Composting toilets are often viewed as a wilderness option, an improvement on the basic outhouse but not a truly civilized contraption. But they can make both economic and environmental sense for a wide range of locations—including horse farms, especially in locations where installing a septic system and/or leach field or tying into a sewer are problematic. They are a good choice in locations where water is scarce or where groundwater contamination is a potential problem. As Fairview Gardens Farm has come to appreciate, they make sense almost anywhere.

And in Fairview’s case, installing a Clivus Multrum composting system cost a half to a third of a traditional system, which would have incurred high costs for tying into the local sewer system.

Fairview Gardens is a working organic farm on 12 acres in suburban Goleta, Calif. It is not a stable, but in many respects it is similar to a horse farm. Like a stable, Fairview hosts lots of guests. It raises 75 varieties of fruits and vegetables, making its Center for Urban Agriculture a model for small-scale urban food production and farm-based education. Its community programs include workshops, guided and self-guided tours, lectures, cooking and gardening classes, apprenticeships, and outreach to schools.

Fairview Gardens first considered a composting system vs. a traditional system for environmental reasons. “We live along the coast of California, which is a semi-arid region, and we’ve been through prolonged droughts,” says Matthew Logan, the farm’s administrative director. “We wanted an installation that uses very little water to demonstrate this alternative to the public.”

“There’s nothing about a horse farm that would make an installation difficult.”

And customers are pleasantly surprised. “Most of the people who have used it are quite impressed,” Logan says. “We’ve had other organizations call us about it. Some customers have asked about installing such a system in their own homes.” For some, the biggest advantage, says Logan, is “they don’t want to spend a lot of money to tie into the sewer system.”

How It Works

The farm’s Clivus Multrum system works on the same principle as any composting system. Instead of a waste line, the john simply sits above a holding tank. By adding enzymes and wood chips (which also filter liquid waste, producing an effluent pure enough to water the farm’s organic avocados) to human waste, and adding a dollop of water to keep the mix moist, the waste cooks away to almost nothing—volume is reduced by 95 percent. It will be a total of five years from the time the system was placed in service until the holding tank needs to be emptied of compost, which the farm plans to spread on the farm’s ornamental beds (the city fathers, who don’t trust the use of human manure as fertilizer, won’t allow the compost to be used on the farm’s food crops.)

Each unit can handle a surprising amount of waste. Fairview’s single stall can accommodate 120 uses a day. “It’s not unusual for a dozen or more fixtures to handle half a million uses in a year,” says Clivus Multrum president Don Mills.

It’s a remarkably clean system. The individual Clivus units consist of one to four individual stalls or urinals that feed a collection chamber, which holds anywhere from 1,000 to 1,500 gallons. A fan in the chamber pulls air down and out a vent pipe to fuel and speed the composting process. This also prevents fumes from seeping into the bathroom. The lack of odor helps explain why composting toilets are so popular with customers.

Composting toilets require some minimal but regular maintenance. All compost piles need turning and periodic fuel supplements, such as wood chips. Logan turns the pile about once every two weeks, a 15-minute process, by opening a door on the tank and raking it (Clivus Multrum supplies a special rake for this purpose). To keep the pile sufficiently moist, the system hits it with a five-second spray of water every 24 hours. If a pile starts to cool down—a sign of inadequate decomposition—Logan simply adds more wood chips or adjusts the water supply.

The maintenance is not much different than working with any compost pile. “It’s not something that farm employees would balk at,” says Mills. “They deal with horse manure all the time, and human waste is not much different. Farm employees are not as squeamish about it as is often the case.” Plus, compared to dealing with plugged-up toilets, composting toilets are much, much more pleasant, Logan points out.

The system also requires some simple instruction and education for users. Most important is to avoid throwing anything into the toilet that won’t compost, like plastic or metal containers or cigarette butts. But this is usually a minor issue.

Dollars and Scents

Fairview encountered more difficulties in the permit and planning process than most users. Local regulators were aghast at the composting idea (this is in suburban California, after all). Local commissioners in this sewer-fixated town feared a compost system would ruin the local environment they were elected to protect. They delayed the permits, required a monitoring program, and insisted that Fairview comply with ADA access requirements, even though the farm itself is not really accessible to disabled persons.

The entire cost of the project, which included the permitting, architect, building, the toilet, and two shower stalls for employees, came to about $75,000, including $8,000 for the composting toilet system. “But it probably would have cost us twice or three times as much to put in a traditional system, due to the costs of making the sewer connection,” says Logan.

More typical is the relatively extensive installation of composting toilets at Ski Apache ski area in New Mexico. The area’s base lodge composting toilet system, including 12 toilets, cost $27,000. “If you just went to put in a septic, it would be $10,000 to $12,000 just for that. But then you have the rest of the expense. So it’s nearly a wash,” says maintenance supervisor Rick Hall. Overall, Ski Apache has found that composting systems require less maintenance and are subject to fewer problems (no clogged johns or frozen pipes). Hall describes them as labor- and money-saving in the long run, as well as environmentally superior.

“There’s nothing about a horse farm that would make an installation difficult,” adds Mills. “We’ve installed more than 10,000 systems, many into homes, public parks, and office buildings. If anything, it should be easier to install and maintain in an agricultural environment.”

Composting toilets do place limits on building design. There must be space for the tanks below the bathroom units, with room for maintenance personnel to service the tanks. So restroom buildings require a basement or two stories, and this can also add to the cost. At Fairview, the initial plan was for a two-story building, but wheelchair access required a ground-level bathroom, so the holding tank is in the basement. But given the many advantages over traditional systems, composting toilets often come out smelling like a rose.