The short version
This is an advocacy talk, not a scientific paper. Earle Barnhart and Hilda Maingay of The Green Center presented these slides on June 18, 2024 at the Waquoit Bay Reserve's Cape Coastal Conference to make a case for urine diversion. They ask why Cape Cod's ponds and bays keep getting more polluted, and answer that the cause is the nitrogen in human urine, which reaches the water through septic systems and groundwater. They argue that collecting urine separately instead of flushing it would remove most of that nitrogen at a fraction of the cost of sewers or I/A (nitrogen-reducing) septic systems, and they list steps towns could take now. The slides were not peer reviewed and give few sources for their numbers, so treat every figure as the presenters' claim. This summary covers only what the slides show.
What the report covers
The slides make an argument in steps rather than reporting a new experiment, moving from the problem to the cost of current fixes to a proposed alternative.
- The problem: urine from septic tanks moves with groundwater through fresh ponds to coastal estuaries, with photos of algae blooms, fish kills and red tide.
- A cost comparison, in dollars per pound of nitrogen removed, for sewers, I/A septic systems, incinerating toilets, a urinal-plus-toilet combination and a urine diversion program in Brattleboro, Vermont.
- A look at what sewers and I/A systems use up: fresh water for flushing, nutrients and energy, and what they add in greenhouse gases.
- A critique of state nitrogen regulations (MassDEP) as resting on 22-year-old studies and estimates.
- A tour of urine-diverting toilets and urinals with price tags, ways to store, pasteurize, compost or farm-apply the diverted urine, and the costs of community-scale handling.
- A closing list of actions: incentives for homeowners and exemptions from sewer or I/A requirements.
What they found
- Small volume, big share of the nitrogen. The slides say urine holds about 80% of the nitrogen in household waste but only about 1% of its volume. One person's urine is shown as roughly 120 gallons and 8 pounds of nitrogen a year (Barnhart & Maingay, 2024).
- Sewers and I/A systems cost far more per pound. The slides give $300–$431 per pound of nitrogen removed for central sewers and $181–$723 for I/A systems, against $60 for incinerating toilets, $50 for a urinal paired with incinerating toilets and $35 for a Brattleboro, Vermont urine diversion program. They put the cost of removing one person's urine nitrogen at about $2,400 a year by sewer or I/A (Barnhart & Maingay, 2024).
- How much diversion could remove. The presenters say urine diversion can cut nitrogen by 80% and phosphorus by 55%, and that composting toilets can cut nitrogen by 90% and phosphorus by 99%. The slides show a monitoring chart but do not name the source (Barnhart & Maingay, 2024).
- Water and climate side effects. They estimate flushing uses about 6,000 gallons of water per person a year, mixed with 6,000 gallons of greywater (shower, laundry and cooking water) into 12,000 gallons of wastewater. They say waterless urinals save about 4,000 gallons and composting toilets about 6,000, and that sewers and I/A systems give off most of the nitrogen as gas, lose the other nutrients and add greenhouse gases (Barnhart & Maingay, 2024).
- Where the nutrients come from. The slides say about 460 million pounds of food and 6 million pounds of fertilizer (mostly for lawns and ornamental plants) are trucked onto the Cape each year, and that people excrete 98% of the nutrients in the food they eat (Barnhart & Maingay, 2024).
- What to do with the urine. Options shown are storage in tanks, use in the household's own garden with no treatment required, pasteurizing it (176°F for 90 seconds, about $0.01 a gallon or $1.20 per person a year) for use on commercial farms, or composting it with food and landscape waste at 151°F for 3 days. Trucking one person's yearly urine to farms up to 70 miles away is put at about $17 (Barnhart & Maingay, 2024).
- Price of the fixtures. Urine-only fixtures range from about $80 for a simple funnel-and-jug set to $700 for a flushing urine-diverting toilet. Composting and incinerating toilets run from roughly $990 to $8,700, with installation not included (Barnhart & Maingay, 2024).
- What they ask for. The presenters call for subsidies, grants and loans for installation and infrastructure, paid for by spending less on sewering, and for exemption from sewer or I/A requirements where septic tank effluent is 19 mg/L of nitrogen or less, or where all human waste is removed from the waste stream (Barnhart & Maingay, 2024).
What it means for Waquoit Bay today
The talk was given at the Waquoit Bay Reserve's own conference, and the slides show the south coast of the Upper Cape, where Waquoit Bay sits, as an example. It covers Cape Cod as a whole. It is an advocacy talk, written to persuade, and its cost and removal figures are the presenters' own, with few cited sources. Read them as a case for further testing rather than settled results. Falmouth has since started a state-funded pilot of urine-diverting toilets in about 25 homes, including some in the Waquoit Bay watershed, which is meant to produce local data (see the pilot moving ahead and the town's fall 2024 update).
Why it matters here: septic systems are the largest source of the nitrogen that feeds algae in Waquoit Bay (see where Waquoit Bay's nitrogen comes from). The talk puts forward a different way to cut it, by separating urine at the source, alongside the sewers and I/A systems that towns are already planning around. It also raises lawn fertilizer as a second, smaller source; for evidence on one response, see fertilizer ordinances. Whether the savings hold up in Falmouth and Mashpee is what pilots like Falmouth's are meant to show. Our conference roundup lists all the talks from the 2024 Cape Coastal Conference, with slides and videos.
See the presentation
Barnhart, E., & Maingay, H. (2024, June 18). *Cape Cod urine trouble* [Conference presentation slides]. Cape Coastal Conference, Waquoit Bay National Estuarine Research Reserve, Hyannis, MA, United States. https://waquoitbayreserve.org/wp-content/uploads/Urine-Trouble_Maingay_Barnhart.pdf
License: The slides carry no license statement and include images and figures from other sources, so we link to the copy on the Waquoit Bay Reserve's website and do not host it. This is a conference slide deck, not a peer-reviewed paper. This summary is based only on the slides, not on the talk. A video of the talk is on YouTube. The card image is a title card made from the citation.
Drafted with AI assistance from the linked source.
