How to Build a Worm Composting Toilet?

If you’re interested in building a composting toilet, you should know how to build a worm composting toilet. These toilets provide a precious resource in humanure and are workable with a traditional flush toilet. If built correctly, you can use your homemade composting toilet for years.

A compost toilet can be as straightforward as using a bucket. Still, a bucket system means you’ll have another chore every week, emptying and managing the buckets. That starts to get annoying fast, especially if you have a lot of people using the toilet. Hence, many go with a worm composting toilet, which you can build over a divided concrete vault.

There are various methods to build any compost toilet, especially since the off-grid community is very supportive and interested in home projects. If you feel there’s a better method or solution after reading our recommendations, leave a comment below! Nothing’s better than getting a conversation going with this sort of thing.

Nevertheless, this guide will cover the basics and necessary information related to worm composting toilets. We’ll discuss what a composting toilet is, what a worm variation is, how to build one, and how composting works. By the end, you’ll have a better idea about worm composting toilets and where to begin.

What’s a Composting Toilet?

A composting toilet is similar to what we know as a toilet, but instead of flushing away waste, it turns it into compost. Many people use composting toilets to turn something we usually throw into a resource. It’s not an outhouse or outdoor hole but acts and looks similar to a traditional toilet.

The most significant advantage of a composting toilet is that most don’t require plumbing (though the vermicomposting toilet we’re discussing does). This means that you can build a composting toilet pretty much anywhere. The toilets operate from absorbents (sawdust, pea moss, etc.), creating a natural process that breaks down your waste. From an environmental standpoint and versatility, it’s a no-brainer to utilize a composting toilet.

What is a Worm Composting Toilet?

Also known as vermicomposting toilets, worm composting toilets are composting toilets that utilize earthworms to process waste, urine, and toilet paper. Most systems rely on a conventional flush system, and like standard composting toilets, you deal with the waste on-site.

Worms have been a part of the natural composting process for thousands of years. It wasn’t until the 1990s that people began experimenting with worms for these types of toilets. It helps speed the process up and can benefit your composting toilet unit. Though it may take more time to build than other toilets, it’s very satisfying when done correctly.

Knowing How to Build a Worm Composting Toilet

A worm composting toilet works similarly to a traditional composting toilet, but there’s the added element of worms in the compost pile. The worm addition allows for a further compost process between organisms, bacteria, fungi, and more. All of these work together to break down the waste in your system.

As you can expect, there are additional steps you’ll need to take to ensure your worm composting toilet works properly. Also, not all composting toilets can work with added worms. For example, it won’t work if your composting toilet has a mixing functionality. Worm composting toilets work well in a split system, so the worms live in a separate container system where they’re not agitated or moved by mechanical means.

If you already have a self-contained composting toilet, adding redworms can help speed up the process. That’s all you need to do. This method is only recommended if you’re looking for a lengthier project to turn your flush toilet into a vermicomposting flush toilet.

Design and Construction

The design we’re recommending for this worm composting toilet system is one you can add to your already existing toilet. It doesn’t require external energy or a separate machine to process the sewage. There are two primary parts, an insulated tank that keeps the worms in their ecosystem and a green filter area that allows the water to be cleaned further. The water is then returned to the environment.

Siting the Toilet System

This toilet system operates around the processing of sewage, which applies to the worm tank and the green filter section of the system. The green filter section needs to be kept within 0.5m of soil since that’s where worms thrive. Usually, the siting of the green filter area determines where the system lays.

The system is gravity-fed, meaning it works best on sloped sites or an area where the toilet’s waste pipe outlet is half the tank’s height. Placing the tank in your basement is possible since the system has no odor issues when it’s working correctly.

If you live in a flatter earlier, the tank can be sunk 0.5m into the ground without ruining the system. However, any more and the tank drainage will start to get too deep into the soil. Also, don’t forget to allow a minimum drain slope between the tank and the green filter.

Burying the Worm Tank?

Although it’s possible, burying the worm tank isn’t ideal since IBC tanks aren’t meant to be buried. You’d need a solid container structure to go around it if you want to go that route. Remember, a buried tank can create problems with drainage unless the water can be piped away.

If you have a drop in the system, it’s easier to install a vessel for the sewage. You can pump it into the worm tank rather than having the tank buried entirely. Doing this would help macerate the solids and make it easier to pump them. Regardless, any option is usually preferable over burning the worm tank.

Understanding the Worm Tank

You can easily make the worm tank from a 1m3 IBC (Intermediate Bulk Container) or pallet tank. These tanks are ideal because of their easy access at the top and their drain outlet at the base. The tanks are sourced in most nations since they’re usually used for bulk transport. You can find one online for a couple of hundred dollars or so.


Access is vital with the worm tank, so you’ll need to cut an access hatch at the top. It will allow you to inspect and add material quickly when the system needs it. Remember not to make the hatch too small since easy access is imperative for loading.

It’s also worth stating that if you have an issue with the tank, having the hatch large enough means you won’t have to get into it to fix it. Remember your toilet’s pipework has to be fixed into the primary access hole at the top of the unit. Don’t cut the top of the tank off. Also, don’t worry about additional ventilation; the tank’s build should cover that.

Insulated Container

Worms survive within a temperature range of 41 to 84 degrees Fahrenheit, but their optimal temp range is 68 to 77 degrees Fahrenheit. If you live somewhere with decent weather, you won’t have much to worry about, but understand that excessive cold or heat will kill them instantly. Keep the worms as close to their preferred temperature range as you can.

The tank will need an encasement in an insulated home in most cases. You can make the housing from brick, blockwork, stone, or wood. No matter the option, it’ll need a hinged roof for access and insulation. Worms also prefer the dark, so be aware of any lightproof required for the tank.


After you have the worm tank set up, you can run the pipework to the tank with the typical size for the toilet waste pipe where you live. Ensure you follow drain slope guidelines to prevent clogs. Any issues will cause major annoyance and potentially ruin the entire project.

If you don’t have plumbing experience, don’t worry. Working with a plumber or following online guides should work since you just have to plumb the pipework through the access hole in the tank. This process will ensure an even distribution of waste and allow the worms to stay insulated.

Tank Drainage

Assembling the system will vary depending on the PVC pipe available where you live. It’s ideal for constructing a wide-diameter perforated pipe less than the tank’s height. As long as it’s higher than the depth of the organic layer, you can fit it into the tank’s exit tap housing.

After the perforations are drilled into the assembly, you can cover it with a nylon mesh. Doing so prevents material and worms from passing through. Don’t use metal, whatever you do, since that’ll cause it to rust. Once the drainage is assembled, you can get it ready to fit into the tank.

After the assembly is placed, the tank can be filled. Begin the process by coursing a gravel layer by the exit pipe section of the tank. Cover it with the nylon mesh layer (as you did earlier). Now, you can add the organic material and cover it with the mesh.

Starting the Ecosystem

Once you have everything connected, you can begin the ecosystem! Begin by filling the tank 75%, complete with coarse organic material. You can use a mix of woody materials (though you avoid sawdust), but no matter what you use, ensure they’re mixed well. The goal is to have a range of materials that decompose slowly.

After the material is added, cover it with a layer of partial compost (animal manure or kitchen scraps). Once you have those two parts covered, you can get the tank ready for worms. Initial compost is good since it’ll contain many of the organisms your system will require.

Adding Worms

What would be the point of knowing how to build a worm composting toilet without talking about worms? Worms are easily sourced from any manure pile since it’s where they naturally congregate. You can also buy them online if that’s easier. The recommended species for this sort of thing is Eisenia Fetida, also known as the redworm.

Green Filter

The green filter beds are fed from the toilet and are filled with the same material used in the worm tank. The process is simple: worm eggs will pass out of the tank into the vermi-water and colonize the green filter areas. Also, the organic material will act like a sponge to hold water for the area.

The recommended soil depth for this system is a minimum depth of 0.5m (not to be confused with a septic tank depth). It works best in a rectangular shape with pipes leading to it (we’ll discuss pipework shortly). It’s worth doing a soil percolation test before proceeding ahead.

Last Pipework

Last up, you’ll have to run the pipework. The pipes should run from the worm tank to a distribution box in the green filter areas. It must be the same diameter or more significant than the tank drain tap. From the distribution box, you can run the smaller diameter perforated pipe through the upper section of the organic material. Remember, green filter sections usually work best to irrigate trees and shrubs.

What to Know About Composting Toilets

As dense as the composting toilet is above, there are plenty of more straightforward, inexpensive options to consider. Much revolves around build type, budget, requirements, and uses. To create a composting toilet, you don’t have to build a sizeable vermicomposting toilet. Some people create a composting toilet for just $20.

Build Type

The two main composting toilet types are a self-contained composting toilet and a central or remote composting toilet (like the one we discussed in this guide). A self-contained composting toilet is when the compost system is enclosed in the toilet and is usually under the bowl.

On the contrary, a remote composting toilet takes the waste to a separate unit that’s not under the bowl. Usually, this location is in the basement or outside. If you have a more extensive remote system, you can have a few of these in your home, similar to a traditional toilet.


The budget for a composting toilet varies greatly. The one we discussed earlier is more time-consuming than anything else but will cost you a few hundred dollars. Some commercial composting toilets are thousands of dollars, while DIY options can cost you as little as $20.

Like anything else, the budget depends on what you hope to accomplish. This vermicomposting toilet solution is ideal if you have a flush toilet that you’d like to turn into a composting toilet. A self-contained composting toilet is a way to go if you need an option for your RV or mobile setting.


Most people use a composting toilet to have a better impact on the planet. Being environmentally conscious is growing in popularity, and many turn to a worm composting toilet. Although a worm composting toilet (that comes from a modified flush toilet) isn’t as versatile as other composting toilets, it has a tremendous environmental impact.

Benefits of Using One

There are many benefits to using a composting toilet. The most significant advantage comes from saving water, not relying on traditional plumbing, and creating compost for plants. It allows you to turn something you usually wouldn’t think or care about into a valuable resource.

  • Environment Impact
  • Saves Money
  • Versatile
  • No Water Requirement (Usually)
  • Reduces Dependence on Traditional Plumbing
  • Reduces Wastewater
  • Creates Compost for Plants


Are Worms Required for Composting Toilets?

No, worms aren’t required for composting toilets. Though there are plenty of examples of people adding worms to their composting toilet, it’s not required. All you need is an absorbent for your waste to allow the decomposition process. Absorbents include coconut coir, hemp stalks, peat moss, wood shavings, sawdust, or chopped straw.

Will Worms Harm Me While Using a Composting Toilet?

No, the worms won’t be in the toilet while you’re using the bathroom. Even if you have worms in your DIY composting toilet, the containers that hold the waste is separate from where you’re sitting. You won’t have to worry about worms crawling around unless you have a design issue. Most of these worms sit still and don’t move much anyway.

Are Composting Toilets Expensive?

As mentioned earlier, some composting toilets are expensive, while others aren’t. Of course, building it yourself will always be cheaper. Still, there are plenty of commercial composting toilets that are very affordable. Also, understand that just because something is expensive doesn’t mean it’s worth it. Always look at reviews and recommendations before making a decision.

Final Thoughts

A worm composting toilet benefits those looking to take the added step with their off-the-grid lifestyle. It might take you some time to execute, but once you do, you’ll be glad you did. Everyone designs their worm composting toilet slightly differently from one another, so definitely keep looking at guides and videos to keep learning.

As great as knowing how to build a worm composting toilet is, none of it matters if you don’t try it. As lengthy as the process may seem, you’ll most likely enjoy and have great satisfaction once it’s built. Don’t just take our word for it! Leave a comment below and get a discussion started!