The Air Self-Defense Force Ashiya Airbase in Fukuoka Prefecture where PFAS levels were reportedly found to be 30 times the government’s provisional target (Mitsuya Nakanouchi)

Photo/Illutration Perfluoroalkyl and polyfluoroalkyl substances, collectively known as PFAS (The Asahi Shimbun)

As a new survey showed cancer-causing organic fluorine compounds exceeded limits in numerous private water systems across Japan, the Environment Ministry on Dec. 24 announced plans to boost water quality standards. 

The ministry plans to raise the current “provisional target” guidelines on PFAS compounds to a legally enforceable water quality standard starting in April 2026. 

The decision was approved at the ministry’s expert panel meeting held that day, which also reviewed nationwide survey findings showing provisional limits were exceeded in the private water systems across 11 of the nation’s 47 prefectures.

PFAS, or perfluoroalkyl and polyfluoroalkyl substances, are chemicals that contain bonds between carbon and fluorine.

The government currently sets a provisional target of keeping PFAS levels in tap water at 50 nanograms or lower per liter, measured as the combined concentrations of PFOS and PFOA, two of the most common types of PFAS. One nanogram is one-billionth of a gram.

The results of the nationwide survey on small-scale private water systems, such as those used in company housing and sanatoriums, were released at the meeting on Dec. 24.

Of around 8,000 systems, responses were received from 1,929. This means that inspections were confirmed for just more than 20 percent of those systems.

Among the responses, 42 cases in 10 prefectures were found to exceed the provisional target during the survey period from April 2020 to September 2024.

Later, two additional cases at Self-Defense Forces bases were discovered, bringing the total to 44 cases across 11 prefectures.

Among the private water systems that exceeded the provisional target, six were government-managed facilities.

Four are in Tokyo: Fuchu Prison, the Ground Self-Defense Force’s Camp Kodaira, the GSDF Camp Higashi-Tachikawa and the Air Self-Defense Force’s Fuchu Base.

The others are the ASDF Gifu Airbase in Gifu Prefecture and the ASDF Ashiya Airbase in Fukuoka Prefecture.

Of the 44 cases, 26 have already implemented measures such as switching to municipal water systems.

Fourteen cases have undertaken emergency responses including distributing bottled water, while four are planning to install water treatment facilities.

Upgrading to the water quality standard under the Water Supply Law will require stricter management compared to the current provisional target, which only requires suppliers to “make an effort” to conduct inspections.

Municipal water suppliers and other operators will be obliged to conduct water quality testing and take action if levels exceed the standard.

The government plans to proceed with the necessary steps, including consultation with the Cabinet Office’s Food Safety Commission. 

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