PFAS in tap water database (Japan)KantoChecked 2026.10.04
PFAS in tap water: Gunma Prefecture
Highest, FY2020–202564 ng/L渋川市水道事業（2022）
Highest, FY2025 (to Aug)50 ng/L
Utilities with a year above 50 ng/L1渋川市水道事業
Utilities with values125 / 139
In Gunma Prefecture’s water supplies, the highest combined PFOS and PFOA value for FY2020–FY2025 (FY2025 through the end of August) was 64 ng/L at the Shibukawa City water utility (渋川市水道事業) (FY2022). Shibukawa City was 40 in FY2024 and 50 in FY2025, which are also the prefecture’s maximums for FY2024 and FY2025.
Levels by utility (PFOS + PFOA combined, ng/L)
| Utility | FY2020 | FY2021 | FY2022 | FY2023 | FY2024 | FY2025* | Sampled at |
|---|---|---|---|---|---|---|---|
| 高崎市水道事業Water supply · 高崎市 | 7 | nd | 33 | 13 | 27 | 21 | raw water only |
| 沼田市上水道事業Water supply · 沼田市 | nd | nd | nd | nd | nd | nd | raw water only |
| 前橋市水道事業Water supply · 前橋市 | 6 | 6 | nd | nd | 7 | 6 | plant outlet and raw |
| 桐生市水道事業Water supply · 桐生市 | nd | — | — | — | 6 | 10 | raw water only |
| 伊勢崎市水道事業Water supply · 伊勢崎市 | nd | nd | nd | nd | nd | nd | tap, plant outlet and raw |
| 安中市水道事業Water supply · 安中市 | nd | nd | nd | nd | nd | nd | tap and raw |
| 富岡市水道事業Water supply · 富岡市 | nd | nd | nd | nd | nd | nd | raw water only |
| 下仁田町水道事業Water supply · 下仁田町 | — | — | — | — | nd | — | tap only |
| 草津町上水道事業Water supply · 草津町 | — | — | — | — | nd | — | — |
| 藤岡市水道事業Water supply · 藤岡市 | — | — | — | — | 14 | 7 | raw water only |
| 東吾妻町水道事業Water supply · 東吾妻町 | — | — | — | nd | — | — | tap only |
| 吉岡町水道事業Water supply · 吉岡町 | — | — | — | nd | — | nd | raw water only |
| 中之条町上水道事業Water supply · 中之条町 | nd | nd | nd | nd | nd | nd | raw water only |
| みなかみ町上水道事業Water supply · みなかみ町 | — | — | — | nd | — | — | tap only |
| 榛東村上水道事業Water supply · 榛東村 | — | — | — | nd | — | — | raw water only |
| 甘楽町上水道事業Water supply · 甘楽町 | — | — | — | — | nd | — | — |
| 嬬恋村上水道事業Water supply · 嬬恋村 | — | — | — | — | nd | — | — |
| 玉村町水道事業Water supply · 玉村町 | — | — | — | — | nd | nd | raw water only |
| 渋川市水道事業Water supply · 渋川市 | 37 | 50 | 64 | 23 | 40 | 50 | tap and raw |
| 群馬東部水道企業団水道事業Water supply | 6 | nd | 5 | 6 | 5 | nd | — |
| 群馬県企業局（群馬県水道用水供給事業）Bulk supplierSupplies: 前橋市、高崎市、桐生市、伊勢崎市、渋川市、榛東村、吉岡町、玉村町 | — | nd | nd | nd | nd | nd | — |
| 高崎市 倉渕地区中部簡易水道Small water supply · 高崎市 | — | — | — | — | nd | nd | raw water only |
| 高崎市 倉渕地区三ノ倉簡易水道Small water supply · 高崎市 | — | — | — | — | nd | nd | raw water only |
| 高崎市 倉渕地区川浦簡易水道Small water supply · 高崎市 | — | — | — | — | nd | nd | raw water only |
| 高崎市 倉渕地区相満簡易水道Small water supply · 高崎市 | — | — | — | — | nd | nd | raw water only |
| 高崎市 箕郷地区上善地簡易水道Small water supply · 高崎市 | — | — | — | — | nd | nd | raw water only |
| 高崎市 箕郷地区中善地簡易水道Small water supply · 高崎市 | — | — | — | — | nd | nd | raw water only |
| 高崎市 榛名地区社家町簡易水道Small water supply · 高崎市 | — | — | — | — | nd | nd | raw water only |
| 高崎市 榛名地区湖畔簡易水道Small water supply · 高崎市 | — | — | — | nd | — | nd | raw water only |
| 高崎市 榛名地区沼ノ原簡易水道Small water supply · 高崎市 | — | — | — | — | 16 | nd | raw water only |
| 高崎市 榛名地区本庄・中戸簡易水道Small water supply · 高崎市 | — | — | — | — | nd | nd | raw water only |
| 高崎市 榛名地区中室田簡易水道Small water supply · 高崎市 | — | — | — | nd | — | nd | raw water only |
| 高崎市 榛名地区上室田原簡易水道Small water supply · 高崎市 | — | — | — | nd | — | nd | raw water only |
| 高崎市 榛名地区北の谷簡易水道Small water supply · 高崎市 | — | — | — | — | nd | nd | raw water only |
| 高崎市 榛名地区中室田北部簡易水道Small water supply · 高崎市 | — | — | — | — | nd | nd | raw water only |
| 高崎市 榛名地区斉渡簡易水道Small water supply · 高崎市 | — | — | — | — | nd | — | — |
| 高崎市 倉渕地区川浦西簡易水道Small water supply · 高崎市 | — | — | — | — | nd | nd | raw water only |
| 沼田市 下久屋上簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 佐山簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 発知簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 奈良大倉簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 硯田簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 三峯簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 町田町簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 上川田簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 川田簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 今井町簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 屋形原簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 岩本簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 上野簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 上久屋簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 白沢簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 利根北部簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 平原簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 穴原簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 根利簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 日影南郷簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 日向南郷簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 利根南部簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 清水町簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 坊坂簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 沼田市 奈良清水簡易水道事業Small water supply · 沼田市 | — | — | — | — | nd | — | raw water only |
| 渋川市 蟹谷戸簡易水道事業Small water supply · 渋川市 | — | — | — | — | — | nd | — |
| 渋川市 見滝簡易水道事業Small water supply · 渋川市 | — | — | — | — | — | nd | — |
| みどり市 東町簡易水道事業Small water supply · みどり市 | — | — | — | — | nd | — | raw water only |
| 上野村 中央簡易水道事業Small water supply · 上野村 | — | — | — | — | — | nd | — |
| 上野村 乙父簡易水道事業Small water supply · 上野村 | — | — | — | — | — | nd | — |
| 神流町簡易水道事業Small water supply · 神流町 | — | — | — | — | — | nd | — |
| 下仁田町 上小坂簡易水道事業Small water supply · 下仁田町 | — | — | — | — | — | planned | — |
| 下仁田町 四ツ家簡易水道事業Small water supply · 下仁田町 | — | — | — | — | — | planned | — |
| 南牧村 住吉簡易水道事業Small water supply · 南牧村 | — | — | — | — | — | planned | — |
| 南牧村 桧平簡易水道事業Small water supply · 南牧村 | — | — | — | — | nd | — | — |
| 南牧村 星尾簡易水道事業Small water supply · 南牧村 | — | — | — | — | — | planned | — |
| 南牧村 檜沢簡易水道事業Small water supply · 南牧村 | — | — | — | — | — | planned | — |
| 南牧村 勧能簡易水道事業Small water supply · 南牧村 | — | — | — | — | — | planned | — |
| 南牧村 砥沢簡易水道事業Small water supply · 南牧村 | — | — | — | — | — | planned | — |
| 南牧村 岩本簡易水道事業Small water supply · 南牧村 | — | — | — | — | — | planned | — |
| 南牧村 大塩沢簡易水道事業Small water supply · 南牧村 | — | — | — | — | — | planned | — |
| 南牧村 小沢簡易水道事業Small water supply · 南牧村 | — | — | — | — | nd | — | — |
| 南牧村 大仁田簡易水道事業Small water supply · 南牧村 | — | — | — | — | nd | — | — |
| 南牧村 大塩沢第二簡易水道事業Small water supply · 南牧村 | — | — | — | — | — | planned | — |
| 甘楽町 秋畑簡易水道事業Small water supply · 甘楽町 | — | — | — | — | nd | — | — |
| 甘楽町 那須簡易水道事業Small water supply · 甘楽町 | — | — | — | — | nd | — | — |
| 甘楽町 国峰簡易水道事業Small water supply · 甘楽町 | — | — | — | — | nd | — | — |
| 中之条町 中部簡易水道Small water supply · 中之条町 | — | — | — | — | — | nd | — |
| 中之条町 南部簡易水道Small water supply · 中之条町 | — | — | — | — | — | nd | — |
| 中之条町 世立簡易水道Small water supply · 中之条町 | — | — | — | — | — | nd | — |
| 中之条町 広池簡易水道Small water supply · 中之条町 | — | — | — | — | — | nd | — |
| 中之条町 和光原簡易水道Small water supply · 中之条町 | — | — | — | — | — | nd | — |
| 中之条町 小倉簡易水道Small water supply · 中之条町 | — | — | — | — | — | nd | — |
| 中之条町 田代原簡易水道Small water supply · 中之条町 | — | — | — | — | — | nd | — |
| 中之条町 京塚簡易水道Small water supply · 中之条町 | — | — | — | — | — | nd | — |
| 中之条町 中之条簡易水道Small water supply · 中之条町 | — | — | — | — | nd | — | — |
| 長野原町 北軽井沢簡易水道Small water supply · 長野原町 | — | — | — | — | nd | — | — |
| 長野原町 中部簡易水道Small water supply · 長野原町 | — | — | — | — | nd | — | — |
| 長野原町 東部簡易水道Small water supply · 長野原町 | — | — | — | — | nd | — | — |
| 白根高原羽根尾別荘分譲地水道事業Small water supply | — | — | — | — | nd | nd | raw water only |
| 長野原町 浅間高原水道Small water supply · 長野原町 | — | — | — | — | — | planned | — |
| ロイヤルパーク簡易水道事業Small water supply | — | — | — | — | — | nd | — |
| 嬬恋村 田代簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 古永井簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 干俣簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 上の貝簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 仁田沢簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 大笹簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 長井簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 大平簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 中原山梨簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 砂井簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 大前簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 西窪簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 袋倉簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 今井簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 石津簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 仙ノ入簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 門貝簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 三原簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 嬬恋村 万座簡易水道Small water supply · 嬬恋村 | — | — | — | — | — | nd | — |
| 日本興業奥軽井沢水道事業Small water supply | — | — | — | — | — | nd | — |
| 日本興業白樺台水道事業Small water supply | — | — | — | — | — | nd | — |
| 高山村 高山村簡易水道事業Small water supply · 高山村 | — | — | — | — | nd | — | — |
| 東吾妻町Small water supply · 東吾妻町 | — | — | — | nd | nd | nd | tap only |
| 本宿水道事業Small water supply | — | — | — | — | — | planned | — |
| 水神原水道事業Small water supply | — | — | — | — | — | planned | — |
| 清水水道事業Small water supply | — | — | — | — | — | nd | — |
| 五町田水道事業Small water supply | — | — | — | — | — | nd | — |
| 片品村 中央簡易水道事業Small water supply · 片品村 | — | — | — | — | nd | — | raw water only |
| 片品村 南部簡易水道事業Small water supply · 片品村 | — | — | — | — | — | nd | — |
| 片品村 北部簡易水道事業Small water supply · 片品村 | — | — | — | — | — | nd | — |
| 片品村 戸倉簡易水道事業Small water supply · 片品村 | — | — | — | — | — | nd | — |
| 片品村 栗生簡易水道事業Small water supply · 片品村 | — | — | — | — | — | nd | — |
| 片品村 針山簡易水道事業Small water supply · 片品村 | — | — | — | — | — | nd | — |
| 川場村 川場村簡易水道Small water supply · 川場村 | — | — | — | — | nd | — | — |
| 昭和村 南部簡易水道事業Small water supply · 昭和村 | — | — | — | nd | — | nd | tap only |
| 昭和村 中央簡易水道事業Small water supply · 昭和村 | — | — | — | nd | — | nd | tap only |
| 昭和村 北部簡易水道事業Small water supply · 昭和村 | — | — | — | nd | — | nd | tap only |
| 昭和村 東部簡易水道事業Small water supply · 昭和村 | — | — | — | nd | — | nd | tap only |
| 藤原簡易水道事業Small water supply | — | — | — | — | — | planned | — |
| 柳沼簡易水道事業Small water supply | — | — | — | — | — | nd | — |
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
- Shibukawa City’s annual maximums were 37, 50, 64, 23, 40 and 50 (FY2020–FY2025). In the November 2024 national table, the sampling points are the tap and raw water. The table does not show which one the listed values come from.
- According to MLIT’s case collection, values rose after the pump of Shibukawa Well No. 9 (渋川9号井) was replaced in November 2020 and the pumping rate increased, and in a July 2021 test the raw water (water before treatment at the plant) exceeded the provisional target value. The treated water (tap) is stated not to have exceeded it. The city reduced the pumping rate with a valve, and since FY2024 it has tested Well No. 9 and the treated water of the Arima supply area (有馬給水区域) five times a year. Raw water is not subject to the water supply standard.
- The next highest was the Takasaki City water utility (高崎市水道事業) at nd–33 (33 in FY2022), measured only in raw water. Maebashi City (前橋市) was nd–7. → How to read the national table
- Of the 139 rows in the table, 118 are small water supply systems. Private water supplies (for a facility) were tested at 57 of the 125 operators, and no exceedance 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
- How do you check PFAS in your local tap water? Reading the national tables and working out “what percent of the TDI”
- What happened in areas where high PFAS values were found in tap water? A timeline of Kibichuo, Tama, Okinawa and more
- Japan’s PFAS standard for tap water, “50 ng/L”: how was it set, and how does it differ from the U.S. and EU?
- Water filters and PFAS
Sources
- MLIT, “Case examples of PFOS and PFOA responses by water utilities to date” (November 29, 2024)
- 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.
This page lists levels published by national and local government bodies and facts from standards, assessments and papers. It does not judge whether tap water is good or bad or whether it affects health. Check the latest values and measures with your local water utility.