PFAS in tap water: Wakayama Prefecture
For tap water in Wakayama Prefecture, the highest combined PFOS and PFOA value in FY2020–FY2025 (FY2025 through the end of August) was 32 ng/L in Iwade City (岩出市) in FY2023. No supplier exceeded 50 ng/L. The highest value was 27 in Kinokawa City (Kahoku) (紀の川市（河北）) in FY2024 (measured only in raw water = water before treatment) and 22 ng/L in Iwade in FY2025.
Levels by utility (PFOS + PFOA combined, ng/L)
| Utility | FY2020 | FY2021 | FY2022 | FY2023 | FY2024 | FY2025* | Sampled at |
|---|---|---|---|---|---|---|---|
| 和歌山市企業局Water supply · 和歌山市 | nd | 7 | 7 | 10 | 6 | 5 | plant outlet and raw |
| 田辺市水道事業Water supply · 田辺市Also buys from: 白浜町用水供給, 上富田町用水供給 | — | — | nd | — | — | — | tap only |
| 橋本市水道事業Water supply · 橋本市 | nd | nd | nd | nd | nd | — | tap and raw |
| 海南市(海南)Water supply · 海南市 | nd | 7 | 5 | 7 | 6 | 5 | tap only |
| 海南市(下津)Water supply · 海南市buys all its water | nd | nd | nd | nd | nd | nd | tap only |
| 有田市Water supply · 有田市 | nd | nd | nd | nd | nd | nd | tap only |
| 御坊市Water supply · 御坊市 | nd | nd | nd | nd | nd | nd | raw water only |
| 新宮市Water supply · 新宮市 | — | nd | nd | nd | nd | nd | plant outlet only |
| 紀の川市（河北）Water supply · 紀の川市 | — | 19 | 12 | 29 | 27 | — | raw water only |
| 紀の川市（河南）Water supply · 紀の川市 | — | 11 | 14 | 12 | 11 | — | raw water only |
| 岩出市Water supply · 岩出市 | 12 | 11 | 23 | 32 | 19 | 22 | tap and raw |
| かつらぎ町Water supply · かつらぎ町 | — | nd | 7 | nd | 5 | — | raw water only |
| 湯浅町Water supply · 湯浅町 | — | 10 | 13 | 6 | 9 | 9 | 原水 |
| 有田川町Water supply · 有田川町 | — | nd | nd | nd | nd | — | raw water only |
| 美浜町Water supply · 美浜町buys all its water | — | nd | nd | nd | nd | — | tap only |
| 日高町Water supply · 日高町buys all its water | — | nd | nd | nd | nd | — | plant outlet only |
| 由良町Water supply · 由良町 | — | nd | 25 | nd | nd | — | raw water only |
| 印南町Water supply · 印南町 | — | nd | nd | nd | nd | — | tap and plant outlet |
| みなべ町Water supply · みなべ町 | 10 | 9 | 6 | 10 | 5 | 8 | raw water only |
| 日高川町Water supply · 日高川町 | — | nd | nd | nd | nd | nd | raw water only |
| 白浜町Water supply · 白浜町 | — | nd | nd | nd | nd | — | tap only |
| 上富田町Water supply · 上富田町 | — | nd | nd | nd | nd | nd | raw water only |
| すさみ町Water supply · すさみ町 | — | nd | nd | nd | nd | nd | raw water only |
| 那智勝浦町Water supply · 那智勝浦町 | — | nd | nd | nd | nd | nd | raw water only |
| 串本町Water supply · 串本町 | — | nd | nd | nd | nd | — | tap and raw |
| 白浜町用水供給Bulk supplier · 白浜町Supplies: 田辺市 | — | nd | nd | nd | nd | — | plant outlet only |
| 上富田町用水供給Bulk supplier · 上富田町Supplies: 田辺市 | — | nd | nd | nd | nd | nd | raw water only |
| 新宮市三津ノ 簡水Small water supply · 新宮市 | — | — | — | — | — | nd | — |
| 新宮市宮井 簡水Small water supply · 新宮市 | — | — | — | — | — | nd | — |
| 新宮市敷屋 簡水Small water supply · 新宮市 | — | — | — | — | — | nd | — |
| 新宮市小口 簡水Small water supply · 新宮市 | — | — | — | — | — | nd | — |
| 新宮市西高田 簡水Small water supply · 新宮市 | — | — | — | — | — | nd | — |
| 紀美野町西部 簡水Small water supply · 紀美野町 | nd | nd | nd | nd | nd | — | tap only |
| 紀美野町中田 簡水Small water supply · 紀美野町 | nd | nd | nd | nd | nd | — | tap only |
| 紀美野町河北 簡水Small water supply · 紀美野町 | nd | nd | nd | nd | nd | — | tap only |
| 紀美野町河南 簡水Small water supply · 紀美野町 | nd | nd | nd | nd | nd | — | tap only |
| 紀美野町美里 簡水Small water supply · 紀美野町 | nd | nd | nd | nd | nd | — | tap only |
| 紀美野町毛原 簡水Small water supply · 紀美野町 | nd | nd | nd | nd | nd | — | tap only |
| 紀美野町長谷宮 簡水Small water supply · 紀美野町 | nd | nd | nd | nd | nd | — | tap only |
| かつらぎ町広口 簡水Small water supply · かつらぎ町 | — | — | — | — | nd | — | — |
| かつらぎ町渋田 簡水Small water supply · かつらぎ町 | — | — | — | — | nd | — | — |
| かつらぎ町見好東部 簡水Small water supply · かつらぎ町 | — | — | — | — | nd | — | — |
| かつらぎ町教良寺 簡水Small water supply · かつらぎ町 | — | — | — | — | nd | — | — |
| かつらぎ町御所 簡水Small water supply · かつらぎ町 | — | — | — | — | nd | — | — |
| かつらぎ町天野 簡水Small water supply · かつらぎ町 | — | — | — | — | nd | — | — |
| かつらぎ町新城 簡水Small water supply · かつらぎ町 | — | — | — | — | nd | — | — |
| かつらぎ町花園梁瀬 簡水Small water supply · かつらぎ町 | — | — | — | — | nd | — | — |
| 九度山町九度山簡水Small water supply · 九度山町 | — | 7 | nd | nd | 5 | nd | raw water only |
| 高野町高野山 簡水Small water supply · 高野町 | — | — | — | — | — | planned | — |
| 高野町富貴 簡水Small water supply · 高野町 | — | — | — | — | — | planned | — |
| 広川町広川 簡水Small water supply · 広川町 | — | 5 | nd | 7 | 6 | — | tap only |
| 有田川町金屋 簡水Small water supply · 有田川町 | — | nd | nd | nd | nd | — | raw water only |
| 有田川町金屋北 簡水Small water supply · 有田川町 | — | nd | nd | nd | nd | — | raw water only |
| 有田川町吉原 簡水Small water supply · 有田川町 | — | nd | nd | nd | nd | — | raw water only |
| 有田川町釜中 簡水Small water supply · 有田川町 | — | nd | nd | nd | nd | — | raw water only |
| 有田川町岩倉 簡水Small water supply · 有田川町 | — | nd | nd | nd | nd | — | raw water only |
| 有田川町西ヶ峯 簡水Small water supply · 有田川町 | — | nd | nd | nd | nd | — | raw water only |
| 有田川町早月 簡水Small water supply · 有田川町 | — | nd | nd | nd | nd | — | raw water only |
| 有田川町五西月北 簡水Small water supply · 有田川町 | — | nd | nd | nd | nd | — | raw water only |
| 有田川町清水 簡水Small water supply · 有田川町 | — | nd | nd | nd | nd | — | raw water only |
| 白浜町市江 簡水Small water supply · 白浜町 | — | nd | nd | nd | nd | — | tap only |
| 白浜町田野井 簡水Small water supply · 白浜町 | — | nd | nd | nd | nd | — | tap only |
| 白浜町口ヶ谷 簡水Small water supply · 白浜町 | — | nd | nd | nd | nd | — | tap only |
| 白浜町安居 簡水Small water supply · 白浜町 | — | nd | nd | nd | nd | — | tap only |
| 白浜町久木 簡水Small water supply · 白浜町 | — | nd | nd | nd | nd | — | tap only |
| 白浜町玉伝 簡水Small water supply · 白浜町 | — | nd | nd | nd | nd | — | tap only |
| 白浜町市鹿野 簡水Small water supply · 白浜町 | — | nd | nd | nd | nd | — | tap only |
| 白浜町上滝 簡水Small water supply · 白浜町 | — | nd | nd | nd | nd | — | tap only |
| 白浜町城 簡水Small water supply · 白浜町 | — | nd | nd | nd | nd | — | tap only |
| すさみ町江住 簡水Small water supply · すさみ町 | — | — | — | — | — | nd | — |
| すさみ町佐本 簡水Small water supply · すさみ町 | — | — | — | — | — | nd | — |
| すさみ町太間川 簡水Small water supply · すさみ町 | — | — | — | — | — | nd | — |
| すさみ町口和深 簡水Small water supply · すさみ町 | — | — | — | — | — | nd | — |
| すさみ町立野 簡水Small water supply · すさみ町 | — | — | — | — | — | nd | — |
| 古座川町古座川 簡水Small water supply · 古座川町 | nd | nd | nd | nd | nd | nd | raw water only |
| 太地町太地 簡水Small water supply · 太地町 | — | nd | nd | nd | nd | — | raw water only |
| 太地町夏山 簡水Small water supply · 太地町 | — | — | — | — | nd | — | tap only |
| 北山村北山 簡水Small water supply · 北山村 | — | — | — | — | — | 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
- Iwade’s testing points are the tap and raw water. The Wakayama City Public Enterprise Bureau (和歌山市企業局) reported nd–10 ng/L (testing points: treatment plant outlet and raw water).
- In FY2024, 54 of the 64 rows with a value were nd (below the quantification limit). For FY2025 (through the end of August), 27 of the 78 rows in the table have a value (another 2 rows say “to be tested within the fiscal year”).
- Among private water supplies (for a facility, such as company housing or hospitals), none of the 12 tested in the prefecture was found to exceed the provisional target value (50 ng/L) (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, “Survey on PFOS and PFOA in Water Supply,” follow-up survey: list of results (published December 25, 2025)
- Ministry of the Environment and MLIT, list of results (published November 29, 2024; testing point column)
- Same follow-up survey, attachment (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.