Composting toilets are extremely rare in the United States, but the silent infrastructure crisis and the inherent unsustainability of standard flush toilets are reason enough to consider building them more often.
When most people hear about composting toilets, they probably think of large-scale, passive composting systems found at remote campgrounds or trailheads. While passive composting toilets can be effective, often slightly better than pit toilets, more high-tech and efficient approaches are now available. What all these new systems have in common is urine diversion, colloquially known as pea-cycling.
diversion of urine
Urine diversion is by no means a high-tech concept. If you understand the basic biology behind composting, this is a very obvious approach to composting human waste.
Composting is the natural decomposition of organic matter by microorganisms. These microorganisms thrive when the feedstock (the material being broken down) has a carbon-to-nitrogen ratio of approximately 30 to 1 and moisture levels between 40 percent and 60 percent.
Urine is a liquid with a high nitrogen content, which can interfere with the composting of other organic materials. Furthermore, urea in urine is broken down into ammonia, killing microorganisms that break down waste products. However, when treated separately, the urine has great value as a fertilizer.
liquid gold
Urine also doesn’t need to be composted. valuable fertilizer. It’s 95 percent water, and the remaining 5 percent is made up of high nitrogen content, as well as phosphorus and potassium, which can overload your compost pile.
The nitrogen-phosphorus-potassium (NPK) ratio in human urine is 10-1-4, which is very large. healthier for garden soil Better than 10-10-10 commercial fertilizers sold as “balanced”.
rich earth
of Rich Earth Research Institute We are committed to reusing human waste as a resource through research, education, and regulatory advocacy. Their research includes studies such as the impact of commercially available mineral fertilizers, the value of human-derived fertilizers, ways to improve urine-derived fertilizers, and social surveys to understand barriers to human waste reuse. We also offer tours, workshops, and conferences for farmers, engineers, and others interested in pea cycling.
But perhaps their most important work is advocating for a regulatory framework that allows for widespread recycling of urine. The World Health Organization recognized Urine is a safe and useful fertilizer that requires little treatment. However, most jurisdictions in the United States do not recognize urine separated from the source as a separate substance from wastewater or sewage.
In collaboration with Rich Earth Institute Recodeis working on Update the Uniform Plumbing Code (UPC) Other policy and regulatory documents including best practices for urine recycling.
what you can do
If you plan to build a composting toilet, choose a design that diverts urine. But if a composting toilet isn’t in your future and you want to pee in the garden, we won’t judge you.
To increase privacy, many people in homesteading cultures have supplementary bucket toilets or portable urinals in their bathrooms. The collected urine is diluted and used as liquid fertilizer for the garden. People who have regular plumbing and no space for an additional toilet can purchase flush toilets that divert urine. However, if you live in the Brattleboro, Vermont area, consider the following: donate Your urine will be recycled.
Editor’s note: This article was originally published on January 29, 2020 and updated during January 2025.
