The Hawai‘i State Department of Health has confirmed the presence of an organic chemical contaminant, polychlorinated biphenyls (PCBs), in a reservoir tank used in the Kaua‘i Department of Water, Kekaha-Waimea Drinking Water System, according to a DOH news release.
However, the DOH has determined drinking water served to the public from the tank was safe because samples collected from the water distribution system just after the tank did not contain PCBs.
The Kekaha-Waimea Water System serves a population of about 5,800 people on the westside of Kaua‘i. Samples collected in September at the Paua Valley Tank indicated that PCBs might be present in an oily sheen layer skimmed from the surface of the water. Water exits from the bottom of the tank and PCBs do not dissolve well in water. Although PCBs were not detected in the distribution system, the tank was taken out of service by Kaua‘i DOW as a precautionary measure.
The water samples were taken as part of a tank maintenance project by the Kaua‘i DOW, and an investigation of the source of the PCBs will be completed prior to cleaning and refurbishing the tank. The DOH will be working closely with the Kaua‘i DOW to ensure that adequate steps are taken to remove the source, or sources, of PCBs and thorough water quality testing is conducted before the Paua Valley Tank is placed back into service.
The concentration of total PCBs in an October sample from the surface of the tank was 13 micrograms per Liter, or parts per billion (ppb). Water tested from the pipe exiting the tank, leading to the distribution system, did not contain PCBs.
DOH also learned that scrapings from the interior coating of the tank wall in October were confirmed to contain PCBs. The range of total PCBs concentration for the three samples collected was 209 milligrams per kilogram (mg/Kg), or parts per million, to 283 mg/Kg.
The federal and state Maximum Contaminant Level for PCBs is 0.5 ppb at the compliance sampling point (exiting the tank). The standard is set to avoid health risks based on a lifetime of consuming water containing that level of contaminant. PCBs are a group of organic chemicals formerly used in the United States in hydraulic fluids, plasticizers, adhesives, fire retardants, and de-dusting agents. To date, the Kekaha-Waimea Water System continues to be in compliance with all federal and state standards for drinking water.
The Safe Drinking Water Branch of the Department of Health safeguards public health by protecting Hawaii’s drinking water sources (surface water and groundwater) from contamination and assures that owners and operators of public water systems provide safe drinking water to the community.