Joe Jenkins literally wrote the book on humanure—The Humanure Handbook—a 255-page guide to composting human manure, including building your own toilet and turning your own excrements into rich, crumbly brown humus for your garden. Originally published in 1995 and now in its third edition, The Humanure Handbook has sold more than 55,000 copies in the US alone, with translations in whole or in part in sixteen languages. The second edition, published in 2000, was winner of the Independent Publisher 2000’s Outstanding Book of the Year Award and deemed “the book most likely to save the planet!” Jenkins has been a compost practitioner in the United States since 1975 and has grown his family’s food with humanure compost for the past thirty-five years. His website offers videos, instructions and the complete Humanure Handbook free of charge.
When Joe Jenkins is not building, studying, or consulting on compost toilets—he has helped to set up large-scale compost toilet systems in Mongolia, Haiti, and Mozambique—he is a slate roofer by trade. He’s also written perhaps the definitive work on slate roof construction, The Slate Roof Bible, winner of the National Roofing Contractors Association’s Gold Circle Award for excellence in the roofing industry. In other words, he has made himself into a self-taught expert in two of the subjects that have occupied his attention for most of his adult life, and others now turn to him for honest advice and feedback.
Jenkins is a member of and speaker for the U.S. Composting Council, which on January 22, 2015, presented him with the H. Clark Gregory Award for grassroots education and awareness of composting. He spoke with The MOON by phone.
The MOON: What is humanure?
Jenkins: Humanure is human excrement that is recycled for agricultural purposes. The humanure is consumed by micro- and macro-organisms in a compost environment and converted into humus, which is added to soil to feed plants. The plants feed animals—including humans—which produce manure, which is composted by micro- and macro-organisms, and so on, endlessly, in a sustainable cyclical pattern.
The MOON: What about disease pathogens?
Jenkins: The composting environment destroys disease pathogens. That’s the whole reason for running humanure through it. Unfortunately, this is not common knowledge. I did write a book about it, The Humanure Handbook, which is full of citations, in an attempt to inform people. Nevertheless, composting is a relatively young science. It didn’t get off the ground until the 1940s and the World Health Organization (WHO) did its research on it in the 1950s. A man named Gotaas introduced known pathogens into the compost environment and measured whether they survived and, if they died, how quickly and at what temperatures. What he found was that human pathogens die rapidly at temperatures above 55 degrees Centigrade, which is about 130 degrees Fahrenheit. In fact, they rapidly degrade at temperatures above 120 degrees F and even 110 degrees—just not as rapidly. But we’re talking differences of minutes.
For example, a persistent pathogen is the roundworm parasite. The eggs are microscopic and they’re highly viable in moist, warm environments, including sewage treatment plants; including soil. They can retain viability for years. But according to the initial research, using the roundworm eggs as an indicator pathogen, they died rapidly at temperatures above 50 degrees Centigrade, which is easily achievable in compost.
This research was repeated by Richard G. Feachem and others in the 1970s. These studies corroborated Gotaas’s work, so it is now accepted science that human pathogens are eliminated in the compost environment.
The EPA requires retention time in a compost pile of three days at temperatures above 55 degrees C, or 131 degrees F, which provides a wide margin of error for the elimination of human pathogens. So it’s well-established and accepted science, though it’s not commonly known. Through composting, human waste becomes a valuable agricultural feedstock—and of course, there’s an unlimited supply of human excrement.
The MOON: And what about contaminants like viruses, heavy metals, and other toxins? Does composting eliminate them, as well?
Jenkins: Two herbicides — picloram and clopyralid — produced by Dow Agrosciences—are known to be persistent in compost and will actually contaminate and potentially ruin an entire composting business. I believe that Monsanto’s RoundUp decomposes, but there are a couple other made by Monsanto that don’t.
There is also the issue of pharmaceuticals—and this is a new issue because we never excreted the amount of pharmaceuticals we’re excreting now. Many are degraded in the compost cycle, but some are not. The research on pharmaceuticals is just now starting to be done. Most of the research is done in labs, which simulate a compost environment, but typically only hold the compost for thirty days. That’s not the same as retaining compost for a year.
If it’s your personal compost, and you think your humanure might have some active pharmaceuticals or other contaminants in it, use the compost to plant trees, or bushes, or flowers—anything you’re not going to eat.
The MOON: How did you become interested in humanure?
Jenkins: I became interested because when I first moved to this property in northwestern Pennsylvania there was no electricity. I lived off the grid for ten years—not necessarily because I wanted to, but because it was too expensive for the electric company to put in half-a-mile of lines and poles for a single customer. Of course without electricity, you can’t pump water, so I had no flush toilet. That was thirty-five years ago. I had experimented with compost toilets previously because I’d had no electricity at a prior location, and no flush toilet at a third. Altogether I’ve been making compost for forty years—and most of that time using humanure as a composting feedstock.
The MOON: You say that your composting toilet may be the only toilet in the world that doesn’t collect waste. Why not?
Jenkins: Because the material that’s collected is recycled and nothing that’s recycled is wasted.
The MOON: That’s a pretty unusual concept in our culture.
Jenkins: It is. Sometimes it’s very frustrating when people refer to something useful as waste. Waste is something we throw out and discard with no further use. It ends up in our landfills. That’s why I had to come up with another word for human excrement, which people are in the habit of calling “human waste.” That’s a misnomer. Humanure tells us its value.
We live in a culture where bodily excretions are assumed to be without value—or, indeed, pathogenic. But humanity has known the value of human excrement for millennia. Particularly in the Far East—in China and neighboring countries—where they’ve recycled human excrement for at least four thousand years. Westerners, too, used to recognize its value. We called it “night soil.” I don’t know what they called it in the Far East, but they used to collect it and pay people for their toilet contents because it was fertilizer. In the U.S. we pay to get rid of it.
The MOON: Haven’t people been trying to keep human urine and fecal material out of their homes and gardens for centuries, if not longer?
Jenkins: That’s a common misconception. You see, no one’s talking about using fecal material in a garden. It’s being used to feed micro-organisms in a compost environment. Just like people used to feed their spoiled milk and food scraps to the pigs—what they called “slopping the pigs.” The pigs would eat the slops; the people would eventually slaughter and eat the pigs. People didn’t think they were eating pig slop.
It’s the same with feeding fecal material to the compost organisms; you’re not putting it in the garden. That’s exactly what you’re not doing. You’re putting in the compost environment, where it is being digested by micro- and macro-organisms to create humus. The humus is what’s put in the garden. The final product doesn’t remotely resemble the original.
The MOON: But can’t some components of excrement—such as tomato seeds—survive? I’ve used sewer sludge in the garden and had tomato volunteers—because the seeds survived tertiary sewage treatment…
Jenkins: Was it composted sludge?
The MOON: I don’t know.
Jenkins: I wouldn’t touch sewage sludge with a ten-foot pole. The only way sludge could become acceptable in a garden is if it’s been composted. Tomato seeds don’t survive the compost environment. Sewage sludge includes everything that goes down the drain—the garage drain, the hospital drain, the industrial drain. It can contain pesticides, heavy metals, old paint, paint thinner, motor oil, medical waste, which ends up in the sewage treatment plant. It’s a highly pathogenic stream that goes through there. The effluent from sewage treatment plants is chlorinated, but the sludge itself can maintain viable pathogens—like roundworm eggs for example. It’s not a very good way to cycle nutrients. I discuss all this in more detail in The Humanure Handbook, which is free online. You don’t have to pay a penny for it.
The MOON: So if composted humanure is perfectly safe, what is the biggest difficulty you face in getting people to transition to a compost toilet?