Composting toilets are used in homes where there's little or no water supply, or where the homeowner wants to limit water use. They are self-contained units not connected to a sewer or septic system. They store human waste inside, where it breaks down into a compost that can be added to lawn or around trees. Many jurisdictions regulate residential use of composting toilets. In the U.S., National Sanitation Foundation Standard 41 is applied. Some, but not all, models have been tested for compliance.
Control of Disease
Since exposed human waste can be a major vector for disease, composting toilet regulations usually require that a composting toilet be inaccessible to insects and rodents. According to Living Outside the Box, many laws require that the toilet be animal-proof. The owner may be required to install screens in all openings to the composting chamber, if they are not already present.
Composting toilets should be made out of durable materials that will not decompose with the waste. Regulations may require that the toilet be constructed from manufactured materials that have a documented resistance to bacteria and decay.
Human waste poses a hazard to clean water. A poorly built composting toilet could contaminate drinking water supplies, spreading nitrogen and disease-causing organisms. Most regulations require that all waste remain contained in the toilet until it is fully decomposed. Any waste that leaves the toilet before composting is complete may have to be disposed of in an approved manner, using a septic system or sewer.
Periodically, composted waste must be removed from the toilet. If the composting toilet is functioning correctly, its product is harmless, contains no pathogens and lacks an unpleasant smell. However, local regulations usually restrict the use of the compost produced from a toilet, due to the risk of incomplete composting. According to Inspectapedia, the waste may be placed around flowers, shrubs and trees in most locations. However, compost from human waste is rarely allowable for use in vegetable gardens or other food-producing plants. Some jurisdictions require that the waste be disposed of in a sewer or septic system even if it is fully composted.
As composting toilets must contain waste until it has broken down completely, they require a storage area. Most areas require homeowners to buy or build a composting toilet that is sized appropriately for the number of people in the home and the frequency of use. If a commercial toilet with a documented rating is not purchased, the homeowner may need to document the capacity of the toilet before it can be approved.