Overview

• The reopening marks completion of a €1.4 billion, Olympic-driven cleanup that upgraded disinfection units, storage basins and sewer systems along the Seine.
• Three free swimming zones—at Notre Dame, the Eiffel Tower and in eastern Paris—are open through August with scheduled sessions for swimmers aged 10 or 14 and older.
• Paris authorities conduct daily water sampling and display green or red flags under European criteria to regulate access and maintain lifeguard oversight.
• Houseboats and upstream homes have been rerouted to municipal sewers and new treatment plants to prevent direct sewage discharge into the river.
• Independent tests reveal variable bacterial undercounts and past athlete illnesses have heightened lingering concerns over water quality despite regulatory compliance.