Drinking water quality in Saint-Jouan-des-Guérets
PFAS in drinking water
The total of 20 PFAS ("forever chemicals") was last measured at 0.0054 µg/L. The EU limit is 0.1 µg/L, so this water is at 5 % of the limit. (14 January 2026)
The four most harmful PFAS add up to 0.0017 µg/L, below the health limit of 0.004 µg/L used in Sweden since 2026.
One of these four, PFOA, is classified as causing cancer in humans by the WHO's cancer research agency (IARC).
Substances too small to measure count as 0, so the real total may be higher.
20 PFAS (see each substance)
| Acide perfluorohexanoïque (PFHXA) | 0.0019 µg/L |
| Acide perfluoroheptanoïque (PFHPA) | 0.0012 µg/L |
| Acide perfluoro-octanoïque (PFOA) | 0.0011 µg/L |
| Perfluorohexane sulfonate (PFHXS) | 0.0006 µg/L |
| Acide sulfonique de perfluorobutane (PFBS) | 0.0006 µg/L |
| Acide perfluoro-nonanoïque (PFNA) | <0,0010 µg/L |
| Acide perfluoro tridecanoique (PFTrDA) | <0,0010 µg/L |
| Acide perfluorononane sulfonique (PFNS) | <0,00040 µg/L |
| Acide perfluoropentane sulfonique (PFPS) | <0,00040 µg/L |
| Acide perfluoro undecanoïque (PFUnA) | <0,0010 µg/L |
| Acide perfluorododécane sulfonique (PFDoDS) | <0,00040 µg/L |
| Acide perfluoropentanoïque (PFPEA) | <0,0050 µg/L |
| Acide perfluoro undecane sulfonique (PFUnDS) | <0,00040 µg/L |
| Acide perfluoro-decanoïque (PFDA) | <0,0010 µg/L |
| Acide perfluoroheptane sulfonique (PFHpS) | <0,00040 µg/L |
| Acide perfluorododécanoique (PFDoDA) | <0,0010 µg/L |
| Acide perfluorobutanoïque (PFBA) | <0,0050 µg/L |
| Acide perfluoro tridecane sulfonique (PFTrDS) | <0,00040 µg/L |
| Acide perfluorodecane sulfonique (PFDS) | <0,00040 µg/L |
| Acide sulfonique de perfluorooctane (PFOS) | <0,0010 µg/L |
Water report for Saint-Jouan-des-Guérets
Get the free water report for Saint-Jouan-des-Guérets, plus an alert whenever new official results are published.
Official assessment
The latest official test passed all quality requirements.
„Eau d'alimentation conforme aux limites réglementaires en vigueur, mai s ne respectant pas la référence de qualité fixée pour le paramètre te mpérature en ce point d'échantillonage. Il convient également de noter l'absence de chlore résiduel sur ce secteur de distribution. D'une façon générale, la présence d'un résiduel de chlore est nécessaire pour se prémunir de la prolifération bactérienne dans les réseaux (objectif souhaitable : 0,1 mg/L de chlore libre). L'exploitant a été informé de cette situation dès connaissance de celle-ci par mon service, pour vérifications et actions correctives d'usage.“
Show all 21 official measurements
| Parameter | Value | Limit | Status |
|---|---|---|---|
| Nitrate | 9.5 mg/L | ≤ 50 mg/L | within limit |
| Nitrite | <0,02 mg/L | ≤ 0.5 mg/L | within limit |
| Lead | <1,0 µg/L | ≤ 10 µg/L | within limit |
| Copper | <0,0010 mg(Cu)/L | ≤ 2 mg(Cu)/L | within limit |
| Nickel | 2 µg/L | ≤ 20 µg/L | within limit |
| Arsenic | 0.34 µg/L | ≤ 10 µg/L | within limit |
| Cadmium | <0,025 µg/L | ≤ 5 µg/L | within limit |
| Chromium | <1,0 µg/L | ≤ 50 µg/L | within limit |
| Uranium | <0,50 µg/L | ≤ 30 µg/L | within limit |
| Fluoride | 0.104 mg/L | ≤ 1.5 mg/L | within limit |
| Escherichia coli | 0 n/(100mL) | ≤ 0 mL) | within limit |
| Enterococci | 0 n/(100mL) | ≤ 0 mL) | within limit |
| Coliform bacteria | 0 n/(100mL) | ≤ 0 mL) | within limit |
| pH | 8.1 unité pH | 6.5–9 unité pH | within limit |
| Water hardness | 17.6 °f | no limit | informational |
| Electrical conductivity | 489 µS/cm | 200–1,100 µS/cm | within limit |
| Chloride | 76.3 mg/L | ≤ 250 mg/L | within limit |
| Sulphate | 24.8 mg/L | ≤ 250 mg/L | within limit |
| Sodium | 28.5 mg/L | ≤ 200 mg/L | within limit |
| Iron | <20 µg/L | ≤ 200 µg/L | within limit |
| Turbidity | <0,20 NFU | ≤ 2 NFU | within limit |
Frequently asked questions
Is tap water in Saint-Jouan-des-Guérets safe to drink?
Yes. The latest official test (26 May 2026) checked the tap water in Saint-Jouan-des-Guérets and it passed every requirement.
How high are PFAS levels in Saint-Jouan-des-Guérets's drinking water?
The total of 20 PFAS ("forever chemicals") was last measured at 0.0054 µg/L. The EU limit is 0.1 µg/L, so this water is at 5 % of the limit. (below the EU limit)
Does the water in Saint-Jouan-des-Guérets also meet the strictest limits in Europe?
Yes. Even against Europe's strictest limit, the health limit of 0.004 µg/L used in Sweden since 2026, the measured value of 0.0017 µg/L stays below.
How hard is the water in Saint-Jouan-des-Guérets?
The water hardness in Saint-Jouan-des-Guérets is 17.6 °f (medium). This mainly matters for household appliances and detergent dosing, not for health.
Where does this data come from?
All values come from official publications: Hub'eau, Qualité de l'eau potable (Ministère de la Santé / OFB / BRGM). Retrieved on 28 August 2026.
Data source
- Hub'eau, Qualité de l'eau potable (Ministère de la Santé / OFB / BRGM)
- https://hubeau.eaufrance.fr/api/v1/qualite_eau_potable/resultats_dis?code_commune=35284
- License
- Licence Ouverte / Open Licence (Etalab)
- Retrieved
- 28 August 2026
- Supply networks
- BEAUFORT_BEAUFORT_DOL DE BRETAGNE
This site is a data project, not an official source. If in doubt, check with your water supplier or local authority.