The government has asked water providers across the country to check for PFAS, people familiar with the matter said Monday.

Some 12,000 water providers have been given until the end of September to report on potential water contamination with PFAS, or perfluoroalkyl and polyfluoroalkyl substances — chemical compounds suspected to be carcinogenic. The request was made by the environment and infrastructure ministries on May 29.

The government has a provisional target of keeping PFAS levels in tap water at 50 nanograms or lower per liter. Tests for PFAS are conducted by water providers on a voluntary basis under the water supply law.

The nationwide survey comes after a concentration of PFAS equivalent to 28 times the national standard was detected at a water purification plant in Kibichuo, Okayama Prefecture, in October last year.

Based on the results of the survey, the government plans to consider reviewing the target and how PFAS are treated under the water supply law.

PFAS, which have properties to repel water and oil, have been once used in a wide variety of products including firefighting foams and coatings for frying pans.

Japan had banned production and imports of two key PFAS compounds by 2021. But high concentrations of PFAS have been detected in public water near U.S. military bases and chemical plants in the country.