PFAS Detected in Kaʻamilo Wells Pumping Station

Posted on May 11, 2023 in Newsroom

HONOLULU – Chemicals known as PFAS (perfluoroalkyl and polyfluoroalkyl substances) have been detected for the first time in water samples collected at Ka‘amilo Wells Pumping Station, which is part of the Honolulu Board of Water Supply’s (BWS) Honolulu-Windward-Pearl Harbor water system (Public Water System HI0000331) and serves the central area of the island of O‘ahu.

All detected PFAS levels are below the Environmental Protection Agency’s (EPA) proposed Maximum Contaminant Levels (MCL). The Hazard Index of 0.35 is below EPA’s proposed 1.0 compliance threshold. Based on current information, a significant health risk is not expected for the chemicals that were detected.

PFAS at Ka‘amilo Wells were confirmed in lab reports dated April 7, 2023, April 14, 2023, and April 20, 2023. BWS notified the Hawaiʻi State Department of Health (DOH) of the results through a single submittal on April 26, 2023.

Detected levels of PFAS in Ka‘amilo Wells are listed in the table below.

PFAS ChemicalPFAS Chemical AbbreviationDetected levels (ng/L) 1EPA Proposed MCL (ng/L) 1, 2
Perfluorobutanesulfonic acidPFBSND3 – 2.1see note 4
Perfluorohexanoic acid PFHxA2.1 – 2.6
Perfluorohexanesulfonic acidPFHxS2.3 – 3.1see note 4
Perfluorooctanoic acid PFOA2.5 – 2.84.0
Perfluorooctanesulfonic acid PFOS2.9 – 3.0 4.0
Perfluoropentanoic acid PFPeA2.2 – 2.4

ng/L = nanogram per liter = parts per trillion (ppt)

Boxes left blank indicate that a level has not been set for that chemical.

ND = non-detect/not detected

This contaminant is considered in the proposed Hazard Index calculation.  

According to the EPA, PFAS, which have been used since the 1940’s, 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 are also a component of fire-fighting foam and have many industrial uses.

For more information on PFAS, please see or Users may also contact their water purveyor.

This press release is issued in accordance with Hawaii Revised Statutes (HRS) Section 340E24(b), which requires the drinking water system to notify DOH of any previously undetected contaminant within seven (7) days of detecting the contaminant. DOH then has fourteen (14) days to notify the public through the media.

Acronyms and Definitions

DOH – Hawai‘i Department of Health, responsible for regulation and oversight of impacts to the environment and health of the people in Hawaii.  This includes regulated drinking water systems.

EPA – United States Environmental Protection Agency responsible for the protection of human health and the environment on a national level.

HRS – Hawai‘i Revised Statutes are laws enacted by the Hawaii State legislature.

Hazard Index – A cumulative health risk to be considered when multiple compounds are present even if individual MCLs or EALs are met.  The Health Index is the sum of the ratios of the respective contaminants.  The proposed EPA requirement is to be less than 1.0 (unitless) to be in compliance.

MCL – Maximum Contaminant Level, set by EPA, is the highest level of a contaminant that is allowed in drinking water.  Proposed MCLs are not enforceable.  On March 14, 2023, EPA issued proposed MCLs for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) and Maximum Contaminant Level Goals (MCLGs) for four additional PFAS compounds.  Final MCLs are anticipated in late 2023, at which time these values would become enforceable legal limits and public water systems would be required to test for these chemicals.

PFAS – Perfluoroalkyl and Polyfluoroalkyl substances, fluorinated organic chemicals that have been used extensively since the 1940s.

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