Pee-cycling saves water, feeds plants, and helps low-income farmers. What’s not to love?
More than 170 volunteers in the Brattleboro area have contributed urine to the Rich Earth Institute field trials.
For the past few years, a handful of folks up in Brattleboro, VT have been saving their pee in giant tubs. Or rather, they’ve been relieving themselves into the special urine-separating toilets provided at many public events in the small town of 12,000, which collect their potent leftovers into a giant vat, and are then handed over to local farmers. While most people might not enjoy receiving a giant vat of pee, these farmers are delighted with this traditionally repulsive gift. This exchange is part of a pilot program in Vermont, known colloquially as pee-cycling, and it may just serve as a brilliant and effective solution to the world’s waste disposal and agricultural woes at once.
Most fertilizers help to replenish nitrogen and phosphorous in soils. To produce the amount of nutrients needed in fertilizers, manufacturers often use synthetic processes and some very intensive, volatile mining practices. But every day, gobs of these valuable substances found in urine are just flushed away. The average American generates eight pounds of nitrogen and one pound of phosphorous per year in his or her urine (more with a higher protein diet). This means that the country’s collective 30 billion gallons of urine could produce the equivalent of 9 billion pounds of synthetic fertilizer annually, enough to grow the wheat for one loaf of bread per day, per person.
Applying urine uniformly to a 5 meter x 5 meter test plot
Human urine is mostly sterile, and save for slight variations in salinity or acidity based on diet (which only affect sensitive plants), makes for an effective, easy-to-distribute fertilizer. But instead of putting urine in the ground, Americans waste three to six liters of water per flush—nearly 1.2 trillion gallons per year nationally—dumping it into sewage systems where, untreated, it feeds algal blooms that choke out other aquatic life and wreaks great ecological damage. Thanks to the 1972 Clean Water Act, the United States now takes great pains to remove urine-based nutrients from wastewater to prevent these algal blooms. However by doing that, they essentially spend a large amount of money just to dispose of perfectly good plant food.
Documented evidence of urine recycling as a farming technique stretches back to 1867 at least, but has really only taken off in Europe over the past decade or so. While there are various Finnish researchers and Swedish enthusiasts promoting pee-cycling on the continent, Amsterdam in particular has set itself at the forefront of the movement. Its water utility service, Waternet, leads public demonstrations on how to use urine-separating toilets to nurture home and roof gardens.
As required by state permit, signs are posted at each field site.
The first American pee-cycling program emerged in 2011, when the U.S. Department of Agriculture provided a grant to the Brattleboro, VT-based Rich Earth Institute to study fertilizers for low-income farmers. The next year, the Institute initiated their Urine Nutrient Reclamation Project. Just a handful of volunteers collected 600 gallons of urine and started experimenting with different dilutions and delivery systems on a local farm’s hay field. The direct application of urine resulted in dramatic gains for the hay farmer, and the project had to ramp up to meet the new surge in demand; by 2013, they’d developed a base of 170 volunteers and collected over 3,000 gallons.
The team has been experimenting with months-long storage and solar-powered pasteurization strategies to prevent incidental contamination, and they now regularly serve four local farms with an estimated annual 6,000 gallons of urine. One of the major concerns with urine fertilization is the presence of medications in modern human waste, and so the Rich Earth Institute has recently begun a series of tests to gauge the edibility of carrots and lettuce grown with the technique.
The largest number of hay bales were harvested from the strip on which undiluted urine was applied at a rate of 100 lbs of nitrogen/acre.
Pee-cycling is one of those mind-bendingly simple ideas that seems like it shouldn’t work. It’s just so obvious—if urine was a good fertilizer, wouldn’t we already know about it? The reticence probably comes from a number of places: Ick factor, overthinking the problem because urine seemed too easy, and hesitation to engage with such a seemingly pre-industrial and visceral material.
Given that Americans have explored urine sterilization and utilized biosolids, (compacting whole sewage into a sludgy fertilizer) for years, it’s a wonder that it’s taken this long to start a pilot program for pee. As research continues at the Rich Earth Institute and in private homes inspired by their efforts, the word of pee-cycling will spread—hopefully, one day all proud Americans will store vats of their own urine in their homes.