For the first time since 1923, the River Seine is open to public swimming. Paris authorities lifted the century-old ban on July 5, 2025, following a multi-year cleanup operation that cost €1.4 billion. The river, long considered off-limits due to sewage overflow and bacterial contamination, now hosts three designated swimming zones near Notre-Dame Cathedral, the Eiffel Tower, and eastern Paris. The move follows its use in the 2024 Olympics, where open-water events were held in the Seine under strict water quality monitoring.
The city installed disinfection units, expanded sewer connections, and built a massive rainwater retention basin to prevent untreated runoff from spilling into the river during storms. Houseboats were forced to connect to municipal sewage systems. Homes upstream were rerouted from rainwater drains to treatment plants. These infrastructure changes were designed to meet European water safety standards and were tested daily in the lead-up to the Olympics. Since early June, water quality has remained within acceptable thresholds, with only two exceptions caused by heavy rainfall and boat discharge.
Swimming is permitted only within the three official zones. Each site includes lifeguards, changing rooms, showers, and beach-style furniture. Access is free until August 31. Flags are posted daily to indicate water safety. Green means go. Red means stay out. The average depth is 3.5 meters. Currents remain strong. Boat traffic is active. Lifeguards assess swimming ability before allowing entry.
Sources:
https://ca.news.yahoo.com/parisians-historic-plunge-river-seine-142031444.html
https://www.dw.com/en/paris-reopens-seine-river-for-public-swimming/a-73163816