Reducing the cost of production of potable water is one key challenge for the local decision-makers of French cities. In fact, according to the manager of potable water in Paris region (Syndicat des Eaux d’Ile-de-France) the average cost of production and transport (until arriving to the users) of potable water in 2015 is 2.50 euros per m3. It represents about 70% of the total cost of each m3 of potable water in the majority French great cities.
Furthermore, as stated by the Water Information Center (centre d’information sur l’eau) the average domestic water consumption in France is 137 litres per day and per inhabitant, with 9.50 litres (7%) devoted for alimentary consumption (drink and food preparation). Only, therefore, this quantity requires really the potable quality, while the rest can be satisfied by a less quality than potable one, specially: the outside consumption (watering, car cleaning), house cleaning (watching machine, dish machine) and toilets fleshing that represent 74 litres (54%).