Short abstract:

The water authority in Paris suburbs, SEDIF, has promoted reverse osmosis (RO) to eliminate micropollutants. Consequently, the National Commission for Public Debate organized public hearings on water quality, not RO. Water quality has become a local political topic despite the regulatory framework.

Long abstract:

European norms specify tap water quality. They are produced by the scientific knowledge of health and environment agencies and political negotiations between EU institutions. Heads of water public services are responsible for tap water quality. The water authority in Paris suburbs, SEDIF, has promoted reverse osmosis (RO) technology to create a “pure water, devoid of limestone and chlorine”. SEDIF argued that RO eliminates all micropollutants and limestone during the treatment process. It also argued that RO means avoiding injections of chlorine into the water network. A local water authority poised as the authority defining water quality : this reformulated the definition of drinking water quality. Given the large scale of this project, NGOs applied to the National Commission for Public Debate to organize a participatory debate on this project. The independent body chose to focus the debate, which occurred from April to July 2023, on water quality instead of RO. Water quality became a local and publicly debated issue (and not only an issue for experts): this was the second step in reformulating the definition of drinking water quality. In this process, the public debate became a hybrid forum where technological innovations were questioned by lay persons. The public debate embodied a socio-technical controversy: this was the third step of the reformulation process. Water quality and the ways to achieve it were thus politicized as bearing ideological orientations.