PFAS in tap water: Hokkaido

Levels by utility (PFOS + PFOA combined, ng/L)

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

• Values appear for only some utilities. The Furano City water utility (富良野市水道事業) had 28, 25 and 20 (FY2023–FY2025, tap and treatment plant outlet), the Furano City Yamabe urban area small water supply system (富良野市山部市街地区簡易水道) had 20, 21 and 16, and the Hidaka Town water utility (日高町水道事業) had 25 and 15 (FY2024 and FY2025). Hidaka Town’s values were measured only in raw water (water before treatment at the plant).
• The Sapporo City Waterworks Bureau (札幌市水道局) and the Hakodate City water utility (函館市水道事業) were nd (below the detection or quantification limit, too low to give a number) in every year they measured. The five bulk water suppliers (utilities that sell water wholesale to cities and towns) were also nd in every result.
• Of the 278 rows in the national table, 186 are small water supply systems (small systems serving 5,000 people or fewer), and 268 have a testing record. Many utilities had values listed for the first time from FY2024, so some have only a few years of data. → How to read the national table
• Private water supplies (for facilities such as company housing, hospitals and schools) were tested at 221 of the 526 operators in Hokkaido, and no exceedance of the provisional target value (50 ng/L) has been confirmed (through the end of August 2025).

Put it in terms of your own intake

Related explainers

• How do you check PFAS in your local tap water? Reading the national tables and working out “what percent of the TDI”
• 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?
• Do high PFAS values in rivers or groundwater mean high values in tap water? How guideline values differ from the tap water standard
• Water filters and PFAS

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.

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