Bugey Sud. Bacteriological contamination of water: the causes are still being investigated.

Restrictions on tap water consumption have been lifted, but questions remain. Since September 6, residents of Parves-et-Nattages, Cressin-Rochefort, Lavours, Massignieu-de-Rives, and Vongnes have been able to resume normal water use after a bacteriological pollution alert was issued on August 28. But what is the origin of the concentration of coliform bacteria—including Escheria coli—and enterococci repeatedly present in the water supply? Where does the problem lie in relation to the groundwater captured in Cressin-Rochefort?

Taking the situation very seriously, SAUR, the public service provider in this sector, and the Bugey Sud Water Authority have not yet been able to identify all the causes of this episode. SAUR cites "a combination of factors that have led to a gradual deterioration in the quality of the water resource, notably an increased concentration of iron and manganese." Among the factors cited are the high temperatures of the two heatwaves. "This phenomenon [...] alters the effectiveness of the chlorine used to disinfect the water, reducing its ability to eliminate bacteria," says SAUR. "Furthermore, the further the distribution point is from the treatment plant, the longer the water remains in the pipes. This delay promotes the degradation of chlorine, which can compromise the microbiological quality of the water. This is what was observed in late August, during a sample taken from a tap in a school after two months of school holidays." » The fact remains that previous heatwave episodes have not caused this situation.

"Hydrogeologists are currently being mobilized to analyze the causes of this degradation and additional studies are underway to better understand the phenomena at play and identify sustainable solutions," says the company, which notes that "climate change has a direct and increasing impact on water quality."