A composting toilet is a toilet that receives non-water-carried wastes, such as human excreta, urine, and some organic kitchen wastes, and transmits it to a composting chamber. The waste undergoes drying and varying degrees of decomposition.

The toilet can contain mechanical agitators, thermostats, humidistats, heaters, and fans to ensure that proper moisture content and temperatures are maintained. Direct homeowner involvement is required to monitor moisture and temperature levels. The key maintenance activity is periodic removal of the composted waste.