PFAS in tap water: Kyoto 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

• The Fukuchiyama City Water and Sewerage Department reported 48 (FY2021), 47 and 75 (FY2023), then fell to 13 (FY2024) and nd (FY2025). The testing point is the tap. What was done to bring it down is not described in the national documents checked for this page.
• Kizugawa City Waterworks reported 26–30 ng/L for several years, then 61 ng/L in FY2025 (through the end of August). What happened next is not known from the public documents checked for this page.
• Seika Town Waterworks reported 63 (FY2020), 50, 30, 15, 39 and 27 ng/L. The 50 in FY2021 counts as “50 or below.” The testing points mix the tap, the treatment plant outlet and raw water (before treatment).
• Some suppliers have values in the 20s to 40s ng/L year after year, such as Uji City (宇治市) (18–49), Kyotanabe City (京田辺市) (30–35), Joyo City (城陽市) (17–39, raw water only), Nagaokakyo City (長岡京市) (20–29) and Ujitawara Town (宇治田原町) (16–35). In FY2024, only 8 of the 32 rows with a value were nd (below the quantification limit).
• Kyoto City Waterworks (京都市水道事業) reported 6–10 ng/L, and the Kyoto Prefectural Water Supply (京都府営水道, a bulk water supplier that sells water to municipalities) went from 13 (FY2020) to 5 (FY2025).
• Among private water supplies (for a facility, such as company housing or hospitals), 6 of the 45 operators tested in the prefecture exceeded the provisional target value. One of them is a national facility, the private water supply at Japan Ground Self-Defense Force Camp Okubo (陸上自衛隊大久保駐屯地), with 64 ng/L in raw water (handled for now with water purifiers as an emergency measure; removal equipment is planned).

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”
• 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

• 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; Table 6, private water supplies set up by the national government)
• Ministry of the Environment and MLIT, “Results of the Survey on PFOS and PFOA in Water Supply (follow-up survey)” (December 25, 2025)

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
• Osaka Prefecture
• Hyogo Prefecture
• Nara Prefecture
• Wakayama Prefecture