Condensation in your compost toilet? Here's how to solve it.

Condensation in your compost toilet? Here's how to solve it.

Are you noticing a build-up of condensation in your compost toilet? Questioning where it’s coming from? That is a perfectly normal reaction. In this guide, we’ll take you through the possible reasons for a moisture build-up in your portable loo and how to tackle it.


TL;DR condensation in your compost toilet summary

Essentially, condensation in your compost toilet is not a bad thing. The composting process creates a lot of heat. Excess condensation can be commonly caused by temperature or environmental changes that unbalance what’s happening in the decomposition process. There are ways to solve that, which we go into much more detail below, including adding more ventilation, dry carbon materials and turning your composting pile.

Is condensation in composting toilets a bad thing?

Absolutely not! Condensation is actually a good sign because it shows that the composting process is working effectively. Condensation in our portable composting toilet Cuddy is a common occurrence because the composting process generates heat, which can cause the inside of the toilet to become humid. To prevent condensation, you can try various ventellation techniques or place absorbent materials inside the solids bin to help deal with excess moisture.


Why is there condensation on my compost toilet?

Condensation in your compost toilet can be attributed to a combination of factors, with temperature and humidity being the primary culprits. A little condensation is no cause for concern since the natural decomposition process generates heat and, therefore, can cause moisture to build up.

However, there may be a few reasons for moisture build-up to become excessive.


Temperature fluctuations cause excess condensation

Condensation occurs when warm, moist air from inside the toilet (from the decomposition process) comes into contact with a cooler surface – typically the toilet lid. As a result, the moisture in the air condenses on the lid's surface. This temperature difference can be a result of changes in environmental conditions as well, making condensation a year-round concern in certain environments.


Humidity levels can affect condensation inside the container

Bathrooms are typically humid areas to begin with. High humidity levels in the restroom or the surrounding environment can contribute significantly to condensation inside the toilet container.

If you have a portable composting toilet, like the Cuddy, then wherever you are, road or sea, you will likely experience environmental humidity changes throughout your journey. You may need to account for that. Before we get to the “how to deal with it”, let’s look at what happens when your compost becomes too wet.


What happens if your compost is too wet?

While it is true that the natural composting process relies on a certain level of moisture, excess wetness in your compost can lead to a range of problems. This can slow the performance of your composting toilet, leading to unpleasant smells, mold, and poor-quality compost.

Here is what may happen if your compost is too wet:


Foul odors and compost smell

Excess moisture can lead to unpleasant odors inside and around your toilet due to an imbalance of good aerobic bacteria to foul-smelling anaerobic bacteria. These odors can be a nuisance, especially in small spaces like conversion vans, RVs, boats, and tiny homes. Here’s our full guide to the cause of those nuisance smells.


Inefficient decomposition of compost

A composting chamber that is too humid and wet can slow the decomposition process. This means human waste may not break down as efficiently as it should, potentially leading to emptying the chamber more frequently. Additionally, this will cause longer wait times if you wish to use the compost as human manure. Interested in learning more about humanure? We highly recommend the Humanure Handbook!


Compost mold growth

Excessive moisture anywhere is a prime environment for mold growth. Not only can mold affect the performance of your compost toilet, but it can also, if left unchecked, pose health concerns for the occupants of your living space. Mold is not common, but it should be noted for those with sensitivities to mold allergens.

We should also make a note here - good bacteria in your compost is essential. The difference between the two is the look. Good bacteria look like streaks or patches of white mold running through your compost and on your solid waste. Harmful mold usually forms in patches around the toilet edges and darkens in colour over time.


Solutions for dealing with condensation in composting toilets

Now that you have a thorough understanding of the causes and consequences of condensation in composting toilets, let's explore a range of effective solutions to address this issue. Don’t worry; it’s much easier to deal with than you think.


1. Make sure you have proper ventilation

Ventilation is a critical component of managing condensation in your compost toilet. By ensuring proper airflow, you can maintain consistent temperature and humidity levels. Consider the following ventilation options for your composting toilet set-up.


  • Exhaust fans - Installing exhaust fans in your bathroom or toilet space can help circulate air, reducing humidity and preventing condensation.
  • Windows - If possible, open windows to let in fresh air. This is especially effective in RVs, tiny homes, boats, and cabins where natural ventilation is a viable option.
  • Roof vents - Roof vents or attic fans can help expel warm, moist air from your living space, minimizing the chances of condensation.
  • Internal fan - We designed Cuddy to be the best composting toilet on the market – so we built a fan inside the toilet itself. The internal fan not only helps control moisture and humidity levels inside the toilet, but it also whisks away any unpleasant odors that might be lingering.


Here’s an easy guide on YouTube on how to vent Cuddy externally to ensure even more ventilation.


2. Keep an eye on your compost moisture

Regularly checking the moisture levels in your compost is essential to prevent excess condensation and maintain the efficiency of your composting toilet. If your compost is too wet, take the following steps to rectify the issue:


  • Line it with towels - Before adding anything into the solids bin, line the container with towels. This will help control wetness and humidity.
  • Add dry materials - Incorporate dry materials like sawdust, peat moss, or coconut coir into your compost. These materials absorb excess moisture, balancing the ideal humidity ratio.
  • Turn and mix - Regularly turning and mixing the compost helps distribute moisture evenly, preventing localized wet spots that can lead to condensation. This is why we built an agitator inside Cuddy’s solids bin for easy mixing management!

3. You may need to invest in a dehumidifier

In high-humidity environments, using a dehumidifier in the bathroom can be an effective solution to reduce overall moisture levels. Dehumidifiers remove excess moisture from the air, creating a more comfortable environment and preventing condensation from forming. However, dehumidifiers do require a lot of energy to run, so depending on your situation or set-up, this might not be doable for you.


Compost toilet condensation in winter and summer

To manage condensation effectively in the winter and summer months, you may need to make seasonal adjustments based on the unique challenges of different weather conditions. Here's how to address condensation in both winter and summer.

  • Winter - In colder weather, focus on preventing cold surfaces within the composting toilet. Insulate the chamber by skirting the base and maintaining a comfortable indoor temperature to reduce condensation.
  • Summer - During the summer months, emphasize airflow to reduce both heat and moisture. Proper ventilation, fans, and open windows can help maintain a cooler, drier environment.

So there you have it, condensation in your compost toilet solved!

Condensation in your compost toilet is not a problem or concern when managed effectively. Proper ventilation, insulation, and moisture control are key to ensuring your composting toilet remains efficient, odor-free, and problem-free.

Whether you're using a composting toilet in a van, RV, sailboat, tiny home, or off-grid set-up, these tips will help you enjoy a sustainable sanitation solution in all seasons.

Remember, a well-maintained composting toilet contributes to a more sustainable and off-grid lifestyle, making it an excellent choice for those seeking eco-friendly alternatives for waste management.

Click here to learn more about the best portable composting toilet, Cuddy!


Leave a comment

Please note, comments must be approved before they are published

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! 


Follow along for the latest news! 


Linkedin | TikTok | IG