Environmental Benefits

The environmental benefits of using a composting toilet are astounding.

– Firstly, you are working to help protect ground water and surrounding lakes from excessive nutrients and polluting pathogens.

– Secondly, with every non-flush, you are literally saving litres of water.

Human waste is 90% water. And in regular toilets, all 90% of that polluted liquid ends up in our groundwater, lakes or rivers. The excessive nutrients and pathogens this wastewater contains lead to a build up of potassium and nitrogen in lakes, both of which foster weed growth and blue-green algae development. Such growth absorbs the dissolved oxygen in the lake and eventually works to kill it. More local councils are refusing to allow the installation of septic systems due to the impact they have on the local environment even up to 50m away. Contaminated oysters are just one example of this effect.


Sun-Mar composting toilet systems evaporate excess liquid (up to eight litres per day) and diffuse it into the atmosphere, meaning no contaminated polluted water is released unnecessarily into our water supplies. Whatever liquid that is not evaporated flows through an outlet drain into a small L 2m x  W 0.4m x  H 0.4m absorption trench. This may be only 1.5L per person per day compared with a septic system which can allow seepage of up to 125L per person per day (sewerage mixed with all other grey water).

Water is a precious and finite resource. In many parts of the world, it is already becoming scarce. The idea of flushing perfectly reasonable drinking water down the toilet is thus becoming unthinkable.

Most Sun-Mar composting toilets require no water at all and therefore save a huge amount of water each and every use.

A four-person household using a regular toilet will flush around 95 litres of water down the toilet each day. That is about 35,000 litres per year PER HOUSEHOLD.

Waste is essentially a compilation of fluid and complex organic molecules. The vast majority of these contain carbon and hydrogen atoms. The benefit of a composting toilet is that aerobic bacteria work to break down these molecules into usable elements like water and carbon dioxide. Both of these are dissolved into the atmosphere, along with the residual moisture that is evaporated.

What remains of the waste is essentially oxidized salts. This accounts for about 3% of the original waste mass. These salts are collected in the finishing drawer and well suited to nourishing plants.

A composting toilet, therefore, works to re-introduce the nutrients taken from the earth back to the plants that they came from. A permaculturalist’s dream toilet!