Build Your Own DIY Composting Toilet Cheaply and Easily

The average person throws away 9 times their body weight in waste every year. What is worse, nearly 30% of that waste is food scraps and yard waste that could be used to create compost.

Compost is organic material that you can add to the soil to help plants grow. People have used it alongside manure to enrich the soil with nutrients that plants use, but also to improve moisture retention in regions affected by drought.

It may come surprising that human waste can also be successfully composted by using an easy-to-make composting toilet that everyone can build.

So, let's take a look at how you can build simple DIY composting toilet and take a bold step towards sustainability. 

What Is A Composting Toilet? 

This way, you can safely use composted “humanure” in your garden, even for fruit trees and vegetables. 

Types Of Composting Toilets

Self-Contained 

Central or Remote

How Does A Composting Toilet Work?

A composting toilet works by separating the liquid from solid waste, mixes the solid with sawdust or similar absorbent materials, and then turns it to compost. Whether you choose self-contained or split type DIY compost toilet the other, they both follow a similar concept and consist of these parts:

Now you need to stir the compost up. Turn the spider handle that is attached to the agitator bar to mix the feces with the existing compost and carbon material. If you’re using a DIY toilet with a simple plastic bucket, just throw another layer of sawdust.

Once the toilet is full, remove the urine container and empty it in a safe manner. For the composted part, you need to follow your state or local guidelines to dispose of compost. The best place to start is your state’s department of health website.

If there is any leftover compost matter clinging to the sides of the composting chamber, rinse the container using a garden hose with a high-pressure attachment. After you’ve cleaned it, tip the water onto your outdoor compost heap. Dry the bucket with a rag and spray the interior with vinegar.

Remember not to use chemical cleaners as their residue may kill the good bacteria that break down the waste into compost.

How To Build A DIY Composting Toilet

You'll be able find many composting toilets DIY plans online, but if you want to build the simplest and the most effective variant with a plywood frame and a 5-gallon bucket, you're going to need:

Materials

Tools

Steps

Step 1. Build The Box

Your DIY composting toilet needs to be comfortable as this is where you’ll be releasing your humanure day after days. If it’s comfortable, it will make the experience more enjoyable. When it comes to toilet comfort there are two key things:

Height — Naturally the taller the toilet, the easier for you to sit and stand up. However, the doctors say that the more you squat, the better you may empty your bowels. Find the ideal height by trying to sit and stand from objects of different height to get the ideal measure.

Toilet seat — This is entirely up to you, just make sure it’s durable and comfortable.

To build the frame of your composting toilet, you need to decide on the dimensions, by considering the available space. Remember that it needs to include the size of the toilet seat.

Cut out six pieces of plywood for the top, bottom, and four sides of the box. Attach the pieces together using a pocket hole jig to make the box stronger and to hide all those screws from plain sight.

Step 2. Cut The Hole

You need to keep the top section of your plywood box loose so you can access the bucket. On the other hand, you’ll need to cut a hole in the center for the waste to fall inside. You can use the toilet seat as a template:

1. Place it on top of the plywood
2. Open the seat lid
3. Take a pencil and draw around the entire inside circumference

You can freely cut the circle a bit wider to give yourself more wiggle room. Start cutting by drilling a hole somewhere on the line so you can insert the jigsaw blade. Unless you’re a seasoned DIY carpenter, your hole is not going to be perfect, so use a file to soften the rough edges and finish them with sandpaper.

Once the box is done you may choose to stain or paint it to give it more character.

Step 3. Add The Urine Separator

Attached to the top, the urine separator channels the urine into a separate container in your DIY composting toilet. This helps compost toilets neutralize the smell, but also makes it easier to dispose of urine and keep the solid waste bucked drier.

Screw the urine separator to the underside of the plywood lid, at the front.

A composting toilet is not an outhouse, latrine, privy, or anything like that. If you build it right, it gives off no foul odor.

Step 4. Install The Toilet Seat

Place the toilet seat assembly on top of the hole you’ve just cut. Mark the drill holes with a pencil. Use a strong screwdriver to drill small holes for the toilet seat hardware, making sure the holes are tight enough so the screws don’t get loose with use.

Step 5. Give It Legs

While the whole plywood box can rest on the floor by itself, it’s always better to give it legs. Bathrooms are wet places, and sooner or later there’s going to be water on the floor, and plywood and water don’t play nice.

Place each 2x4 wood at the four corners of the plywood box and screw together. Place the whole thing on the floor to see if it stands firmly. If any of the legs are shaking, check the screw to find any additional spacings.

Step 6. Get The Buckets

To complete your composting toilet DIY project you need to find buckets of the right size. One for number 1s and the other for number 2s.

An ideal container for urine is long and narrow. If you have trouble finding something like that, a 3.5-liter plastic pot would be enough for a day.

As for the solid waste bucket, you can use 5-gallon (about 20 liters) plastic buckets. Be sure you have at least three buckets in rotation — two can be full at all times and one being used.

Step 7. Add Absorbents Into The Bucket

For the last step, add a few inches of absorbent materials into the bucket. You may use dried leaves, wood ash, or sawdust (hardwood sawdust is the best). The sawdust soaks up the excess moisture but also neutralizes the bad odors.

Here's a video that shows all the steps I've outlined above. Now the steps here may be in a different order, but they all add up to a similar final result. Check it out below.

Reasons For Building A Composting Toilet

Greener Alternative To Septic

Septic tanks are expensive, and in certain layout and land conditions, the use of a septic tank would not be possible at all. Not to mention environmental regulations that may prohibit the use of septic tanks where you live. A DIY composting toilet, on the other hand, lets you deal with your stuff on your property in the greenest possible way — by turning it into food for plants.

Conserves Water

Even in this time and age, there are regions that struggle with water scarcity, and not all of them are in developing countries. When compared to traditional toilets that waste up to 5 gallons of water on a single flush, for a DIY composting toilet described here, you need very little to no water. 

No Plumbing Required

If you’re looking into compost toilet DIY tutorials, chances are that you plan to use one where plumbing is not available, such as an outdoor cabin. A composting toilet is also a great option for an old building, where plumbing is either inefficient or non-existing. From an environmental point of view, having a composting unit makes much less impact than you having to tear out the old and running new pipes through the building.

Inexpensive

While you can go and buy a ready-made composting toilet, this is all about being self-sustainable and making do with materials you have at hand, with minimum waste. The 5-gallon bucket version with a plywood frame and urine separator will set you back about $10. You won’t be creating any waste and won’t have to pay for someone to install it.

Odorless Option

When compared to an outhouse, a DIY composting toilet has a significant advantage — you don’t have to deal with foul odors in your property. Helped with the carbon material, the whole composting process is carried out by bacteria under aerobic conditions. The final product is eco-friendly odorless compost which you can use in your garden.

FAQ

Conclusion

A DIY composting toilet is a great alternative to a chemical toilet or outhouse. It’s odorless, eco-friendly, and can fit almost anywhere you need a restroom.

Above all, these toilets are among the most sustainable options today. They need very little or no water, so they are great if you want to minimize your water consumption. They produce no pollution, as there’s no septic tank that you need to empty, and you don’t add to municipal sewage.

This type of toilet is also easy to build: if you can handle standard house tools, then you should start building a functional composting toilet today.