PFAS in tap water: Hyogo Prefecture

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

• In June 2020, Takarazuka found 55 ng/L in raw water (deep wells) at the Kohama treatment plant (小浜浄水場) and 54 ng/L at a tap. It cut the intake from two wells by half and blended the water with water from other treatment plants, and since August 2024 it has stopped drawing from these two wells (MLIT case studies). The national table fell from 54 (FY2020) to 30 (FY2025).
• Nishiwaki reported 100 (FY2021), then 28, 32, 38 and 6 (FY2025). The testing point is the tap. What was done after the 100 reading is not described in the national documents checked for this page.
• The Tai Small Water Supply Association has risen from 28 (FY2023) to 44 and 69 (FY2025). The testing point is the tap. What was done next, and which municipality this water supply is in, are not known from the public documents checked for this page.
• Akashi City (明石市) has had raw water (a mix of river water and groundwater) above the provisional target value at the Akashigawa (明石川浄水場) and Toba (鳥羽浄水場) treatment plants, but not treated water (at taps). It was mainly PFOA, with only trace amounts of PFOS. The city brought levels down by replacing activated carbon sooner, adding powdered activated carbon, and storing river water in a reservoir after rain. It began switching to water from the Hanshin Water Supply Authority (阪神水道企業団) in FY2025 and plans to stop drawing from the Akashi River during FY2028 (case studies). The national table went from 48 (FY2020) to 6 (FY2025).
• The Hanshin Water Supply Authority (a bulk water supplier that sells water to cities) reported 6–40 ng/L (highest in FY2021), and Kobe City Waterworks (神戸市水道事業) nd–11 ng/L; for both, the testing points are the treatment plant outlet and raw water.
• Himeji City (姫路市) (10–30), Nishinomiya City (西宮市) (16–30), Kawanishi City (川西市) (19–34) and Miki City (三木市) (26–40), among others, also have years in the 20s to 30s ng/L. In FY2024, 21 of the 51 rows with a value were nd (below the quantification limit).
• Among private water supplies (for a facility, such as company housing or hospitals), 2 of the 82 operators tested in the prefecture exceeded the provisional target value. The facilities are not named in the national documents.

Timeline

Put it in terms of your own intake

Related explainers

• What happened in areas where high PFAS values were found in tap water? A timeline of Kibichuo, Tama, Okinawa and more
• How do you check PFAS in your local tap water? Reading the national tables and working out “what percent of the TDI”
• 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, “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)
• MLIT, “Cases of PFOS and PFOA responses by water suppliers to date” (November 29, 2024), Case 2: Akashi City and Case 10: Takarazuka City
• 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.

Other prefectures

• Mie Prefecture
• Shiga Prefecture
• Kyoto Prefecture
• Osaka Prefecture
• Nara Prefecture
• Wakayama Prefecture