Drinking water - Treatment process lines and effects of the climate change

Depending on the availability and quality of resources, raw water for drinking water production is drawn from groundwater or surface water (rivers, canals, natural or reservoir lakes, etc.). Although 95% of the resources used are of underground origin, they account for only two-thirds of the volumes tapped. Surface water accounts for the remainder of resources, but only one third of volumes tapped.

Modern regulations in France and Europe on water intended for human consumption (excluding natural mineral water) are historically based on the EU Directive of July 1980, translated into French law by Decree 89-3 (and other national publications). This was followed by Decree no. 2003-461 of May 21, 2003 on certain regulatory provisions of the Public Health Code (based on the EU Directive of December 1998) and, more recently, EU Directive no. 2020/2184 of December 16, 2020, accompanied by orders, decrees, information notes, etc., leading to its transposition into French law in 2022 .

These regulations define water intended for human consumption as follows:

• do not contain a number or concentration of microorganisms, parasites or any other substances constituting a potential danger to human health;

• comply with a certain number of quality limits and references set (see "to find out more") by Directive 2020/2184 and its transposition into French law [W 1 700] .

In the 1960s-1970s, groundwater was simply pumped, chlorinated and distributed. All surface water treatment systems were designed according to the classic "coagulation, flocculation, settling, deep filtration, disinfection" scheme, with almost systematic pre-chlorination, enabling the various processes to work in a chlorinated environment without any biological phenomena taking place.

The considerable development of knowledge in analytical chemistry and toxicology, the publication of new regulations and consumer demands all help to explain why treatment processes, including those based on groundwater,...