your space). If you would like more information on how to keep your composting toilet smell-free, read our helpful guide on keeping your Cuddy happy here!


Sweet, sweet victory: Cuddy the composting toilet does not smell!

Toilets that compost do not smell if properly maintained. And with Cuddy, unpleasant odors are whisked away through the fan and carbon filter. Should any odors arise from any composting toilet, you now know how to mitigate them through regular maintenance and effective odor control strategies. By following the best practices and understanding how these portable toilets work on a biological level, composting toilets can provide a sustainable, eco-friendly, and odor-free alternative for waste management no matter where you are in the world!

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Richard Peter

Richard is the Co-Founder and CEO of Compocloset, and the mastermind behind the Cuddy Composting toilet.


After a career algorithmic trading, he had plans to follow his long held passion for AI but the pandemic brought about an unexpected twist.


After installing a composting toilet in his campervan he caught the sanitation bug (not the dysentry kind) and saw an opportunity to change the world for the better and help bring safe sanitation to the 2.6 Billion without it. 


He's now on a mission to make the best off-grid toilet possible both for you and the planet! 


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