According to the Worldwatch Institute, a single compost toilet can save well over 2,000 gallons of water each year at a rate of just four uses per day.
Long-time Topanga resident Sue Moore and her family have maintained three compost toilets for about ten years (since 2009). Suffice it to say, she has saved Topanga a lot of water and created bona fide, sanitized compost for use in the garden.
A compost toilet system consists of a toilet that retains human waste in a sanitary manner and a compost bin in which the waste from the toilet–“humanure”–is processed into compost.
According to Moore, the best design for the toilet component is the simplest: a cabinet with a five-gallon bucket inside, which is fitted under a toilet seat and layered with wood dust and coffee grounds to manage odor.
In addition to water conservation, compost toilets come with many other benefits. Moore mentioned that “you never have a clogged toilet, and you never hear the flushing sound.” She went on to stress the importance of composting as a way to be “responsible for where everything goes.”
She referenced a 2013 study conducted by Rebecca Ryals and Whendee L. Silver, showing that a thin layer of compost, spread over a quarter of California’s rangeland, could absorb three-quarters of California’s annual greenhouse gas emissions.
Moore first became interested in compost toilet systems more than a decade ago when she was attending a course on solar energy in Hopland, California. This interest turned into a hobby when her son and his friends were given a geography project in school that asked for a presentation on Earth’s atmosphere, biosphere and hydrosphere: the compost toilet pertained to all three.
The first toilet they built did the job, and she went on to build three new toilets over the next few years. The only major change she’s made to her method is the size of the toilets’ accompanying compost piles: the first one was too small and didn’t reach the high temperatures (upwards of 140 degrees Fahrenheit)* that her current bins do, which are both more than four cubic feet in size. (The compost bin is at least 64 cubic feet in size – not 4 cubic feet)* (Temperatures reached in the compost bin, in our climate, are 140-160 F, with the addition of time, complete sanitation is achieved.)*
The second toilet nicknamed “The Pumpkin,” includes an outhouse-style building that is fully collapsible. Moore has taken the colorful plywood structure to a wedding, a local circus camp and the Topanga Earth Day Festival. At this festival, The Pumpkin was set up as an exhibit, but its nearness to the other, chemical, portable toilets found many festival goers attempting to use the more attractive Pumpkin’s facilities.
A major source of inspiration for Moore’s composting projects is The Humanure Handbook by Joseph Jenkins, which, since publication in 1995, has become a manifesto for composters around the world. In 2009, the book received praise from the New Yorker stating that “the methods outlined within [the book] have the potential to change the ecological fate of the world.”
Though traditional Chinese fertilization methods include composting human waste, the compost toilet system is relatively novel to the Western world. Modernized toilet companies like Biolan and Sun-Mar are gaining popularity, but Moore says they “don’t really sanitize anything, they’re expensive, and they break often.”
Aside from the drawback of unnecessary energy usage (the simple toilet design described above uses no power or water), these high-tech toilets generally employ a slower method of composting that can take months or years to fully treat human waste. (The complete process takes about 2 years; one year to collect and fill the 64 cubic foot compost bin for a family of 4, it reaches high temperature with the activity of thermophilic bacteria, then cools down after about a week or 2 – then for an additional year, the compost cures, cools off and other life forms such as sow bugs and worms move in to continue the compost process – the finished compost can be used for gardening or for growing food.) What they lack is the heat required to sustain thermophilic bacteria, which, in sufficiently hot compost, can sanitize and process human waste down to less than 30 percent of its volume in just a few weeks.
The simple toilet design that Moore uses allows for this superior compost style. Moore feels that such toilet systems offer a powerful way to combat excessive water usage and to utilize an often-overlooked resource: when properly composted, human waste, along with food scraps and other materials, becomes rich fertilizer.
According to Moore, Topanga’s ample outdoor space is ideal for housing compost bins and spreading compost out as soil.
She mentioned a possible starting place for broadening humanure composting in Topanga: “a public composting toilet system in the center of town, by the creek, where residents can experience a live, working model of the system in action and can learn how to do it themselves.” (“Humanure”, and animal manure is collected, tended and managed, the finished product is a rich “Compost” that can be used for gardening &/or growing food – this is a correction to the article where it says the finished product is called Humanure.)*
Moore believes that a public toilet pilot project would keep Topanga cleaner, as well as inform the public of the feasibility of composting toilets for home use. She plans to seek county support for the project, would oversee its maintenance and demonstrate the benefits of humanure composting.
Those interested in the public toilet project may contact Susan Zwilling Moore on the Topanga Local Facebook page or send a private message to Sue Moore on Nextdoor Topanga with questions or ideas. (I am happy to share my experience with interested people once they read the book, and have a complete understanding of the process.
My mentor, Joe Jenkins has over 30 years of experience in Pennsylvania, he wrote the Humanure Handbook, and he has been available for my questions over the years. He donated 10 copies of his book that were distributed at the Topanga Earth Day, when it was happening. The latest edition of his book is here . An older edition of his book on pdf and free, is here*
*Editor’s Note: Please see the comment section for some clarifications made to this article by Sue Moore.