Frequently Asked Questions

Why is the Rich Earth Institute collecting urine?

How much fertilizer is there in urine?

Isn’t using urine dangerous?

I would like to contribute urine for the Urine Nutrient Reclamation Project. How do I get involved?

Will the urine be treated before spreading it on the field?

What about pharmaceutical residues in the urine?

Is this project legal?

What will you do after the hay is harvested?

What is the next step for the Rich Earth Institute?

Are there any other urine fertilizer studies in the US?

What is source separation?

What is a urine diverting toilet?

Where can I learn more?

Why is the Rich Earth Institute collecting urine? The average person flushes the toilet five times a day, and four of those times are just for urine. This means that 80% of our flushwater—or over 4,000 gallons of clean water each year per person—is used just to get rid of urine! That is a lot of clean water used to transport ‘liquid gold’ into the sewer, where it becomes pollution. If we save it instead of flushing it, we can harvest a valuable resource that we can use in agriculture.

How much fertilizer is there in urine? On average, we each produce about 8 pounds of nitrogen and almost 1 pound of phosphorous in a year’s worth of urine. This is nearly enough to grow one year’s worth of food. Surprisingly, there is very little nitrogen in feces, and only a relatively small amount of phosphorous.

Isn’t using urine dangerous? No. Urine is commonly sterile–the diseases that people associate with human waste are found in feces, not urine. Urine has been used throughout time as potent fertilizer, as well as for various industrial and even medicinal uses.

I would like to contribute urine for the Urine Nutrient Reclamation Project. How do I get involved? Please contact Kim Nace at to join the project. Kim will send you the guidelines for collecting your urine. You will need a sealed 5-gallon container to store your urine, which the Rich Earth Institute can supply. If you supply your own container, please make sure it is food-grade and is washed clean of any previous contents.

Will the urine be treated before spreading it on the field? Urine is practically sterile, but since we will be using some urine from urine diverting toilets, it is possible for a small amount of feces to end up in the urine collection bowl. Therefore, to ensure that no pathogens are transmitted to the field, we will sanitize it prior to application. We are trialling two methods: pasteurization and long-term storage at room temperature. To pasteurize, we will heat the urine to 70 degrees C (158F) in small batches using a solar heater. The long-term storage method is a newer technique, and it relies on the fact that stored urine becomes very alkaline, (because the urea transforms into ammonia, raising the pH to above 9.) Over time, the alkalinity destroys any pathogens that may be present. One month is sufficient to sanitize urine that is used to grow animal feed. We are collaborating with scientists at the EPA Research & Development office in Cincinnati to test the effect of long-term storage over a range of conditions. We will be running experiments in the future to explore further methods for sanitizing urine while maximizing its fertilizer potential.

What about pharmaceutical residues in the urine? When we take prescription or over-the-counter drugs, a portion of the dose passes through us unchanged and is excreted in our urine. When we use flush toilets that are connected to sewers, these residual drugs pass largely unchanged through the treatment plant in about twenty-four hours and then go directly into rivers, lakes, or the ocean, where they can harm sensitive aquatic life and end up in our drinking water. If we spread the urine on agricultural land instead, the robust soil ecosystem has a chance to break down the drugs and biodegrade them over a much longer period of time, greatly reducing or eliminating their levels before they ever reach a body of water. In this way, soil application is a great improvement over current practice. On the other hand, plants have the ability to absorb some pharmeceuticals, which could potentially affect people eating crops grown with urine. We plan to investigate pharmaceutical levels in crop plants and, if necessary, test methods of removing pharmaceuticals from urine before using it as a fertilizer.

Is this project legal? Yes. Prior to starting this research project, the founders of the Rich Earth Institute met with members of Vermont’s Agency of Natural Resources (ANR), which has oversight of wastewater matters, to review all areas of potential regulatory concern, including environmental quality and operator safety. We have received authorization to use up to 800 gallons of urine as fertilizer this year, after sanitizing it to destroy potential pathogens.

What will you do after the hay is harvested? After analyzing and documenting the results of using up to 800 gallons of urine for this initial project, we will publish and broadly publicize our experience and findings. In the second season (summer 2013), we anticipate expanding the project to several farms. Pending grant approval, we will also begin investigations into the fate of pharmaceuticals and hormones from urine in the agricultural soil environment.

What is the next step for the Rich Earth Institute? The Rich Earth Institute is a research and demonstration organization: We will be publishing our results to add to the growing cannon of knowledge nationally and internationally. We will be presenting educational programs in our local community. We plan to create several formal urine collection demonstration sites. This will include installing urine diverting toilet systems and waterless urinals. These systems will demonstrate changes possible to the current sanitation infrastructure. We also will continue to collect urine for REI’s future fertilization experiments at the demonstration sites.

Are there any other urine fertilizer studies in the US? To our knowledge, the Rich Earth Institute’s study is unique in the United States. Researchers are working on a variety of other nutrient reclamation questions, but we are conducting the first public field trial for urine as a fertilizer, and the first community-sourced urine nutrient reclamation project. Because of our rural southern Vermont setting, the significant efforts of Vermont citizens and state government to preserve the environment, and the generally independent thinking attitude of the larger community, we are in a prime setting to move this problem towards solution. In addition to our scientific contribution, the Rich Earth Institute will be documenting the sociological experience of our local participants. We will survey our contributing population and monitor the changes in attitude and perception of human waste management.

What is source separation? Source separation is the practice of keeping urine and feces separate from the rest of the wastewater stream. This allows for the beneficial reuse of the human waste, and results in wastewater that is much easier to clean up. Some source-separation systems harvest both the urine and the feces, while others capture only the urine (which contains the great majority of the fertilizer value) and flush the feces into the existing wastewater system. Some source-separation systems involve composting toilets, and many employ urine-diverting toilets (see below.)

What is a urine diverting toilet? A urine diverting flush toilet has a toilet bowl that has two separate bowls, one in front for urine and one in back for feces. The urine is flushed separately and can be collected for reuse. A urine diverting dry toilet uses no water for flushing—it has a front bowl for urine, and then a chute in the back for feces that leads to a composting chamber. These are not yet manufactured in the US but can be imported from Europe as full porcelain molded toilets, or as a plastic diverting insert which can be attached to a dry composting toilet.

Where can I learn more?

The Big Necessity, by Rose George, is a great introduction to the current state of sanitation, and has inspired more of our board members than any other resource.

Liquid Gold, by Carol Steinfeld, is a short and entertaining, yet profoundly informative book about the uses of urine throughout the ages, including practical details on its modern use as a fertilizer by home gardeners and farmers.