Trace levels of selenium detected in Lahaina Water System; amounts far below safety limits

Trace levels of selenium have been detected for the first time in water samples during routine water testing of the Lahaina Water System, which services Lahaina, Honokōwai and Nāpili, according to the County of Maui Department of Water Supply (DWS).

Samples collected Sept. 29 and Oct. 23, 2025, at the point where treated water enters the distribution system detected selenium levels ranging from 6 micrograms to 7.4 micrograms per liter. According to the U.S. Environmental Protection Agency and the Hawai'i Department of Health (DOH), the Maximum Contaminant Level for selenium in drinking water is 50 micrograms per liter -- the highest concentration considered safe for lifelong consumption based on known health risks.

"The levels of selenium detected are very small and far below safety limits," DWS Director John Stufflebean said. "Our community's health and well-being are at the heart of everything we do, and we will continue monitoring water quality to ensure it remains safe for daily use."

Selenium is a naturally occurring mineral found in soil, rocks and certain mineral deposits. It can enter drinking water resources naturally through erosion, and human activities, such as irrigated agriculture, can also contribute to its presence.

By law, DWS is required to notify DOH if any selenium is initially discovered within its sample. Once selenium detection has been assessed by DOH, DOH is required to release detection information.

For more information, contact DWS at (808) 270-7550.