On Wednesday, the Board of Water Supply announced that a drinking water sample from BWS Waihee Tunnel, which serves Windward Oahu from Kahana to Waimanalo, has tested positive for the presence of E. coli bacteria.

E. coli (Escherichia coli) is a coliform bacterium known as a fecal indicator because its presence indicates that water may be contaminated with human or animal feces. Pathogenic microorganisms in these wastes can cause diarrhea, headaches, or other symptoms, and may pose an elevated health risk for infants, young children, the elderly, and people with severely compromised immune systems, the BWS announcement said, noting that E. coli can also exist in soil.

Although most strains of E. coli are harmless, some can cause diarrhea, urinary tract infections or respiratory illness, according to the U.S. Centers for Disease Control.

The BWS statement said the water from the Waihee Tunnel is safe to drink because it is continuously disinfected before it reaches customers. The water was being disinfected on Monday, the day E.coli was detected.

The water board said it was providing public notice of the finding as required under the U.S. Environmental Protection Agency’s Ground Water Rule, which aims to reduce the potential risk of illness caused by microbial contamination in ground water. Under the rule, utilities must test their ground water when coliform bacteria are detected in any sample collected from the water system. If E. coli is found, the rule requires that the public be notified and that BWS take corrective actions.

BWS is consulting with the state Department of Health to determine the reason for the E.Coli presence and what actions to take.

Water from Waihee Tunnel has been tested on a monthly basis as part of a corrective action plan instilled in 2015, when routine testing detected E. coli in a water sample from the tunnel.

For more information, contact the BWS Water Quality Division at 748-5091 or the EPA Safe Drinking Water Hotline at 1(800) 426-4791.