Waste Management

Composting Toilets Relieve Need to Flush Clean Water

Nutrient Networks takes ecological view to deal with human waste


The use of sewer, highlighted above, and septic systems to deal with human waste generate pollution and wastewater. Septic systems leak waste into groundwater, which can contaminate onsite drinking-water wells or other nearby wells. (Moss Design)

Today’s composting toilets are not the equivalent of a port-a-potty stashed away in the basement. In fact, some models look similar to everyday commodes, but they all save water for drinking and showering. And they don’t stink, require chemicals to clean, or flush or discharge human waste into the natural environment.

The average single-family home in the United States uses about 88,000 gallons of water annually, according to a 2016 study. Some 24 percent of the daily usage, or about 30 gallons, is flushed down the toilet.

Despite federal regulations requiring that toilets use only 1.6 gallons of water per flush, toilets made before 1992 may be using up to 7 gallons a flush. Even with the reduced 1.6-gallon standard, however, a single toilet flushed five times a day will waste nearly 2,340 gallons of potable water annually.

“Unfortunately we don’t price or value water the way we should,” said Conor Lally, an ecological sanitation planner and installer with a background in watershed science and ecological design. “Composting toilets just make more sense because you are not creating that wastewater to begin with. It’s a better way of managing that material.”

The Providence resident and New York native co-founded Nutrient Networks to focus on “root cause solutions to the economic and environmental problems associated with conventional water, wastewater, and food systems.”

Those behind this fairly new endeavor, including co-founder Danilo Morales and composting toilet guru and vermicomposter Ben Goldberg, design, build, and install composting and management systems that divert valuable nutrients from the waste stream, reduce pollution, and help close the food-nutrient cycle.

They believe such efforts play a critical role in the larger movement toward localizing energy, water, and food, building soils, and improving public health.

Treating human waste with septic systems and wastewater treatment plants is costly in both energy and resources, contributes to soil and water pollution, contaminates drinking-water supplies, and leads to combined sewage overflows into important water bodies.

As the human population continues to increase — 7.6 billion and counting — planners and public-health professionals are beginning to recognize the need for environmentally sound human waste treatment and recycling methods. The notion of converting human waste to a usable resource, however, isn’t a new concept.

Wasting a resource
Lally’s first job out of college — he graduated from Boston University with a master’s degree in energy and environmental analysis — was working for John Todd Ecological Design doing constructive wetlands for wastewater treatment in Woods Hole on Cape Cod. His interest soon shifted to dry sanitation and composting toilets. He began working with Goldberg.

Lally said Todd’s ecologically designed wastewater treatment systems still have a place, “but what we started to realize was it was a smarter way of doing a stupid thing, because at the end of the day we were still facilitating people pooping in their drinking water.”

“It was a sexier way of cleaning it up, but at the basis of it still was maybe not the best option, so I became more interested in not creating the problem to begin with,” he continued. “I think that’s what composting toilets and ecological sanitation is all about.”

The work of Nutrient Networks includes educational workshops, graywater management and rain harvesting, urine diversion planning and installation, and composting toilet planning and installation.

Originally commercialized in Sweden, composting toilets have been an established technology for more than three decades, but there’s still plenty of hesitation when it comes to installing one in a home or making them part of 21st-century building codes. In fact, one of the major obstacles holding back composting toilet use in the United States are regulations geared toward flush systems and their waste of water.

Composting toilet systems — sometimes called biological toilets, dry toilets, or waterless toilets — contain and control the composting of human waste and toilet paper. And, unlike a septic system, composting toilets rely on aerobic bacteria to break down wastes, just as they do in a backyard compost pile.

Lally said the next step for ecological sanitation is taking it to the watershed scale or community scale to have a broader positive impact on the environment, most notably on water bodies.

“That hasn’t necessarily happened yet, but that’s what we are hoping to do,” he said. “To kind of make the next jump with all of this.”

Nutrient Networks travels across New England installing residential composting toilets and designing and building more complex wastewater systems. The company, for instance, has installed two composting toilets at the Listening Tree Cooperative in Chepachet, R.I., and seven at Round the Bend Farm in South Dartmouth, Mass.

Lally has also traveled to New Zealand and the Grand Canyon to work on ecological sanitation projects.

The state of Rhode Island installed its first composting toilet during a major renovation of the Misquamicut State beach pavilion in the 1990s. Today, there are more than 20 composting toilets at state parks, beaches, and campgrounds.

Shoveling humanure
Composting toilets only treat human waste, so a separate wastewater system, either a septic tank or sewer hookup, is needed to handle dish washing, laundry, and bathing.

Composting toilets can be retrofitted into an existing bathroom or incorporated into new construction. They come in many shapes and sizes depending upon the number of users. They can be homemade, custom-built, or manufactured.

The way they work isn’t “dissimilar from your backyard composting,” Lally said. “It relies on the same science, but there is the element of potential pathogens that has to be taken seriously. But with enough retention time it can produce a very safe, nutrient-rich compost that can be worked back into the soil rather than flushed out into our water bodies.”

He said maintenance of most systems isn’t difficult or time consuming, but “very important to do.”

The most important thing when selecting a composting toilet is to choose a system that adequately meets your home or business needs, according to Goldberg, who has been installing composting toilet systems in private residences, businesses, and public facilities across New England since the 1980s.

Lally noted model and system choices come down to preferences.

“There’s a lot of different systems out there so someone might be more interested in being more engaged and want to actually have a very simple bucket-style system where they are more frequently bringing a bucket of humanure out to a secondary compost site,” he said. “Other people might not have any interest in having that level of involvement in managing their own humanure.”

He said some of the more advanced, large-capacity systems such as the Phoenix and Clivus Multrum have very simple maintenance tasks and everything happens within a basement tank. Regular management of most composting toilet systems requires adding carbon-based bulking material such as pine shavings or saw dust.

“I think it’s good for people to be a little bit more aware and engaged in how humanure can be managed,” Lally said. “We see it as a resource not as a waste.”


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  1. How would these systems work in an urban setting, or multi-family home or condo, where there may not be a basement to store the holding tank, or outdoor space to use the compost?

    • There could be humanure collection service similar to your Garbage, Recycling, Yard Waste services were they can pick up humanure with separate truck curbside in cart labeled ‘Humanure’ and hauled to a composting facility.

  2. I’ve got a self-contained unit in my home in the city. About once a month I open it up, but a lid on the waste bin, and take it out to a composting bin in my yard. Zero odor. Clean, easy. Amazing.

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