System Shift Series: Cape Cod Homeowner Turns to Composting Toilets to Cut Water Use and Protect Local Ecosystems
System Shift is a new story series focusing on Cape and Islands homeowners who have I/A systems and/or are practicing alternative ways of dealing with human waste. The series also puts a spotlight on pioneers in the world of advanced treatment. What’s it like to have an I/A system? How does it help the local mission to be better land and water stewards? We’ll tackle these questions and more in hopes of helping “shift” the way we see all the moving pieces of Cape Cod’s wastewater puzzle.
By Amy DuFault, MASSTC Communications
COTUIT, MA. — Long before Sara Molyneaux worked in chemical engineering, as an environmental advocate, or a homeowner rethinking the way wastewater works, she was a child with a vivid imagination and a passion for the outdoors.
Growing up as an only child, she spent hours outdoors alongside her favorite backyard elm that became a kind of companion. “It was always full of indigo buntings and goldfinches,” she recalled fondly.
That early bond with the natural world carried her through a biology degree and into a research career exploring fermentation using seaweed and freshwater plants. It also pulled her into environmental policy and community action, including 25 years on the board of the Conservation Law Foundation, where she focused on protecting New England’s waterways and coastal ecosystems.
So when she and her husband began renovating their 1915 Cotuit home—a property they bought in 1989, when the basement still had a dirt floor—Molyneaux saw a chance to weave sustainability more deliberately into the structure of daily life. By the time the major renovation wrapped in 2012, the couple had chosen an unconventional but deeply intentional upgrade: replacing all three of their toilets with Phoenix-brand composting toilet systems.
“It was really the only choice that fit with how we live,” she said.
One of the Molyneaux home’s Phoenix composting toilets
A Sustainability Path Years in the Making
Molyneaux’s decision wasn’t impulsive. Throughout her environmental work, she had seen successful examples of waterless toilet systems around the region.
The first one that stuck with her was at the Doyle Community Park and Center in Leominster, a LEED Gold–certified building owned by The Trustees. She remembers being struck by how seamlessly the Clivus composting toilets worked, how much water they saved and pollution they prevented.
Later, she would visit Hale Education in Norfolk County, where the nonprofit’s Outdoor Learning Adventures camp—serving more than 16,000 children each year—relies in part on Phoenix composting toilets.
A sign in one of the composting toilet bathrooms
“That really sealed the deal for me,” she said. “Sixteen thousand kids using those toilets, and they’re saving goodness knows how much water.”
Her exposure stretched back even further, to a visit more than a decade before to The Green Center in Falmouth, the successor to the visionary New Alchemy Institute. There, she had met longtime educators Hilda Maingay and Earle Barnhart who demonstrated Phoenix systems as part of their ongoing mission to build “ecologically derived human support systems.” Their work, spanning food systems, renewable energy, and sustainable housing, made a lasting impression.
“All those pieces came together over the years,” Molyneaux said. “So, when it came time to renovate, we felt ready.”
Woodshavings make ideal aggregate for composting toilets
Three Toilets, One Decision
Installing just one composting toilet in a house with three bathrooms made little sense to the couple. The systems cost around $8,500-$9500 including the composter, toilet, and all parts. Since the renovation touched every part of the house, they committed to installing a waterless Phoenix system in each bathroom on the ground floor.
Getting permission was surprisingly simple.
“We just went to the Town of Barnstable and asked how to get the OK,” she said. “They just said, ‘Just put them in!’”
They then hired Ben Goldberg, a longtime composting-toilet installer known throughout New England for his work in residences, camps, and public buildings. Goldberg helped integrate the Phoenix systems into the renovated basement, where the composting units now sit—quiet, odorless, and, as Molyneaux likes to point out, almost unnoticeable.
“You don’t smell a thing,” she said. “Aerobic decomposition and the ventilation fan take care of everything.”
Another composting toilet in the Molyneaux home. The can on the left is full of wood shavings for post-bathroom use and sprinkled down into the toilet + composter located below.
The toilets also require no flushing, saving thousands of gallons of water each year—especially important on Cape Cod, where groundwater and coastal embayments are extremely vulnerable to nitrogen pollution.
“We have microbes in there that have everything they need for composting to keep nitrogen out of the marine embayments all around us,” Molyneaux said.
In addition, every few years, they use the compost “tea” collected from the system to fertilize the property’s larger trees. Clean-outs are rare. It’s been “suggested” they do it about every three years though Sara says it turns out to be more like every ten, according to guidance from Maingay, Barnhart, and Goldberg.
The Molyneaux family home in Cotuit
Visitors, Reactions, and a Changing Mindset
The system generally fascinates guests, though it occasionally catches someone off guard.
“Our son told us they had one friend who was actually afraid to use it,” Molyneaux said with a laugh. “They got over it, but it reminds you that these systems are still unfamiliar to many people.”
But Molyneaux believes perceptions are shifting, especially as water scarcity and environmental concerns grow nationwide.
“We live in an area that should be treated like a national park, not a dumping ground,” she said. “This shouldn’t be fringe technology.”
Sara Molyneaux in her backyard overlooking Cotuit Bay
Looking Ahead
To Molyneaux, composting toilets aren’t extreme—they’re practical, accessible and affordable. They are also deeply aligned with the realities facing Cape Cod, where nitrogen pollution from traditional septic systems is heavily impacting the health of the region’s ponds, bays, and estuaries.
“I wish this technology would be more supported and allowed to take off,” she said. “The price is low, and you don’t have to take such dramatic action to have one.”
She paused, resting a hand on the composter—a machine that, in her home, has become almost as ordinary as a kitchen appliance.
“It’s just such an easy and inexpensive way to save the Cape’s bays and ponds from becoming a toxic mess,” she says.
Read more from the System Shift series here.
