For the third week in a row, tests show no detection of dieldrin at Guam Waterworks Authority’s (GWA) Y-15 well in Yigo, confirming that the interim treatment system has effectively removed the contaminant. Laboratory analysis from three consecutive rounds of testing reported “non-detect” results, validating the success of the granular activated carbon (GAC) filtration system commissioned on Oct. 10. The EPA-approved system is designed to remove contaminants such as dieldrin and PFAS from drinking water.
Weekly sampling continues under the direction of the Guam Environmental Protection Agency (Guam EPA) to ensure compliance with the interim action level (IAL) for dieldrin. A fourth round of sampling conducted Oct. 30 is pending results. If the next test also yields non-detect findings, GWA will request that Guam EPA lift the “Do Not Drink Without Treatment” advisory affecting Yigo and Santa Rosa area customers. Testing and analysis are conducted by Eurofins Eaton Analytical, an EPA-certified laboratory in California.
Once four consecutive weeks of clean results are confirmed, GWA will continue operating the interim GAC system while developing a permanent treatment facility expected in 2026. The agency will perform monthly sampling and share results publicly at guamwatersafety.com. GWA reports that most of its 124 sampling locations across the island show dieldrin levels below IALs, with only one well—D-17 in Dededo—remaining offline since July due to elevated levels.
GWA’s customer service call center has returned to normal operating hours, with residents encouraged to contact 671-647-7800 for assistance or visit gwa.custhelp.com for inquiries. Guam EPA continues to provide a hotline at 671-888-4342 for health and water safety concerns. Both agencies reaffirm their commitment to transparency and to ensuring Guam’s drinking water remains safe.