Japan's Environment Ministry has decided to require regular testing of tap water and set a legal standard for the concentration of PFAS chemicals, a group of organic fluorine compounds.

PFAS include PFOS and PFOA, which are considered potentially harmful.

The government set a provisional target in 2020 for the two chemicals at a total of 50 nanograms per liter for tap water.

The standard will remain the same as the current provisional target, which the government says is thought to cause no detrimental health effects. But there are currently no legal requirements for testing or other measures.

After higher concentrations of PFOS and PFOA were detected in a nationwide government survey, a panel of experts approved a policy to legally require the standard to be met.

This means local governments and water providers will be obligated to regularly test tap water. If the PFAS concentration exceeds the standard, they will have to take measures to improve the quality.

Water providers have said they will need time to respond so the policy is expected to be put into effect from April 2026.

The government conducted its first survey of dedicated water pipes for facilities such as universities and hospitals at 1,929 sites across the country over four years until September this year. It found that PFAS levels exceeded the provisional target at 42 locations.

PFAS levels higher than the provisional target were detected at two government facilities in subsequent testing.

The level detected at a Self-Defense Force facility in Fukuoka Prefecture was 30 times the provisional target.

Only 23 percent of all dedicated pipes have been tested due to the lack of a legal requirement.