Aspects socio-économiques de la demande en eau potable

Abstract

This paper presents socio-economical data on drinking water demand with two objectives : a) trying to explain current trend of water demand decrease, and b) to provide guidelines for an efficient policy in drinking water resources management. Water demand decrease has started in France around 1990 and represents between 0,5 % and 1 % per year until present (apart some influence of the climate like 2003 canicle). It is probably a long term adjustment between water demand and water tariff which has increased in average from 2 to 3 euros/M3 in the 90's, and also from a widespread use of individual metering in France. This process is quite slow, because of relatively expensive systems that the consumer needs to implement to decrease his water demand (water efficient devices at home, and in some cases self production of water by means of individual wells, rainfall collection systems, or separated irrigation systems). The better efficiency in domestic water use is partly balanced with inefficient effects. The competition between individual water systems and public water service will result in global increase of water cost. Public awareness of water scarcity is very high since drought of 2003. However reducing water consumption has very little impact on the environment compared to other actions like improved wastewater collection and treatment, renewable energy source for water warming, or replacing water resources with negative effects on aquatic habitats by other water resources. For an efficient water resources policy, it is necessary to balance correctly individual efforts expected from consumers and collective efforts like a) more efficient water network management (leakage detection), b) new or replacement water resources when necessary. Collective actions appear to be generally more cost effective.