Non-collective sanitation: management techniques

A home's wastewater drainage system is essential to its healthy, long-lasting operation. Non-collective sanitation (NCS) refers to individual installations for the treatment of domestic wastewater. These systems concern detached houses with up to 20 rooms that are not served by a public wastewater collection network, and which must treat their own wastewater before discharging it into the natural environment.

Wastewater with a low pollutant load comes exclusively from kitchens and bathrooms, i.e. from sinks, washbasins, showers and bathtubs, not forgetting dishwashers, washing machines and tumble dryers (this is grey water).

Black water (BW) comes exclusively from toilets; it's also known as "black water".

Wastewater treatment plants must be able to treat all of this wastewater and EV containing potentially pathogenic micro-organisms, organic matter, nitrogen, phosphorus or suspended matter; polluted wastewater can be the source of significant environmental nuisance and health risks.

After collection, domestic wastewater is pre-treated in a watertight tank, which allows suspended solids in the collected water to settle out, floating elements to be retained and a first stage of degradation to take place.

The wastewater is then sent to the treatment plant, where pollution is eliminated by biochemical degradation (microbiological activity) of the water as it passes through a natural reactor consisting of either natural soil or reconstituted soil.