Overview

• The three designated Seine swim zones at Grenelle, Île Saint-Louis and Bercy remain shuttered after rain-triggered red-flag warnings on July 6.
• Daily real-time sensor monitoring and lab analyses will determine when water safety returns to acceptable standards.
• Their July 5 opening marked the first public swimming in the Seine since 1923, enabled by a €1.4 billion sewage and stormwater treatment upgrade.
• Swimmers must be at least 14 years old, prove swimming ability, meet height requirements and wear a safety buoy but enjoy free access in authorized areas.
• Independent experts warn that bacterial concentrations in the river can spike unpredictably, raising doubts about the consistency of official safety assessments.