Swim­ming in the Seine

Absti­nence

Swim­ming in the Seine had been banned since 1923. Pollu­tion from indus­trial waste­water and inade­quate sewage systems had turned the water of Fran­ce’s most famous river into a health hazard. Swim­ming in the Seine seemed to be lost forever.

The 2024 Olympic Games in Paris have changed a lot, here they became the cata­lyst for a historic turn­around. The Seine was exten­si­vely reno­vated with invest­ments of 1.28 billion euros. New sewage treat­ment plants, state-of-the-art waste­water systems and inno­va­tive puri­fi­ca­tion tech­no­lo­gies were intended to bring the river back to life. However, despite these enormous efforts, water quality remained a critical issue during the Games (and remains so to this day): Heavy rain­fall repea­tedly led to elevated bacteria levels that jeopar­dized indi­vi­dual compe­ti­tions.

A signi­fi­cant post-Olympic legacy is ther­e­fore the inau­gu­ra­tion of the bathing area in Grenelle (15th arron­dis­se­ment) on July 5, 2025 as a symbol of the return of the Seine as a living and usable part of ever­yday life in Paris.

The design was created by Mater Studio.

Tech­no­logy

The chal­lenges posed by the “Baignade en Seine de Grenelle” project were quite considerable, as it involved the cons­truc­tion of a comple­tely demoun­table floa­ting bathing faci­lity for 300 people, which had to adapt to the constantly chan­ging water levels of the Seine. The result is a 950 m², 60 meter long swim­ming area with a 415 m² floa­ting plat­form and 480 m² of land faci­li­ties.

The main corner­stones of the design are:

• Mobile cons­truc­tion: The entire system glides on vertical rails that are anchored to the quay with invi­sible concrete blocks.
• Adap­tive access: Two 25-meter-long swivel foot­bridges conti­nuously adjust to the water level and ensure barrier-free access.
• Stabi­lity: The struc­ture can be used by 300 people without risk of defor­ma­tion.
• Emer­gency prepared­ness: If there is a risk of floo­ding, the entire system can be dismantled within 48 hours.

Design

Despite the tech­nical comple­xity, the design intent is clearly reco­gnizable. The yellow railings and metal­work were inspired by the Art Deco forms of the 1920s – the era in which Paris cele­brated its first public swim­ming pools as archi­tec­tural master­pieces. The yellow and blue color scheme deli­bera­tely evokes leisure, vaca­tions and summer.

The inte­gra­tion into the surroun­dings is also successful: although located at the foot of the Eiffel Tower, the Grenelle bathing area, discreetly nestled under plane trees and lime trees, does not compete with the histo­rical back­drop, but creates a new perspec­tive from the river.

The use of mate­rials and cons­truc­tion methods is also successful:

• Reuse: The ship­ping contai­ners used have already circum­na­vi­gated the world several times.
• Natural mate­rials: Robinia wood, the only Euro­pean hard­wood that is natu­rally resistant to mois­ture without chemical treat­ment.
• Modular design: Like a giant Meccano system, the numbered precision cons­truc­tion enables quick assembly and disas­sembly.

Rain

The Grenelle bathing area is one of three free bathing areas that have been available to Pari­sians again since the summer of 2025.

Life­guards monitor the bathing areas and carry out regular safety checks. The problem remains the water quality of the Seine, and this is “variable” because it is very depen­dent on the weather. Heavy rain­fall causes sewage and surface runoff to enter the river, which increases bacte­rial levels. Ther­e­fore, daily checks are carried out and swim­ming can be suspended when it rains, which does happen.

Overall, despite these problems, the Grenelle bathing area is a very good example of how cities can reclaim their natural resources and shape them for the future, also with regard to climate change.