Seine Bathing-Water Sensing & Public Swimming Return
This overview was generated with AI from the public sources listed below and checked against them before publication. It has not had a complete human fact-check — treat it as a starting point and follow the sources.
How this atlas is made · What “last verified” means · What “source-checked” means · The full record behind this page
✎ Corrected 27 Aug 2026 Publication date recorded for 5 sources. What changed →
Paris reopened the Seine to public swimming in the summer of 2025, the first legal bathing in the river in central Paris after a ban lasting more than a century. Three supervised pools are built into the river — in 2026 at the bras Marie, at Grenelle and at Bercy, open from 4 July to 30 August, free to enter — and each of them opens or closes on the day's water quality. Samples are taken from the river every day and analysed in a laboratory for Escherichia coli and enterococci against the thresholds recommended by the regional health authority under the European bathing-water directive; automated real-time measurement, field observation at and around the sites and hydro-meteorological tracking sit around that laboratory result.
what does this mean?
The strongest source is the operator's or the city's own reporting — an official report, dataset or press release. It grades who did the looking — not how well the project went. All four grades →📊 Impact
Across July and August 2025, the first season, the three Paris sites were open on about two thirds of the days and drew close to 100,000 swimmers, in weather the city itself calls unfavourable for July. Île-de-France ran seven permanent bathing sites on the Seine and the Marne that year and eight in 2026.
🎓 Lesson
The sensors are the alarm; the laboratory is the decision. Paris's own account of the daily check puts samples analysed in a laboratory first, and adds the real-time automated device, the field observations and the weather watch around it — and the results posted at the entrance to each site are the health authority's own regulatory sampling, run in parallel with the city's. What that machinery buys is not a clean river but a decision every morning, and a third of the mornings it went the other way. The water quality itself was not bought with sensors: sewer works under the bathing plan launched in 2016 — network upgrades, connecting the Paris river ports and the boats moored there to the sewer, wet-weather storage basins and the correction of wrong connections — came to a total commitment of close to €1.3 billion.
Sources
Show your work What this page rests on and what it can’t tell you · all 8 claims with their sources · the forensic record
Evidence Passport · public beta 8 addressable claims, 5 source dossiers, one permanent baseline. The passport is unreviewed — an AI-assisted structural migration, not a human or expert endorsement. Every revision keeps a permanent copy under revision history.
Inspect the claims, one by one — verbatim text, sources and caveats for all 8
The text below is copied verbatim from the published record. Each claim names the source dossiers that carry it; caveats stay attached to the claim they qualify.
clm-1ba7a30a0268a540
quantitative
Paris reopened the Seine to public swimming in the summer of 2025, the first legal bathing in the river in central Paris after a ban lasting more than a century
Sources carrying this claim
clm-587845a3ba4c4982
quantitative
in 2026 at the bras Marie, at Grenelle and at Bercy, open from 4 July to 30 August, free to enter
Sources carrying this claim
clm-9436e9e56f9f4d9c
descriptive
Samples are taken from the river every day and analysed in a laboratory for Escherichia coli and enterococci against the thresholds recommended by the regional health authority under the European bathing-water directive
Sources carrying this claim
clm-ecb6759ecac3869f
descriptive
automated real-time measurement, field observation at and around the sites and hydro-meteorological tracking sit around that laboratory result
Sources carrying this claim
clm-fd0ca1cc69bc5ff8
quantitative
Across July and August 2025, the first season, the three Paris sites were open on about two thirds of the days and drew close to 100,000 swimmers, in weather the city itself calls unfavourable for July
Sources carrying this claim
clm-37751bd1ec576027
quantitative
Île-de-France ran seven permanent bathing sites on the Seine and the Marne that year and eight in 2026
Sources carrying this claim
clm-529c122ffc942213
descriptive
the results posted at the entrance to each site are the health authority's own regulatory sampling, run in parallel with the city's
Sources carrying this claim
clm-0b601da93bdaadd0
quantitative
sewer works under the bathing plan launched in 2016 — network upgrades, connecting the Paris river ports and the boats moored there to the sewer, wet-weather storage basins and the correction of wrong connections — came to a total commitment of close to €1.3 billion
Sources carrying this claim
Forensic record — source dossiers, gaps, hashes and the exact revision this page renders
This layer records what is known about each source, what is still missing, and the exact snapshot this page is rendering. A missing date, archive or hash stays visible as missing.
Awaiting operator and domain-expert review; publication of this revision implies neither.
sha256:fdb28ab8c9369df2ef1d51e45dd7312dcbf98f72ac59302b33f9959239156dd9
- 8
- of 8 claims mapped
- 5
- source dossiers
- 1
- publication dates recorded
- 0
- archives linked
- 0
- exact locators
- 0
- content captures hashed
Governance facts carried by the record
- Operator
- Ville de Paris
- Actor types
- city-government
- Funding model
- public
- Funding description
- Not recorded
- Cost
- Not recorded
- Ownership
- Not recorded
- Decision rights
- Not recorded
- Exit conditions
- Not recorded
5 source dossiers
Ville de Paris — Baignade dans la Seine: what to know before swimming this summer (authority)
- Stable source ID
src-a3c45512fa30db51- Publisher
- Name not classified · paris.fr
- Type / language
- web-page · language not classified
- Published
- Not recorded
- Updated
- Not recorded
- Source last checked
- No source-level check date
- Record last verified
- 2026-08-27
- Dossier created
- 2026-08-27
- Retrieved copy
- No local capture recorded
- Archive
- No archived copy linked
- Content hash
- No captured content hash
- Locator
- Descriptive only — not page/paragraph exact
Open the recorded source note
Official dossier: sites, daily testing, upstream sensors, ARS oversight, flag system. The page states no publication date.
- Claims linked
Fluidion — Monitoring the Seine River in Paris (vendor case study)
- Stable source ID
src-e0bc97eb4cb19b3e- Publisher
- Name not classified · fluidion.com
- Type / language
- web-page · language not classified
- Published
- Not recorded
- Updated
- Not recorded
- Source last checked
- No source-level check date
- Record last verified
- 2026-08-27
- Dossier created
- 2026-08-27
- Retrieved copy
- No local capture recorded
- Archive
- No archived copy linked
- Content hash
- No captured content hash
- Locator
- Descriptive only — not page/paragraph exact
Open the recorded source note
In-situ automated ALERT E. coli/enterococci sensors and Seine open-data initiative. The page states no publication date.
- Claims linked
- Background source; no baseline claim points here
Al Jazeera — River Seine reopens to Paris swimmers after Olympics and a century-long ban (5 July 2025)
- Stable source ID
src-60c4d47654d66bd2- Publisher
- Name not classified · aljazeera.com
- Type / language
- web-page · language not classified
- Published
- 2025-07-05
- Updated
- Not recorded
- Source last checked
- No source-level check date
- Record last verified
- 2026-08-27
- Dossier created
- 2026-08-27
- Retrieved copy
- No local capture recorded
- Archive
- No archived copy linked
- Content hash
- No captured content hash
- Locator
- Descriptive only — not page/paragraph exact
Open the recorded source note
Reopening after century-long ban; ~€1.4bn cleanup investment; daily sensor + sample testing.
- Claims linked
Ville de Paris — how the water quality of the Seine is analysed, with the published bulletins (authority)
- Stable source ID
src-de8d9452cfbaa8a8- Publisher
- Name not classified · paris.fr
- Type / language
- web-page · language not classified
- Published
- Not recorded
- Updated
- 2026-08-19
- Source last checked
- No source-level check date
- Record last verified
- 2026-08-27
- Dossier created
- 2026-08-27
- Retrieved copy
- No local capture recorded
- Archive
- No archived copy linked
- Content hash
- No captured content hash
- Locator
- Descriptive only — not page/paragraph exact
Open the recorded source note
Daily sampling analysed in a laboratory for Escherichia coli and enterococci against the regional health authority's thresholds under the European bathing-water directive; the health authority's own parallel regulatory sampling is what is displayed at each site entrance; real-time automated measurement, field observation and hydro-meteorological tracking alongside; the published water-quality bulletins.
Ville de Paris press office — eight bathing sites for the 2026 season, with the review of the 2025 season (authority)
- Stable source ID
src-dbe3b29e6c3eb67d- Publisher
- Name not classified · presse.paris.fr
- Type / language
- web-page · language not classified
- Published
- Not recorded
- Updated
- 2026-06-05
- Source last checked
- No source-level check date
- Record last verified
- 2026-08-27
- Dossier created
- 2026-08-27
- Retrieved copy
- No local capture recorded
- Archive
- No archived copy linked
- Content hash
- No captured content hash
- Locator
- Descriptive only — not page/paragraph exact
Open the recorded source note
Review of the 2025 season: the three Paris sites open on average two thirds of the days in July and August, close to 100,000 bathers, unfavourable July weather; seven permanent bathing sites on the Seine and Marne in 2025 and eight in 2026; sewer works under the bathing plan launched in 2016 totalling close to €1.3 billion.
Known limits of this passport
- Publisher names and source languages have not yet been classified; domains are recorded without guessing.
- Existing source notes are descriptive locators, not page- or paragraph-exact citations.
- A missing archive, publication date or content hash is shown as null rather than inferred.
- The project-level evidence grade ranks the strongest source in the entry; it is not a truth score for every claim.
Continue exploring
Compare this project
May you swim? Three cities, three answers from the same kind of sensor
All three measure bacteria in urban water. What separates them is what the reading is allowed to do — post a warning, open a gate for the day, or file a report with a court for eighteen years running.
| Project | Since | Status | Outcome | Evidence | Run by | Cost | What the reading does |
|---|---|---|---|---|---|---|---|
| Copenhagen Bathing Water Forecast & Overflow Warning SystemCopenhagen, 🇩🇰 | 2002 | Live | Succeeded | Official | City government, Utility or public operator | not public | Forecasts rather than measures after the fact: rainfall and sewer-overflow data estimate risk and raise a red flag before anyone gets in. |
| Seine Bathing-Water Sensing & Public Swimming ReturnParis, 🇫🇷 | 2025 | Live | Succeeded | Official | City government | not public | Decides the day. Sites open or close each morning on that morning's water-quality result, under health-authority control. |
| Pasig River: Court-Ordered Water Quality MonitoringManila, 🇵🇭 | 2008 | Live | Ongoing | Peer-reviewed | National government | not public | Reports to a court, indefinitely, and the river still fails — a court can compel measurement for decades; it cannot compel the sewers that would change the reading. |
Explore the wider context
📎 Cite this project
1001 Smart Cities (2026). “Seine Bathing-Water Sensing & Public Swimming Return” — Paris, France. The Smart City Atlas. https://1001smartcities.org/projects/paris-seine-bathing-monitoring/ (last verified 2026-08-27). Data: CC BY 4.0.
The underlying data is free to reuse with attribution — see the open data page.