pfasnearmeDrinking water quality from official sources

PFAS in Osny's tap water: under 4 ng/L, none of the four main PFAS detected

Last PFAS check: · Source: Hub'eau

PFAS in drinking water

None of the 4 most harmful PFAS detected

Amount found in the water < 4 ng/L the 4 most harmful PFAS (PFAS-4) · the lab's detection limit 20 PFAS looked for, 1 ng/L found in total
Our health benchmark 0.5 ng/L

The lab sees nothing below 4 ng/L, 8 times our benchmark of 0.5 ng/L. Water above our benchmark would pass this check unnoticed.

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.

How we chose 0.5 ng/L

Sample taken in Méry-sur-Oise, on the same distribution network as Osny (CACP NORD). The health authority samples one tap per network; a network carries the same treated water everywhere.

More about this result
Legal limit in Sweden (since 2026) within the limit
below this limit < 4 ng/L · Limit: 4 ng/L
Limit in Denmark (since 2021) no verdict
finer than the lab's detection limit < 4 ng/L · Limit: 2 ng/L
Limit in Germany (from 2028) within the limit
below this limit < 4 ng/L · Limit: 20 ng/L

The US also limits PFOA and PFOS to 4 ng/L each, per substance.

The lab detects each of the four substances from 1 ng/L upward. None reached that limit, so their total is below 4 ng/L rather than zero.

EU legal limit within the limit
1 % of the EU limit 0.001 µg/L · Limit: 0.1 µg/L

checked on 25 March 2026

20 PFAS (see each substance)
PFAS substance Value
Acide perfluoropentanoïque (PFPEA) 0.001 µg/L
Acide perfluorododécanoique (PFDoDA) <0,001 µg/L
Acide sulfonique de perfluorooctane (PFOS) <0,001 µg/L
Acide sulfonique de perfluorobutane (PFBS) <0,001 µg/L
Acide perfluoro-octanoïque (PFOA) <0,0010 µg/L
Acide perfluoro tridecane sulfonique (PFTrDS) <0,005 µg/L
Acide perfluorohexanoïque (PFHXA) <0,002 µg/L
Acide perfluorodecane sulfonique (PFDS) <0,001 µg/L
Acide perfluoro-decanoïque (PFDA) <0,001 µg/L
Acide perfluorobutanoïque (PFBA) <0,002 µg/L
Acide perfluoro undecane sulfonique (PFUnDS) <0,002 µg/L
Acide perfluoroheptanoïque (PFHPA) <0,001 µg/L
Acide perfluoro-nonanoïque (PFNA) <0,001 µg/L
Acide perfluorononane sulfonique (PFNS) <0,002 µg/L
Acide perfluorododécane sulfonique (PFDoDS) <0,001 µg/L
Perfluorohexane sulfonate (PFHXS) <0,001 µg/L
Acide perfluoroheptane sulfonique (PFHpS) <0,002 µg/L
Acide perfluoro undecanoïque (PFUnA) <0,001 µg/L
Acide perfluoro tridecanoique (PFTrDA) <0,001 µg/L
Acide perfluoropentane sulfonique (PFPS) <0,001 µg/L

None found. The lab sees nothing below 4 ng/L, so our 0.5 ng/L benchmark cannot be checked.

EU legal limit
1 ng/L sum of 20 PFAS, below the 100 ng/L limit
Last PFAS test
25 March 2026
Water supplier
CYO'

In Osny, none of the 4 most closely watched PFAS (PFAS-4) was detected at the latest PFAS check on 25 March 2026. The total is below 4 ng/L, the sum of the detection limits and 8 times our 0.5 ng/L benchmark. Sum of 20 PFAS: 1 ng/L (0.001 µg/L), below the EU legal limit (100 ng/L). Sampled in Méry-sur-Oise, on the same network. 28 checks since 24 January 2025: sum of 20 PFAS up to 37 ng/L, sometimes below the detection limit. Source: Hub'eau, Qualité de l'eau potable (Ministère de la Santé / OFB / BRGM).

Details and sources
Water supplier: CYO' Latest water check: 25 March 2026 Data updated on

PFAS over time in Osny

28 PFAS checks since 24 January 2025, from the published measurements. Samples from 3 communes on the same network: it's the same water, so each one applies to Osny. Samples come from 2 distribution networks. The trend refers to the network “CACP NORD”.

“Calculated”: PFAS-4 worked out from the four substances in the same sample. The chart, averages and trends use lab-published sums only.

37 ng/L024 January 202525 March 2026
Laboratory-published sum of 20 PFAS per check in ng/L. Hollow dots: below the detection limit. Calculated PFAS-4 values are listed in the table.
DatePFAS-4Sum of 20 PFASSampled atNetwork
< 4 ng/L · calculated1 ng/LMéry-sur-OiseCACP NORD
9 ng/L – < 10 ng/L · calculated17 ng/LOsnyOSNY PIGEONNIER
< 4 ng/L · calculated< 29 ng/LMéry-sur-OiseCACP NORD
< 4 ng/L · calculated3 ng/LMéry-sur-OiseCACP NORD
< 4 ng/L · calculated2 ng/LCergyCACP NORD
< 4 ng/L · calculated< 29 ng/LMéry-sur-OiseCACP NORD
< 4 ng/L · calculated< 29 ng/LMéry-sur-OiseCACP NORD
1 ng/L – < 4 ng/L · calculated10 ng/LMéry-sur-OiseCACP NORD
< 4 ng/L · calculated2 ng/LMéry-sur-OiseCACP NORD
11 ng/L – < 12 ng/L · calculated23 ng/LOsnyCACP NORD
< 4 ng/L · calculated6 ng/LOsnyCACP NORD
< 4 ng/L · calculated3 ng/LMéry-sur-OiseCACP NORD
Show the 16 earlier checks (back to 24 January 2025)
2 ng/L – < 4 ng/L · calculated10 ng/LOsnyCACP NORD
1 ng/L – < 4 ng/L · calculated9 ng/LMéry-sur-OiseCACP NORD
6 ng/L – < 7 ng/L · calculated13 ng/LOsnyOSNY PIGEONNIER
1 ng/L – < 4 ng/L · calculated6 ng/LMéry-sur-OiseCACP NORD
< 4 ng/L · calculated3 ng/LMéry-sur-OiseCACP NORD
1 ng/L – < 4 ng/L · calculated10 ng/LMéry-sur-OiseCACP NORD
17 ng/L – < 18 ng/L · calculated31 ng/LOsnyCACP NORD
< 4 ng/L · calculated4 ng/LMéry-sur-OiseCACP NORD
< 4 ng/L · calculated4 ng/LOsnyCACP NORD
< 4 ng/L · calculated7 ng/LMéry-sur-OiseCACP NORD
7 ng/L – < 8 ng/L · calculated14 ng/LOsnyOSNY PIGEONNIER
8 ng/L – < 9 ng/L · calculated13 ng/LOsnyOSNY PIGEONNIER
< 4 ng/L · calculated2 ng/LMéry-sur-OiseCACP NORD
18 ng/L – < 19 ng/L · calculated37 ng/LOsnyCACP NORD
< 4 ng/L · calculated1 ng/LMéry-sur-OiseCACP NORD
< 4 ng/L · calculated< 1 ng/LMéry-sur-OiseCACP NORD

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.

Microbiology: within the limit Chemistry: within the limit

Values to watch

These results are close to their legal limit, or over it.

What was tested Value Limit Status
Nitrate 25.4 mg/L ≤ 50 mg/L within the limit
Lead 5 µg/L ≤ 10 µg/L within the limit
See all 21 test results
What was tested Value Limit Status
Nitrate 25.4 mg/L ≤ 50 mg/L within the limit
Nitrite <0,01 mg/L ≤ 0.1 mg/L within the limit
Lead 5 µg/L ≤ 10 µg/L within the limit
Copper 0.227 mg(Cu)/L ≤ 2 mg(Cu)/L within the limit
Nickel <5 µg/L ≤ 20 µg/L within the limit
Arsenic <2 µg/L ≤ 10 µg/L within the limit
Cadmium <1 µg/L ≤ 5 µg/L within the limit
Chromium <5,00 µg/L ≤ 50 µg/L within the limit
Uranium <10 µg/L ≤ 30 µg/L within the limit
Fluoride 0.11 mg/L ≤ 1.5 mg/L within the limit
Escherichia coli 0 n/(100mL) ≤ 0 mL) within the limit
Enterococci 0 n/(100mL) ≤ 0 mL) within the limit
Coliform bacteria 0 n/(100mL) ≤ 0 mL) within the limit
pH 7.5 unité pH 6.5–9 unité pH within the limit
Water hardness 28.13 °f no limit for reference
Electrical conductivity 629 µS/cm 200–1,100 µS/cm within the limit
Chloride 27.2 mg/L ≤ 250 mg/L within the limit
Sulphate 49.6 mg/L ≤ 250 mg/L within the limit
Sodium 14.4 mg/L ≤ 200 mg/L within the limit
Iron <10 µg/L ≤ 200 µg/L within the limit
Turbidity 0.16 NFU ≤ 2 NFU within the limit

Frequently asked questions

Is tap water in Osny safe to drink?

Yes. At the check on 25 March 2026, the tap water in Osny 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 Osny's drinking water?

The total of 20 PFAS ("forever chemicals") was last measured at 1 ng/L. The EU limit is 100 ng/L, so this water is at 1 % of the limit. (below the EU limit)

Does the water in Osny also meet the strictest limits in Europe?

As far as this check can tell, yes. None of the four compounds was quantified, so their total is below 4 ng/L, the sum of the laboratory's detection limits, and under Sweden's legal limit of 4 ng/L in force since 2026.

Are PFAS levels rising in Osny's tap water?

Calculated PFAS-4 values are listed in the table. The chart uses laboratory-published sum-of-20 results; there are too few laboratory-published PFAS-4 sums for the existing trend calculation.

How hard is the water in Osny?

The water hardness in Osny is 28.1 °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 12 September 2026.

Same water network

Same distribution network as Osny, so in principle the same water.

Cergy
PFAS-4: below 4 ng/L
Pontoise
PFAS-4: below 4 ng/L

Nearby communes

The closest to Osny on this site.

Boissy-l'Aillerie
no PFAS result published 3 km away
Génicourt
PFAS-4: below 4 ng/L 3 km away
Puiseux-Pontoise
PFAS-4: below 4 ng/L 4 km away
Ennery
PFAS-4: below 4 ng/L 4 km away
Livilliers
PFAS-4: below 4 ng/L 4 km away

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=95476
License
Licence Ouverte / Open Licence (Etalab)
Retrieved
12 September 2026
Supply networks
OSNY PIGEONNIER, CACP NORD

This site is a data project, not an official source. If in doubt, check with your water supplier or local authority.