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For Immediate Release
March 31, 2023

Board of Water Supply Confirms Low Level Detection of PFAS in Moanalua Wells

HONOLULU - The Board of Water Supply (BWS) has confirmed the low-level detection of perfluorobutanoic acid (PFBA) at its Moanalua Wells Pumping Station.  It also detected Perfluorooctanesulfonic acid (PFOS) in one sample out of four total samples collected and tested. 

The results are shown in the table below.  The BWS reported the findings to the Hawaii Department of Health (DOH) in accordance with Hawaii State Law.

On March 14, 2023, the U.S. Environmental Protection Agency (EPA) issued proposed National Primary Drinking Water Regulation maximum contaminant levels (MCLs) for Perfluorooctanoic acid (PFOA) and Perfluorooctanesulfonic acid (PFOS).  In addition, EPA also proposed a Hazard Index to determine the combined risk of four specific PFAS chemicals in drinking water at a site.  The Hazard Index is calculated by summing the ratios of each detected compound relative to its Health-Based Water Concentration.  The table below shows the PFAS detected and its amount in relation to EPA’s proposed standard and existing DOH environmental action levels (EALs)

According to DOH the amount of PFOS detected is above EPA’s interim lifetime health advisory of 0.02 ppt which could indicate a potential health risk over a lifetime of drinking water with this level of the chemical.  DOH has advised that those concerned may use a home filtration option to reduce PFAS.  Based on existing DOH environmental action level for PFBA, there would be no significant health concern for this chemical.

BWS detected these chemicals as part of its PFAS testing program.  Multiple samples were tested to confirm the finding and improvements in test methods and technology enables the detection of these very low levels.  The Moanalua Wells Pumping Station serves water to the Halawa Valley, Moanalua Valley and Mapunapuna.

PFAS are fluorinated organic chemicals that have been used extensively in consumer products such as carpets, clothing, fabrics for furniture, paper packaging for food, and other materials (e.g., cookware) designed to be waterproof, stain-resistant or non-stick.  They also have been used in fire-retarding foam.

Manager and Chief Engineer Ernest Lau stated, “We take our kuleana to provide safe drinking water to our community seriously and will continue to test for PFAS chemicals and monitor for any changes.”




Kathleen Pahinui 
Information Officer 
Honolulu Board of Water Supply
Phone: (808) 748-5319