PFAS in Four's tap water: 25 ng/L, 50x our 0.5 ng/L benchmark
Last PFAS check: · Source: Hub'eau
PFAS in drinking water
50× above our health benchmark
0.5 ng/L is our benchmark, not an official limit. Same EFSA method as Sweden, Denmark and the Netherlands, but stricter. It's a yearly average, compared here with the latest check.
Sample taken in La Verpillière, on the same distribution network as Four (CAPI OUEST). The health authority samples one tap per network; a network carries the same treated water everywhere.
More about this result
The US also limits PFOA and PFOS to 4 ng/L each, per substance.
Substances below the detection limit count as 0, so the real total may be higher.
One of these four, PFOA, is classified as causing cancer in humans by the WHO's cancer research agency (IARC).
More PFAS than in 99% of the cities we track
checked on 15 July 2026
20 PFAS (see each substance)
| PFAS substance | Value |
|---|---|
| Acide perfluoropentanoïque (PFPEA) | 0.017 µg/L |
| Acide sulfonique de perfluorooctane (PFOS) | 0.012 µg/L |
| Acide perfluorohexanoïque (PFHXA) | 0.011 µg/L |
| Perfluorohexane sulfonate (PFHXS) | 0.008 µg/L |
| Acide perfluorobutanoïque (PFBA) | 0.006 µg/L |
| Acide perfluoro-octanoïque (PFOA) | 0.005 µg/L |
| Acide perfluoroheptanoïque (PFHPA) | 0.004 µg/L |
| Acide sulfonique de perfluorobutane (PFBS) | 0.002 µg/L |
| Acide perfluoropentane sulfonique (PFPS) | 0.001 µg/L |
| Acide perfluoro tridecane sulfonique (PFTrDS) | <0,005 µg/L |
| Acide perfluorodecane sulfonique (PFDS) | <0,001 µg/L |
| Acide perfluorododécane sulfonique (PFDoDS) | <0,001 µg/L |
| Acide perfluoro-decanoïque (PFDA) | <0,001 µg/L |
| Acide perfluoroheptane sulfonique (PFHpS) | <0,002 µg/L |
| Acide perfluorododécanoique (PFDoDA) | <0,001 µg/L |
| Acide perfluoro undecane sulfonique (PFUnDS) | <0,002 µg/L |
| Acide perfluoro-nonanoïque (PFNA) | <0,001 µg/L |
| Acide perfluorononane sulfonique (PFNS) | <0,002 µg/L |
| Acide perfluoro undecanoïque (PFUnA) | <0,001 µg/L |
| Acide perfluoro tridecanoique (PFTrDA) | <0,001 µg/L |
Above our health benchmark. Here are some filter options.
- EU legal limit
- 66 ng/L sum of 20 PFAS, below the 100 ng/L limit
- Last PFAS test
- 15 July 2026
- Water supplier
- SEMIDAO
In Four, the 4 most closely watched PFAS (PFAS-4) add up to 25 ng/L (0.025 µg/L) at the latest PFAS check on 15 July 2026. That's 50 times our 0.5 ng/L health benchmark, and above Sweden's legal limit of 4 ng/L. Sum of 20 PFAS: 66 ng/L (0.066 µg/L), below the EU legal limit (100 ng/L). Sampled in La Verpillière, on the same network. 8 checks since 13 August 2025: PFAS-4 from 13 ng/L to 37 ng/L, averaging 29 ng/L over 12 months. No clear trend. Source: Hub'eau, Qualité de l'eau potable (Ministère de la Santé / OFB / BRGM).
Details and sources
PFAS over time in Four
33 PFAS checks since 15 April 2024, from the published measurements. Samples from 6 communes on the same network: it's the same water, so each one applies to Four. Samples come from 2 distribution networks. The trend refers to the network “CAPI OUEST”.
“Calculated”: PFAS-4 worked out from the four substances in the same sample. The chart, averages and trends use lab-published sums only.
| Date | PFAS-4 | Sum of 20 PFAS | Sampled at | Network |
|---|---|---|---|---|
| 25 ng/L | 66 ng/L | La Verpillière | CAPI OUEST, VILLEFONTAINE VAULX-MILIEU FOUR | |
| 13 ng/L | 35 ng/L | L'Isle-d'Abeau | VILLEFONTAINE VAULX-MILIEU FOUR | |
| 37 ng/L | 93 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 26 ng/L | 69 ng/L | Saint-Quentin-Fallavier | CAPI OUEST, VILLEFONTAINE VAULX-MILIEU FOUR | |
| 30 ng/L | 71 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 14 ng/L | 40 ng/L | Maubec | VILLEFONTAINE VAULX-MILIEU FOUR | |
| 30 ng/L | 82 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 28 ng/L – < 29 ng/L · calculated | 75 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 26 ng/L – < 27 ng/L · calculated | 69 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 26 ng/L | 70 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 38 ng/L – < 39 ng/L · calculated | 94 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 31 ng/L – < 32 ng/L · calculated | 86 ng/L | Villefontaine | CAPI OUEST, VILLEFONTAINE VAULX-MILIEU FOUR |
Show the 21 earlier checks (back to 15 April 2024)
| 15 ng/L – < 16 ng/L · calculated | 38 ng/L | L'Isle-d'Abeau | VILLEFONTAINE VAULX-MILIEU FOUR | |
| 29 ng/L – < 30 ng/L · calculated | 77 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 35 ng/L – < 36 ng/L · calculated | 91 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 16 ng/L – < 17 ng/L · calculated | 45 ng/L | L'Isle-d'Abeau | VILLEFONTAINE VAULX-MILIEU FOUR | |
| 30 ng/L – < 31 ng/L · calculated | 79 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 32 ng/L – < 33 ng/L · calculated | 82 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 27 ng/L – < 28 ng/L · calculated | 75 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 29 ng/L – < 30 ng/L · calculated | 73 ng/L | Vaulx-Milieu | VILLEFONTAINE VAULX-MILIEU FOUR | |
| 36 ng/L – < 37 ng/L · calculated | 95 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 32 ng/L – < 33 ng/L · calculated | 79 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 37 ng/L – < 38 ng/L · calculated | 90 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 44 ng/L – < 45 ng/L · calculated | 107 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 42 ng/L – < 43 ng/L · calculated | 104 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 44 ng/L – < 45 ng/L · calculated | 107 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 32 ng/L – < 33 ng/L · calculated | 81 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 33 ng/L – < 34 ng/L · calculated | 84 ng/L | La Verpillière | CAPI OUEST | |
| 28 ng/L – < 29 ng/L · calculated | 70 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 17.1 ng/L – < 18.1 ng/L · calculated | 48.4 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 39.8 ng/L – < 40.8 ng/L · calculated | 102 ng/L | La Verpillière | CAPI OUEST | |
| 52.2 ng/L – < 53.2 ng/L · calculated | 114.6 ng/L | Saint-Quentin-Fallavier | CAPI OUEST | |
| 48.9 ng/L – < 49.9 ng/L · calculated | 111.5 ng/L | Saint-Quentin-Fallavier | CAPI OUEST |
Calculated values: “<” is an upper bound from published thresholds, “≥” a lower bound, “–” means no published sum or complete measurement. How to read a PFAS result
What the latest check found
At the latest check, the water was within every limit tested.
See all 15 test results
| What was tested | Value | Limit | Status |
|---|---|---|---|
| Nitrate | 17.1 mg/L | ≤ 50 mg/L | within the limit |
| Nitrite | <0,01 mg/L | ≤ 0.5 mg/L | within the limit |
| Lead | 2 µg/L | ≤ 10 µg/L | within the limit |
| Copper | 0.041 mg(Cu)/L | ≤ 2 mg(Cu)/L | within the limit |
| Nickel | <5 µg/L | ≤ 20 µg/L | within the limit |
| Cadmium | <1 µg/L | ≤ 5 µg/L | within the limit |
| Chromium | <5 µg/L | ≤ 50 µg/L | within the limit |
| Escherichia coli | <1 n/(100mL) | ≤ 0 mL) | within the limit |
| Enterococci | <1 n/(100mL) | ≤ 0 mL) | within the limit |
| Coliform bacteria | <1 n/(100mL) | ≤ 0 mL) | within the limit |
| pH | 7.35 unité pH | 6.5–9 unité pH | within the limit |
| Electrical conductivity | 615 µS/cm | 200–1,100 µS/cm | within the limit |
| Chloride | 15.5 mg/L | ≤ 250 mg/L | within the limit |
| Sulphate | 15.1 mg/L | ≤ 250 mg/L | within the limit |
| Turbidity | <0,1 NFU | ≤ 2 NFU | within the limit |
Frequently asked questions
Is tap water in Four safe to drink?
Yes. At the check on 15 July 2026, the tap water in Four was within every limit tested. “Eau d'alimentation conforme aux exigences de qualité en vigueur pour l'ensemble des paramètres mesurés.”
How high are PFAS levels in Four's drinking water?
The total of 20 PFAS ("forever chemicals") was last measured at 66 ng/L. The EU limit is 100 ng/L, so this water is at 66 % of the limit. (below the EU limit)
Does the water in Four also meet the strictest limits in Europe?
No. The four most harmful PFAS add up to 25 ng/L. That is 6.3 times Sweden's legal limit of 4 ng/L, in force since 2026. Germany will set a similar one in 2028. The water still passes the current EU legal limit (100 ng/L for the total of 20 PFAS).
Are PFAS levels rising in Four's tap water?
No clear trend. Since 15 April 2024, 8 checks have been published; on the main network the PFAS-4 sum ranged between 25 ng/L and 37 ng/L (6 quantified values), at times below the detection limit. pfasnearme only reports a trend from a change of at least 25 % and 1 ng/L. These history statistics use laboratory-published sums only.
How hard is the water in Four?
No hardness value is available for Four in this source.
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 21 September 2026.
Same water network
Same distribution network as Four, so in principle the same water.
Nearby communes
The closest to Four on this site.
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=38172
- License
- Licence Ouverte / Open Licence (Etalab)
- Retrieved
- 21 September 2026
- Supply networks
- CAPI OUEST, VILLEFONTAINE VAULX-MILIEU FOUR
Water report for Four
Get new PFAS results for Four, with a short explanation. At most one update a week, only when there's something new.
This site is a data project, not an official source. If in doubt, check with your water supplier or local authority.