Compost Toilets

Compost toilets are one of the systems found on most permaculture projects. They save water and enable us to turn human waste into valuable manure. They are also easily constructed without the need of extensive plumbing for sewage. The general public’s initial thoughts about these toilets are usually that they are smelly and dirty, and sometimes they are, but they really don’t need to be. They can be built into a nice bathroom and kept very clean and without any bad smells. After doing your business, instead of flushing, a large scoop of wood shavings is put into the container to cover everything so that it doesn’t smell. The combination of organic human waste and carbon wood shavings decompose over time into rich manure.

Our home made compost in a provate wooden hut
Our home made compost toilet in a private wooden hut at Keela Yoga Farm

To insure that you don’t spread any pathogens from someone who visits the farm, the ‘humanure’ must be left for over a year to fully, heat up, decompose and kill all the nasties.

At Keela Yoga Farm we will build various type of compost toilets around the land and some of them will be built on our natural building or permaculture in practice courses.

Below are the types of compost toilets that we will experiment with:

Not much more than a hole in the ground – Quickest and easiest

Dig a hole in the ground, put a box on top of it with a hole in it and a toilet seat on top. Do your business and then cover it with sawdust to prevent smell and flies. Continue to do this until it is full and then cover with soil and move to another hole. At each site you can plant a tree such as a willow that thrives on the moisture and nutrient rich environment and cleans it. This method is very temporary and not ideal but can be built in a day. This can be made even cleaner by building a movable shed like structure over the box that could be moved to the next site, it can even tiled inside to make it clean but this makes it heavier and harder to move.

awakened forest project compost toilet
Compost toilets can be built anywhere. Is pone over a hole in the ground at Awakened Forest Project in Portugal

Compost bucket system – Quick and easy

An easy way to build a quick compost toilet that can be kept clean, is by having a small container for storing the waste and sawdust, such as a small bucket or a larger rubbish bin. These can be hidden away in a nice box under a bench or box. The bench has a hole in with a toilet seat on top. Once the bin is full it has to be emptied into a compost pile and the bucket can then be cleaned and put back. This can be built very quickly and kept clean as after emptying the bucket, the whole area can be fully cleaned. The only issue with this method is that you have to empty it regularly. We have had to do this at some places that we have volunteered at around Portugal and it is not too bad. One option is rather than emptying it every time, when one is full you can stick a lid on and fill up another, then you can empty a bunch of them in one go. It takes about one week for two people to fill a large dustbin. To reduce the smell and weight of the bin, it is better to have a separate urinal. The urine can also be stored and kept to use a nitrogen fertilizer for the trees and plants that need more ammounium nitrogen.

Compost toilet over two bins at Tera Alta in Portugal

Single long drop – Harder to build, easier to maintain

We have seen systems where the hole under the toilet seat leads to a large chamber that can take months to fill up. The chamber has another access hatch much lower down and when the chamber is full, the manure near the bottom hatch should have decomposed a little. At this point you empty half of it and add it to a humanure compost pile to leave for a year to fully decompose.  The chamber could be made of anything from wood or concrete to a large plastic container.

An idea solution – Harder to build, less maintenance

In the bathroom there are three toilets: one urinal and two long drop compost toilets. The long drop compost toilets have containers that hold the waste and is several meters deep with an access hatch at the bottom. Each should be built to take around one year to fill up. When one is full you close the hatch and use the second one. When the second one is full you close this off and half empty the first one, this should be mostly decomposed but you can then leave in a compost pile for another year to be sure. I personally like the idea of half emptying it as that will leave a lot of the bacteria, worms and other microorganisms in the long drop that eat the and help to decompose the waste there. This method is more permanent and requires less moving of waste. However, as it’s so big it could be a harbor for rats so it must be built so they can’t access it. I have also seen a similar method where the whole toilet is moved to the secon hole, the means there is no need for an axess hath lower down. However i dont think that will allow enough airflow.

There are many other methods of compost toilets but these are the four we will build to begin with on our permaculture and natural building courses. We will also be building an eco flush toilet system that will combine water harvesting system using vermicomposting, septic tank, reed bed system and grey water system that feeds an orchard. Join our mailing list to recieved our designs for each of these system when we publish them.

Worm Farm
Worm compost farm, worms then can also be used in the humanure compost piles to help speed up the decomposition process

Other ways to improve the compost toilet.

  • Remember that we rely on microorganisms to eat the waste and turn it into soil. If you kill the microorganisms the waste won’t decompose. Most cleaning products available in supermarkets are made of chemicals will kill all the bacteria so you must use natural organic cleaning products to ensure you don’t kill any good bacteria. Better yet, make your own!
  • Tile the bathroom. Many systems we have visited are quickly put together and completely made of wood. Tiling everywhere makes it much easier to clean and makes it look and feel cleaner. This can be done by buying tiles or recycling broken plates and tiles. These can be broken down and then used to make a huge mosaic.
  • A vent. At the top of the container should be a chimney pipe that goes outside at a high height with a small fan blowing air out of the pipe. This will remove air and any odour from the container and create a vacuum in the container. This means when you open the toilet seat, the vacuum in the container will cause air to be sucked into the vessel, meaning no air comes out to the bathroom causing any bad smells.
  • Add microbiology. By breeding the bacteria that eats organic material (which we will be doing to add to our soils anyway), you can add these to the compost toilet to speed up the decomposing process.
  • Add worms. Compost piles naturally attract worms but there is no harm in adding some composting worms, especsially as we all should all have a vermiculture worm farm with excess worms, well eventually anyway. These worms will eat the waste and turn them into worm castings, which is practially soil.
  • A good clean compost pile with storage for hay to cover the pile, water harvesting and cleaning system
This is a mosaic made up of broken plates at Rainbow City Portugal, however this method can be used to tile a bathroom as well

In rural Portugal and all over the world, it wasn’t that long ago when septic tanks or sewage systems where non existent, and these types of compost toilets were everywhere. All of these nutrients were added back into the farm rather than be flushed away. Modern farms are designed to take all of the nutrients away from the farm, by flushing the toilet waste away, selling all the proceeds and clearing the weeds. We will create systems that will make our farm more fertile every year, just like in the wild woodlands or forests. To be sure not to spread any disease we will only use the compost in our reforestation projects and not in any kitchen gardens for fruit and vegetables that will be consumed.

Compost toilets really can built anywhere! here is one with a view at Vale Sarvinda in Portugal

Please do come and visit us to see these systems in action or join our courses to have a go at building them. Otherwise check out the following book; ‘The Humanure Handbook’.