Recycling grey water

Principle

 Grey water is soapy wastewater from sinks, washbasins, showers, baths, dishwashers and laundry washing machines. This wastewater can be recovered and reused by tourist establishments for various purposes, to reduce overall water consumption.

Explanations

This type of wastewater can be reused as water to flush toilets, and/or to water plants and green areas, according to the Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (Anses,France).

Implementation

It is difficult to install a grey water recycling system in the course of renovation work. These systems are more readily installed in new construction.

Grey water must be cleaned to remove potentially dangerous products and contaminants. A double water supply system must be installed, one for potable water from the public water supply, and another closed-loop circuit for grey water which is filtered and recirculated for household uses.

If the grey water supply is insufficient, the circuit is topped up with potable water.

A grey water recycling system can be installed by a specialised contractor, or created by an experienced handyman.

Costs

Between €6 000 and €7 000 for a domestic system.

Benefits

Grey water typically represents about 40% of water consumption. Reusing this wastewater would considerably reduce total water consumption.

Constraints

Difficult to install in existing buildings.