Treebog Composting Toilet

  

Kendra White

         

                    Composting toilets present humans with a great opportunity to create a closed loop cycle, to return nutrients to the earth, reduce the amount of resources used and to minimize the waste they produce. Fitting a home with a waterless toilet not only shrinks your carbon footprint but it produces highly fertile soil amendments that can be added to the soil for non-edible plants, fruit trees and shrubs. There are many options when choosing the system that best your lifestyle, by considering all of one's needs it's easy to find the most compatible system for your household. Some models can be simple as squatting over a 5 gallon bucket, while others can get complex and include urine diverters, on site composting piles, mobile structures and manufactured, code compliant units which can be installed in one's house. This paper will focus on a permaculture design known as a "treebog," it is a relatively new design which requires very little maintenance and is perfect for the site we are working with.

     Tree bogs were designed by a permaculturist after he noticed how his willows thrived in the area he had been chucking the contents of his compost bucket, he coined the term in 1995. Tree bogs have been gaining in popularity ever since and with such a simple, effective method of cycling its no wonder why they are being utilized more and more. Officially, a "tree bog is simply a controlled compost heap whose function has been enhanced by conscious management and the judicious use of moisture/nutrient-hungry trees" (permaculture-wikia.com/wiki/tree_bog) The design concept for a tree bog is to build a basic compost structure with the commode seat being at least 3ft from the enclosed pile below. All a tree bog really needs is a toilet seat, 3ft between it and the ground, an enclosed area for the waste and then a ring of heavy feeding plants (willows are most commonly used) around the structure, everything else can be as simple or creative as the designer would like. Some important aspects to the tree bog are adequate ventilation, protection from critters and hungry plants to devour the waste. The way it works is that once the waste is deposited into the enclosed pile gravity will help the solids and liquids seep down and the roots from surrounding hungry plants will absorb the waste and immediately convert it to nutrients, if the rate of usage is balanced with nutrient consumption then you should never really have to mess with it again, if however, you fill the enclosure then you simply move the structure to another area close to the hungry plants and start again. The design for the enclosure consists of straw sandwiched between chicken wire, this wicks excess moisture, protects the pile from pesky critters, hides the waste from human view and the ring of hungry plants surrounding the structure slowly help it decrease in size. The enclosure as well as the structure should be airy, you should avoid packing the straw too tight or making everything flush as this will compromise the decomposition process and create odor, with enough air flow the tree bog should have no displeasing smells and very little maintenance. 

  I am working on a site owned by my friend in Calaveras County, her plot is very hilly, wildlife is very present and she has a big range of guests so her usage would vary greatly. It was difficult finding a solution for her property due to space limitations, she lives on 10+ acres but most of it is on an incline so open space is limited, she wanted it away from the ho not impeding the huge hilltop view they have from the deck, and because the number of guests she has at one time fluctuates. I knew it could not be anything that required a ton of maintenance, took up too much room or required storage. I think the tree bog would be the best solution for her toilet problem because it can withstand fluctuating usage, would last her several years to indefinitely, would be easy to design for her property and it would be extremely easy for her to maintain. We could utilize one of her hills to achieve the 3ft elevation of commode over pile, with the rate of usage she would have I think the structure could stay put for quite some time because the plants could manage the amount of waste we are expecting and it would prevent her from ever having to handle human waste which is a HUGE plus in her book. Some setbacks for the site are that we would have to establish the willow plants so it wouldn't be functioning until next summer and the one perfect spot we had chosen was later vetoed due to "how nice the view is," the majority maintenance would also happen in the first year between establishing the plants (would require moderate watering and full sun) and building the structure, the following years would only require pruning of the willows and weekly sprinklings of sawdust. You could also sprinkle sawdust after every other use but since too much sawdust could inhibit decomposing it would be best for this site to just assign that task to someone to ensure the nitrogen-carbon ratio stays at a healthy balance. 

In my research I found a few species of willow which would work for her climate but I am recommending she plant the salix Exigua because it is native to California, can tolerate seasonal flooding, requires full sun to filtered shade, and is available for purchase in California for $7.99 for a 1-gal plant. Another plant that would work great for her site is the Calisteman, it is drought-resistant, requires full sun to partial shade, attracts hummingbirds and is deer resistant. Both of these plants would require some time to establish but once they are the tree bog would help them thrive and create a nutrient cycle which would drastically limit water usage, decompose waste and help the eco system thrive. 

    Our waste is having a detrimental affect on the earth and its inhabitants, today we flush our waste and expect others to deal with it but, as stewards of the earth it is our responsibility to come up with solutions which are ecologically sound. Every other species on the planet redeposits their waste into the earth for it to be used again, why should we be different? Human waste is not a topic people are too keen on talking about but it is a very important one and one that must be addressed as our population is only increasing and the dead zones in our oceans expanding. It is up to us to get creative and find solutions that work for us AND the environment. Composting toilets present such a great opportunity for us to change one small thing in our life and make one big change within the world. Your urine can help fertilize crops, your poop can help amend soil and add nutrients to the earth, that is how we were meant to interact with the world around us and the longer we consider flushing our waste down our porcelain thrones in potable water a viable solution, the bigger the problem we face will be.