Low levels of two PFAS compounds have been detected in water samples from the Fort Shafter Wells Chlorinator on O‘ahu, Hawaii, according to the Hawaii Department of Health (DOH).

The Fort Shafter water system, operated by the U.S. Army Garrison Hawaii, reported detections of perfluorohexane sulfonic acid (PFHxS) and perfluorohexanoic acid (PFHxA) to the DOH on Sept. 23.

PFHxS concentrations ranged from nondetect to 2.28 nanograms per liter (ng/L), while PFHxA ranged from nondetect to 2.03 ng/L. The July 7, 2026, sample contained 2.28 ng/L of PFHxS and 2.03 ng/L of PFHxA. Both compounds were nondetect in an Aug. 19 sample.

The system previously detected 1.8 ng/L of PFHxS in an Aug. 8, 2023, sample. The DOH said the detections are unlikely to pose a public health risk.

The PFHxS concentrations are below the U.S. Environmental Protection Agency’s 10 ng/L maximum contaminant level (MCL). PFHxA does not have a federal MCL, although Hawaii’s current environmental action level for PFHxA in groundwater is 1,900 ng/L.

The Fort Shafter Wells Chlorinator serves the Fort Shafter area. The notification was issued under Hawaii Revised Statutes § 340E-24(b), which requires notification of previously detected contaminants in underground sources of drinking water or public water supplies.