PFAS in tap water: Aomori Prefecture
In Aomori Prefecture’s water supplies, the highest combined PFOS and PFOA value for FY2020–FY2025 (FY2025 through the end of August) was 5 ng/L at the Kuroishi City water utility (黒石市水道事業) (FY2024 and FY2025, tap). No utility exceeded 50 ng/L, and of the 54 rows with a testing record, 52 were nd (below the detection or quantification limit) in every result.
Levels by utility (PFOS + PFOA combined, ng/L)
| Utility | FY2020 | FY2021 | FY2022 | FY2023 | FY2024 | FY2025* | Sampled at |
|---|---|---|---|---|---|---|---|
| 黒石市水道事業Water supply · 黒石市 | — | — | — | — | 5 | 5 | tap only |
| 五所川原市水道事業Water supply · 五所川原市 | — | — | — | — | nd | nd | raw water only |
| 十和田市水道事業Water supply · 十和田市 | — | — | — | nd | — | — | raw water only |
| 三沢市水道事業Water supply · 三沢市 | — | — | 3 | 3 | 3 | 2 | raw water only |
| むつ市上下水道局Water supply · むつ市 | — | — | — | — | nd | nd | raw water only |
| 平川市水道事業Water supply · 平川市buys all its water — Buys from 津軽広域水道企業団津軽事業部 | — | — | — | — | — | — | — |
| 平内町水道事業Water supply · 平内町 | — | — | — | — | nd | nd | raw water only |
| 鯵ヶ沢町水道事業Water supply | — | — | — | nd | — | — | raw water only |
| 深浦町水道事業Water supply · 深浦町 | — | — | — | — | — | nd | — |
| 藤崎町水道事業Water supply · 藤崎町buys all its water — Buys from 津軽広域水道企業団津軽事業部 | — | — | — | nd | — | nd | plant outlet only |
| 田舎館村水道事業Water supply · 田舎館村buys all its water — Buys from 津軽広域水道企業団津軽事業部 | — | — | — | — | — | — | — |
| 板柳町水道事業Water supply · 板柳町buys all its water — Buys from 津軽広域水道企業団津軽事業部 | — | — | — | — | — | nd | — |
| 鶴田町水道事業Water supply · 鶴田町buys all its water — Buys from 津軽広域水道企業団津軽事業部 | — | — | — | — | nd | nd | tap only |
| 中泊町水道事業Water supply · 中泊町 | — | — | — | — | — | nd | — |
| 野辺地町水道事業Water supply · 野辺地町 | — | — | — | — | nd | nd | raw water only |
| 七戸町水道事業Water supply · 七戸町 | — | — | — | — | nd | — | raw water only |
| 東北町水道事業Water supply · 東北町 | — | — | — | nd | nd | nd | raw water only |
| 六ヶ所村水道事業Water supply · 六ヶ所村 | — | nd | nd | nd | nd | nd | raw water only |
| 大間町水道事業Water supply · 大間町 | — | — | — | — | nd | nd | raw water only |
| 東通村水道事業Water supply · 東通村 | — | — | — | — | nd | nd | raw water only |
| 田子町水道事業Water supply · 田子町 | — | — | — | — | nd | — | raw water only |
| 久吉ダム水道企業団水道事業Water supply | — | — | — | nd | nd | — | raw water only |
| 津軽広域水道企業団水道事業Water supplybuys all its water — Buys from 津軽広域水道企業団津軽事業部 | — | — | — | — | — | nd | — |
| 弘前市上下水道事業Water supply · 弘前市 | — | nd | nd | nd | nd | nd | raw water only |
| 八戸圏域水道企業団Water supply | nd | nd | nd | nd | nd | — | plant outlet and raw |
| 青森市企業局水道部Water supply · 青森市 | nd | nd | nd | nd | nd | nd | tap, plant outlet and raw |
| 津軽広域水道企業団津軽事業部Bulk supplierSupplies: 弘前市（旧弘前市域）、黒石市、五所川原市（旧五所川原市域）、平川市（旧尾上町・平賀町域）、青森市（旧浪岡町域）、藤崎町、田舎館村、板柳町、鶴田町、津軽広域水道企業団水道事業（西北事業部） | nd | nd | nd | nd | nd | nd | plant outlet and raw |
| 青森市雲谷地区簡易水道事業Small water supply · 青森市 | — | — | — | nd | nd | nd | tap and raw |
| 青森市入内地区簡易水道事業Small water supply · 青森市 | — | — | — | — | nd | nd | tap and raw |
| 青森市孫内地区簡易水道事業Small water supply · 青森市 | — | — | — | — | nd | nd | tap and raw |
| 青森市岩渡地区簡易水道事業Small water supply · 青森市 | — | — | — | — | nd | nd | tap and raw |
| 青森市王余魚沢地区簡易水道事業Small water supply · 青森市 | — | — | — | — | nd | nd | tap and raw |
| 青森市細野相沢地区簡易水道事業Small water supply · 青森市 | — | — | — | — | nd | nd | tap and raw |
| 黒石市南中野地区簡易水道事業Small water supply · 黒石市 | — | — | — | — | — | planned | — |
| 黒石市温湯地区簡易水道事業Small water supply · 黒石市 | — | — | — | — | — | nd | — |
| 黒石市板留地区簡易水道事業Small water supply · 黒石市 | — | — | — | — | — | planned | — |
| 十和田市滝沢地区簡易水道Small water supply · 十和田市 | — | — | — | — | nd | — | — |
| 十和田市清瀬・万内地区簡易水道Small water supply · 十和田市 | — | — | — | — | nd | — | — |
| 十和田市長下地区簡易水道Small water supply · 十和田市 | — | — | — | — | nd | — | — |
| 十和田市十和田湖畔地区簡易水道Small water supply · 十和田市 | — | — | — | — | nd | — | — |
| 十和田市焼山地区簡易水道Small water supply · 十和田市 | — | — | — | nd | — | — | raw water only |
| 平川市小国地区簡易水道事業Small water supply · 平川市 | — | — | — | — | — | nd | — |
| 平川市葛川地区簡易水道事業Small water supply · 平川市 | — | — | — | — | — | nd | — |
| 今別町簡易水道事業Small water supply · 今別町 | — | — | — | — | — | nd | — |
| 蓬田村簡易水道事業Small water supply · 蓬田村 | — | — | — | — | — | nd | — |
| 外ヶ浜町簡易水道事業Small water supply · 外ヶ浜町 | — | — | — | — | nd | nd | tap and raw |
| 外ヶ浜町三厩簡易水道事業Small water supply · 外ヶ浜町 | — | — | — | — | nd | nd | tap and raw |
| 西目屋村簡易水道事業Small water supply · 西目屋村 | — | — | — | — | nd | nd | raw water only |
| 大鰐町駒木地区簡易水道事業Small water supply · 大鰐町 | — | — | — | — | nd | — | raw water only |
| 大鰐町唐牛地区簡易水道事業Small water supply · 大鰐町 | — | — | — | — | nd | — | raw water only |
| 大鰐町島田地区簡易水道事業Small water supply · 大鰐町 | — | — | — | — | nd | — | raw water only |
| 横浜町横浜地区簡易水道事業Small water supply · 横浜町 | — | — | — | — | nd | — | — |
| 風間浦村簡易水道事業Small water supply · 風間浦村 | — | — | — | nd | — | nd | raw water only |
| 佐井村簡易水道事業Small water supply · 佐井村 | — | — | — | nd | nd | nd | raw water only |
| 三戸町簡易水道事業Small water supply · 三戸町 | — | — | — | nd | — | — | raw water only |
| 五戸町切谷内地区簡易水道事業Small water supply · 五戸町 | — | — | — | — | — | nd | — |
| 五戸町上区簡易水道事業Small water supply · 五戸町 | — | — | — | — | — | nd | — |
| 五戸町簡易水道事業Small water supply · 五戸町 | — | — | — | — | — | nd | — |
| 新郷村簡易水道事業Small water supply · 新郷村 | — | — | — | — | — | planned | — |
These are the highest values in each fiscal year reported by each utility to the national government (MLIT and the Ministry of the Environment). A utility with several sources or treatment plants can have different levels in different parts of its area. Samples are taken at the tap in principle, but some utilities only measured raw water (water before treatment), and raw-water values are not covered by the tap-water standard. nd = below the detection or quantification limit; — = no value reported. *FY2025 covers results up to the end of August 2025. Utility names are left in Japanese as in the official table.
>50 a year above 50 ng/L (for utilities that also sampled raw water, the value may be from raw water) raw above 50 ng/L, but measured in raw water only
Good to know
- Numbers appeared only for Kuroishi City (5) and Misawa City (三沢市) (2–3, measured in raw water, i.e. water before treatment at the plant). The Aomori City Public Enterprise Bureau Waterworks Department (青森市企業局水道部) and the Tsugaru Regional Water Supply Authority (津軽広域水道企業団) (a bulk water supplier) were nd for all six years.
- Six utilities buy all their water from a bulk supplier (they have no water sources of their own and buy water from another utility). They may not test the water themselves, so check the values of their supplier. → How to read the national table
- Private water supplies (for facilities such as company housing and hospitals) were tested at 46 of the 76 operators, and no exceedance of the provisional target value has been confirmed (through the end of August 2025).
Put it in terms of your own intake
- Intake from water
- — ng/kg/day
- Compared with Japan’s tolerable daily intake (PFOS and PFOA, 20 ng/kg bw/day each)
- —
- Compared with EFSA’s tolerable weekly intake (4 PFAS combined, 4.4 ng/kg bw/week ≈ 0.63 a day)
- —
- Compared with intake from 37 foods (MAFF estimate: PFOS 0.13 + PFOA 0.09 = 0.22 ng/kg bw/day; the 37 foods make up about half of what people eat by amount)
- —
The combined value is treated as a single substance (in reality it is split between PFOS and PFOA, so the share of Japan’s TDI would be smaller). EFSA’s value is for the sum of PFOA, PFNA, PFHxS and PFOS; tap-water values here do not include PFNA or PFHxS. This calculation shows how the same intake reads differently against different yardsticks; it does not judge health effects.
Related explainers
Sources
- Ministry of the Environment and MLIT, “Results of the follow-up survey on PFOS and PFOA in water supplies” (December 25, 2025)
- Same, list of survey results (updated), Excel (annual maximums, FY2020–FY2025)
- Ministry of the Environment and MLIT, list of survey results, Excel (published November 29, 2024; sampling point column)
- Same, follow-up survey annex (status of private water supplies by prefecture)
Last checked 2026.10.04 (against the original government documents and papers, collected and cross-checked in Gemini Notebook). Utility values are as in the national table; Urayomi sorted and summarized them.