How a composting toilet works


Composting involves the biological decomposition of organic matter using natural occurring organisms such as bacteria, fungi and other small organisms into compost which is a humuslike product. The composting process can be aerobic or anaerobic however aerobic decomposition is desirable because it is efficient and does not produce unpleasant odours.

Composting in a EcoLet is effectively aerobic however there may be anaerobic decomposition within small pockets within the compost pile. The composting process involves four main components: microbes ( including bacteria, fungi and protozoa), organic matter, water and oxygen. The carbon compounds present in the organic materials are used by the microorganisms as an energy source and transformed into carbon dioxide using the oxygen present.

As the carbon dioxide and water vapor is released into the environment the pile becomes smaller. Nitrogen is also a crucial element in the composting process which is required by the microbes for cell growth. For optimal decomposition the ratio of carbon to Nitrogen should be around 30:1. Urine and human feces are relatively high in Nitrogen and therefore additional carbon is required for optimal composting.


Moisture In optimum conditions, the compost material has the consistency of potting mix about 35% to 65% moisture. When below 35%, there is not sufficient moisture for the microorganisms to function and above 70% saturated conditions begin to develop and oxygen depletion becomes a limiting factor.

Under these condition the process becomes anaerobic and the process releases odorous gases such as methane and hydrogen sulfide.


The optimum temperature range for most compost toilets is 18°C to 45°C. Lower temperatures result in a mouldering process that takes a significantly longer period of time to compost. Additional chambers may be required in this instance.


The aerobic organisms responsible for the composting process require air to survive. Without air, they will die and be replaced by anaerobic micro organisms that will slow the composting process and generate odour.

For compost toilets to work most effectively, the material being composted should be unsaturated with liquids, and have a loose texture to allow air to circulate freely within the pile.


Pathogens are eliminated through the long retention times in the compost, the compost temperature and the activity of the micro-organisms


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