Routine water quality testing identified trace levels of selenium for the first time in the County of Maui Department of Water Supply’s Makawao water system.
The initial detection occurred in a sample collected on May 29, 2026, with follow-up testing from a sample collected on June 19 confirming selenium levels ranging from 3.7 to 4.9 micrograms per liter. DWS notified the Hawaiʻi Department of Health in accordance with state requirements.
According to the US Environmental Protection Agency and the Hawaiʻi Department of Health, the Maximum Contaminant Level for selenium in drinking water is 50 micrograms per liter. The levels detected in the Makawao water system are well below the drinking water standard.
“The amount of selenium detected is extremely small — about four parts per billion, or roughly four drops in 1 billion drops of water,” DWS Director John Stufflebean said. “Our dedicated water professionals work every day to monitor, maintain and care for our water system, and we remain committed to providing our community with safe, reliable water.”
Selenium is a naturally occurring mineral element found in soil, rocks and certain mineral deposits. Small amounts of selenium can enter drinking water sources through the natural erosion of mineral deposits.
DWS is required to notify DOH whenever selenium is detected for the first time in a public water system. DWS will continue working closely with DOH and monitoring the Makawao water system to maintain compliance with federal and state drinking water standards.
For more information, contact the County Department of Water Supply at 808-270-7550.
