Composting Toilets: Is a Waterless Composting Toilet for You?

Enlarge Image Image Gallery Composting toilets require little to no water. Toilets account for about a quarter of a typical home's water use. Photo Courtesy Biolet

It used to be that people who owned composting toilets lived off the grid in hippie compounds or in underdeveloped countries. The toilets—which don’t require water or sewage systems—also were used for isolated summer camps, poolsides, boats and cottages. Today, composting toilets are a fast-growing trend in green building; you can even buy one at Home Depot or Ace Hardware. In Austin, Texas, composting toilets have been approved for household use (though the city must approve each site). A recently constructed 30,000-square-foot office complex at the University of British Columbia was equipped with composting toilets so the building did not need to be connected to the sewer system.

What is a composting toilet?

Composting toilets are well-ventilated containers in which human waste can decompose under controlled aerobic conditions, according to the Environmental Protection Agency (EPA). Natural bacteria and fungi—and in some cases peat moss, sawdust or other organic matter—break down waste and toilet paper into humus, a fully decomposed, odorless waste that is 10 to 30 percent of its original volume.

In self-contained units (the most common type), compost decomposes in a chamber attached to the toilet. More complex “remote” or “central” units move waste to a composter in another location (such as the basement or outdoors) to decompose. Regardless of the type of composting toilet you choose, fully decomposed humus must be removed and disposed of once fully processed. Fully decomposed humus poses little risk to handlers and, depending on local laws, owners can remove bins of decomposed humus themselves and bury it as a soil amendment or have a septic hauler remove it.   

Advances in composting toilets mean they require less homeowner maintenance. Some composting toilets use minimal electricity or battery power, which can come from solar power, to fully automate all or nearly all steps required for decomposition. Composting toilets with multiple composting bins eliminate exposure to unprocessed composting waste. While one bin receives waste, a separate bin processes waste. Such systems can easily accommodate an entire family.

Choose your loo 

Multichamber batch systems 
Centralized, or multichamber batch systems, require less maintenance. They include two or more excrement bins; while one is in daily use, the other composts.

Pros: Each batch is able to cure fully without adding new excrement; these systems don’t require as much oversight as self-contained systems.