How Does A Composting Toilet Work?

In a traditional household system, blackwater (wastewater from regular upflush toilets) is combined with dirty water from showers, sinks, washing machines. etc. (grey water) and discharged to an on-site septic tank or the sewer. Typically, the end product is disposed of merely as waste, which could potentially degrade the environment.  That’s why composting toilets are increasingly becoming popular among environmentally conscious homeowners looking for a harmless, eco-friendly way to deal with human waste. But how does a composting toilet work?

A composting toilet, also known as a dry toilet or a biological toilet, is an alternative sewage treatment mechanism that breaks down human waste on-site and converts it into a usable material similar to humus. The best composting toilets are usually described as ‘waterless’ because there’s no need to flush the contents. A composting toilet system allows you to dispose of human waste safely without being hooked up to the city sewer or relying on a septic system.


Who Needs A Composting Toilet?

A composting toilet is a practical solution for people living in places where septic systems or city hook-ups are not available or are not a cost-effective solution. A composting toilet could also be a great option for those looking to live off the grid in their tiny homes, RVs, boats, or cabins. Modern composting toilets are highly efficient when it comes to breaking down human waste and leaving your house completely odorless without using water.

Admittedly, it’s a bit confusing trying to wrap one’s head around how a waterless toilet handles and decomposes human feces in a safe, odorless manner. Fortunately, that’s why we wrote this piece. In this article, we take a close look at how composting toilets work to help you get a better understanding of this waterless human waste disposal mechanism. Keep reading to find out why this eco-friendly waste disposal system might be a great option for your home.

How Does A Composting Toilet Work?

Composting toilets convert solid waste into compost by creating an oxygen-rich environment that facilitates the breakdown of the waste pile by aerobic bacteria. While there is a wide variety of composting toilets in the market, they all utilize a similar principle when it comes to decomposing human waste. To understand how a composting toilet works, we must first have a good understanding of the key components of a composting toilet.

A composting toilet is comprised of a sitting part and the collection or composting part. The former only helps you get in a comfortable position to relieve yourself while the latter is where all the magic happens. With composting toilets, you won’t have to worry about local plumbing codes or expertise installation. The collection or composting part plays an important role in the entire decomposition process. This is where human waste is turned into usable soil. The collection/composting part is made up of three major sections. These are:

#1: Storage/Composting Chamber

The storage chamber does exactly what the name suggests. This is where waste is reserved immediately after dropping. It serves as a storage section where all the waste is dropped and reserved for decomposition to take place. It’s also the composting chamber where the natural breakdown of urine and solid waste to a stable organic compound occurs. To make the urine and solid waste separate easily, most manufacturers use a slope shape design.

#2: Aeration/Ventilation Unit

Smelly gases have to go out naturally for a composting toilet to perform at its best. The aeration or ventilation unit is designed to help maintain the level of temperature, ventilation, and oxygen needed to create optimal conditions for the decomposition process. This helps keep the toilet continuously aerobic so that it can release smelly gases in a natural manner and facilitates better decomposition at all times.

#3: Leachate Management Mechanism

Any contaminated liquid that is generated from water seeping through a solid waste disposal site leading to the accumulation of pollutants is known as leachate. Composting toilet systems feature a leachate management mechanism that is designed to facilitate the quick elimination of excess liquids that might end up mixing with the waste. The leachate management mechanism creates the perfect conditions for bacterial activity which, in turn, enhances decomposition.

How Composting Toilets Break Down Waste

Now that we know all the components of a composting toilet, let’s look at how they help in breaking down waste into usable soil. Generally, composting toilets come with chambers to help separate and decompose the waste. Some units may feature just one or two chambers while others come with more – it all depends on the manufacturer. The first step is to separate urine from solid waste. In multi-chamber compost toilet designs, urine is moved to allow evaporation to take place.

The urine moves by gravity to the deepest part of the collection/composting chamber where it’s converted into a nitrogen-rich liquid. The separation of urine from solid waste is an important part of the process as it helps prevent lousy odors. Failing to separate urine from the solid waste makes the process anaerobic, which is where the foul smell comes from.

Composting toilets take advantage of the fact that human waste is 90 percent water, which can evaporate really fast. The mechanisms used to hasten the evaporation of liquid waste varies among manufacturers. Some manufacturers incorporate environmental elements such as sun and wind as catalysts to the evaporation process in their designs. These composting latrines are known as passive composting toilets.

Others are fitted with certain electrical systems that heat the liquid waste and hasten evaporation for faster decomposition. The separation of urine from solid waste enhances the activity of aerobic organisms. These organisms break down the waste, slowly but actively, at the composting chamber. However, it’s essential for the compost to remain a little moist for fast and natural decomposition. Therefore, the compost should never be left completely dry.

Organic Materials

The right amount of carbon materials must be added for faster decomposition. Carbon materials may include elements such as earth, straw, ash, wood chips, and sawdust. When human waste is composted correctly, the end-product does not contain viruses or pathogens. These are eliminated by the bacterial breakdown. The dry compost material is similar to topsoil biologically and in chemical composition.

Dry compost is rich in plant nutrients and is safe to use for gardening and backyard fertilizing. You can use this nutrient-rich fertilizer around the base of trees or plants around your compound as part of the natural cycling of nutrients. By using dry compost as a fertilizer, you will be helping preserve local water quality. You will also be able to reduce the use of commercial fertilizers which can have detrimental effects on the environment.

Balancing the Conditions

Most portable potties for camping or home-based composting toilets turn human waste into fertilizer through the natural process of decomposition. And while it may sound like a simple process, it’s somewhat a complex process. Decomposition takes time and needs a very specific set of environmental conditions to be met for the process to achieve maximum efficiency. In other words, a composting toilet transforms human waste into hummus or humanure through microorganism breakdown under strictly controlled aerobic conditions.

There are four fundamental components that must be present and well balanced for decomposition to occur naturally in a composting toilet. These are moisture, oxygen, aerobic bacteria, and heat. These components must also be well-balanced for a successful bacterial breakdown. That’s the only way that a composting toilet can efficiently:

  • Evaporate liquid waste.
  • Decompose waste fast without releasing a foul smell.
  • Produce a pathogen and virus-free end-product.

Composting toilets take advantage of natural factors that affect decomposition to achieve composting through a carefully engineered process. The mixture of human waste, toilet paper, and other organic material will decompose naturally as long as these elements are in place and in the right proportions. Compost toilet manufacturers have different ways of ensuring that these conditions are met.

How Long Does It Take for The Waste to Decompose?

There’s no doubt that composting toilets work. For most people, the amount of time a composting toilet takes to breakdown human waste into natural fertilizer is an important factor. So, how long does it take for a composting toilet to turn human waste into humanure? Well, that depends. There are several variables that affect the speed at which composting toilet works. These include:

  • Toilet Design. The design of a composting toilet can affect how fast or slow it decomposes waste. Some units are designed to facilitate fast decomposition while others are suited for slow decomposition.
  • Balance of the Elements. The balance of moisture, oxygen, aerobic bacteria, and heat can affect the speed of the decomposition process. The toilet will take longer to fully decompose the waste if the conditions are not met.
  • Capacity. The volume of waste a composting toilet can take affects the duration of the process. When the quantity is manageable, the process will be noticeably faster and vice versa.

A composting toilet, also known as a dry toilet or a biological toilet, is an alternative sewage treatment mechanism that breaks down human waste on-site and converts it into a usable material similar to humus. A composting toilet can be a great option for you if you live in a place where septic systems or city hook-ups are not available or are not cost-effective. Composting toilets don’t use water or dispose of waste as merely waste, which makes them an eco-friendly option.

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