Composting Toilets Offer Solution to Water, Sanitation Problems

composting toilet
Composting toilets like this Envirolet model may help address the global water crisis.

Predictions of more-severe droughts and worsening water shortages as the Earth’s climate changes have led to an increased interest in composting toilets. These toilets, once deemed just for “hippies” or for areas without access to municipal sanitation, have evolved into sophisticated machines that many now prefer to conventional toilets. In addition to potentially saving the planet billions of liters of water a day through no-flush or extremely low-flush systems, composting toilets can provide nutrient-rich compost and even fertilizer for crops and other vegetation.

According to the advocacy group Composting Toilet World, the basic practice of composting human waste has been used in China for centuries, and it is still prevalent in some rural areas today. Historical as well as modern composting toilets function much like conventional flush toilets, but they use little or no water. Instead of sending waste into the municipal waste stream, composting toilets store it in an on-site compartment to facilitate natural aerobic decomposition, eventually producing a nutrient-rich compost. When used properly, the systems are odorless and kill any waste-borne pathogens. Some systems separate liquid from solid waste to create a liquid fertilizer in addition to the compost. Toilet designs range from the relatively simple, do-it-yourself bucket or bin systems featured in The Humanure Handbook, to hi-tech patented systems like Biolet, Envirolet, and Sun-Mar.

Typical “low-flush” toilets in the United States and Canada use 6 liters (1.6 gallons) of water per flush, notes Scott Smith, vice president of Canada-based Sancor Industries, which manufactures Envirolet Composting Toilet Systems. Thus, by switching to a no-flush composting toilet, a person can save more than 8,000 liters (2,000 gallons) of water per year, assuming an average flush rate of four times daily. “In 25, 50, 100 years, we probably won’t have the luxury of using clean water to wash away waste,” Smith observes.

For many parts of the world, flushing with clean water (often water that has been purified to drinking quality standards) has never been an option. According to the World Health Organization, as many as 1.1 billion people, almost all in the developing world, still do not have access to safe water, and some 2.6 billion people—about 4 in 10—lack access to basic sanitation. Every year, 1.6 million people die from diarrhoeal diseases spread by unsafe drinking water and poor sanitation.

Scott Smith of Sancor Industries notes that his company will be offering lower-cost composting toilets starting in 2007 in hopes of serving the developing country market. According to Smith, it is important to promote the systems in both developed and developing nations. While the compost resource the toilets provide can be beneficial to people across the globe, the real issue is saving water, he explains: “Composting toilets are a solution to the water crisis that is coming.”


This story was produced by Eye on Earth, a joint project of the Worldwatch Institute and the blue moon fund. View the complete archive of Eye on Earth stories, or contact Staff Writer Alana Herro at aherro [AT] worldwatch [DOT] org with your questions, comments, and story ideas.