Composting toilets: Do they pass the sniff test?

By Betsy Herbert

Santa Cruz Sentinel

Posted: 08/15/13, 12:00 AM PDT

With water-conservation ideas generating so much buzz lately, it's worth revisiting an old technology -- the composting toilet -- to see if it might offer new solutions.

Composting toilets have been around for decades, they use little or no water, and they treat toilet wastes on-site for re-use as valuable compost. How have these devices, with their enormous nationwide water-saving potential, fared recently in public acceptance and use by the building sector for residential, public, and commercial spaces?

Significant advances in composting toilet technologies have overcome many of the composting toilet's initial problems like odor and certain waste-disposal issues. Still, the newly designed and odor-free composting toilets are a hard sell to the general public, which largely still views them as "classy outhouses," says Peter Scott, a retired professor of physics a UC Santa Cruz, who has written about composting toilets.

The good news is that the latest composting toilets now pass the sniff test. Many models have been tested, approved and listed by the National Sanitation Foundation. The LEED rating system lists composting toilets as one way to reduce a building's water consumption, along with electronic controls, waterless urinals and water-efficient fixtures. According to architect Ed Lebard at, the Chesapeake Bay Foundation headquarters, built in 2000 in Annapolis, Md., became the nation's first LEED Platinum building to use composting toilets. Its toilets use negative pressure (vacuum) to suck the air away from the resulting waste. The waste is then fertilized with chip wood, processed through compost in a tank, then re-introduced into the soil near the building.

Other major public installations of composting toilets include Oakes Hall at the Vermont Law School in South Royalton, Vt., and the Bronx Zoo in New York.

Composting toilets are featured in a house designed by a Portland architecture firm Departure. The homeowner's goal is net-zero water usage. Other water-saving features include an 11,000-gallon potable water cistern underneath the carport, stormwater catchment and complete grey water processing.

In California, both Yosemite National Park and the Presidio in San Francisco have installed public restroom facilities that use composting toilets. At the Presidio, composting toilets were found to be cost-effective, compared to extending the sewer line, and because of their sustainability features.

Locally, composting toilets are not exactly a hot item. Julia Bettencourt, co-owner of Plumbed Elegance in Santa Cruz, says her retail store doesn't offer composting toilets because, "no customer has ever requested one and no plumbing fixture rep has ever walked in the door to show me a line of composting toilets. There seems to be no market for them."

"Yet," Bettencourt said, "every two or three days someone calls asking for a toilet seat to fit their old 5-gallon flush toilet. So there's a lot of those still out there. One of those old toilets can use 30,000 gallons per year."

According to Toby Goddard, city of Santa Cruz water-conservation manager, "Composting toilets require periodic maintenance and management of decomposed matter." So, he says both the 2010 California Plumbing Code and Santa Cruz Municipal Code currently prohibit their use, "except in limited-density, owner-built, rural dwellings, and where approved by the local health official."

John Ricker, Santa Cruz County water resources director, said the county conducted experimental installations in the San Lorenzo Valley in the 1980s: "All the composting toilets failed at different sites for different reasons."

Recognizing recent advances in composting toilet technology, however, he said the county is "considering installing one at the future Felton library."

Ricker said, "The county cautiously considers experimental installations as long as they have some sort of conventional backup facility."