Drinking water quality in Saint-Cast-le-Guildo
PFAS in drinking water
The total of 20 PFAS ("forever chemicals") was last measured at <SEUIL µg/L. The EU limit is 0.1 µg/L, so this water is at 0 % of the limit. (28 April 2026)
The four most harmful PFAS add up to 0 µg/L, below the health limit of 0.004 µg/L used in Sweden since 2026.
Substances too small to measure count as 0, so the real total may be higher.
20 PFAS (see each substance)
| Perfluorohexane sulfonate (PFHXS) | <0,002 µg/L |
| Acide perfluorodecane sulfonique (PFDS) | <0,001 µg/L |
| Acide perfluoropentane sulfonique (PFPS) | <0,001 µg/L |
| Acide perfluoroheptanoïque (PFHPA) | <0,005 µg/L |
| Acide perfluorobutanoïque (PFBA) | <0,005 µg/L |
| Acide perfluoro undecanoïque (PFUnA) | <0,002 µg/L |
| Acide perfluoro-octanoïque (PFOA) | <0,002 µg/L |
| Acide perfluorohexanoïque (PFHXA) | <0,005 µg/L |
| Acide perfluoropentanoïque (PFPEA) | <0,002 µg/L |
| Acide perfluoro tridecanoique (PFTrDA) | <0,002 µg/L |
| Acide sulfonique de perfluorooctane (PFOS) | <0,001 µg/L |
| Acide perfluoro undecane sulfonique (PFUnDS) | <0,001 µg/L |
| Acide perfluoro-nonanoïque (PFNA) | <0,001 µg/L |
| Acide perfluoro-decanoïque (PFDA) | <0,002 µg/L |
| Acide sulfonique de perfluorobutane (PFBS) | <0,005 µg/L |
| Acide perfluorododécanoique (PFDoDA) | <0,002 µg/L |
| Acide perfluorononane sulfonique (PFNS) | <0,001 µg/L |
| Acide perfluoro tridecane sulfonique (PFTrDS) | <0,001 µg/L |
| Acide perfluoroheptane sulfonique (PFHpS) | <0,002 µg/L |
| Acide perfluorododécane sulfonique (PFDoDS) | <0,001 µg/L |
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Official assessment
The latest official test passed all quality requirements.
„Eau d'alimentation conforme aux exigences de qualité en vigueur pour l'ensemble des paramètres mesurés.“
Values to watch
These values are at least halfway to their legal limit, or over it.
| Parameter | Value | Limit | Status |
|---|---|---|---|
| Nitrate | 26 mg/L | ≤ 50 mg/L | within limit |
Show all 18 official measurements
| Parameter | Value | Limit | Status |
|---|---|---|---|
| Nitrate | 26 mg/L | ≤ 50 mg/L | within limit |
| Nitrite | <0,01 mg/L | ≤ 0.5 mg/L | within limit |
| Arsenic | <0,5 µg/L | ≤ 10 µg/L | within limit |
| Cadmium | <0,025 µg/L | ≤ 5 µg/L | within limit |
| Chromium | <0,5 µg/L | ≤ 50 µg/L | within limit |
| Uranium | <0,5 µg/L | ≤ 30 µg/L | within limit |
| Fluoride | 0.094 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 | 8.3 unité pH | 6.5–9 unité pH | within limit |
| Water hardness | 13 °f | no limit | informational |
| Electrical conductivity | 420 µS/cm | 200–1,100 µS/cm | within limit |
| Chloride | 63 mg/L | ≤ 250 mg/L | within limit |
| Sulphate | 23 mg/L | ≤ 250 mg/L | within limit |
| Sodium | 23 mg/L | ≤ 200 mg/L | within limit |
| Iron | <2,5 µg/L | ≤ 200 µg/L | within limit |
| Turbidity | 0.36 NFU | ≤ 2 NFU | within limit |
Frequently asked questions
Is tap water in Saint-Cast-le-Guildo safe to drink?
Yes. The latest official test (10 June 2026) checked the tap water in Saint-Cast-le-Guildo and it passed every requirement.
How high are PFAS levels in Saint-Cast-le-Guildo's drinking water?
The total of 20 PFAS ("forever chemicals") was last measured at <SEUIL µg/L. The EU limit is 0.1 µg/L, so this water is at 0 % of the limit. (below the EU limit)
Does the water in Saint-Cast-le-Guildo 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 µg/L stays below.
How hard is the water in Saint-Cast-le-Guildo?
The water hardness in Saint-Cast-le-Guildo is 13 °f (soft). 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=22282
- License
- Licence Ouverte / Open Licence (Etalab)
- Retrieved
- 28 August 2026
- Supply networks
- SAINT CAST LE GUILDO
This site is a data project, not an official source. If in doubt, check with your water supplier or local authority.