Gwa Central Water System

Water Quality Snapshot: Gwa Central Water System

Gwa Central Water System is a state-owned community water system that delivers drinking water to 21,398 residents in Mangilao, Guam (Guam County) through 3,295 service connections. Its water is drawn from surface water sources. EPA's Safe Drinking Water Information System records 106 total violations for this system , of which 63 (59%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 31 monitoring and reporting violations are on file. The most recent violation on record dates to 2022.

The most frequently cited contaminant at this system is TTHM, recorded in 34 violations (MCL, health-based). This system was sampled under EPA's UCMR5 PFAS monitoring program and no PFAS compounds were detected above the minimum reporting level.

Across Guam, EPA tracks 8 public water systems serving 327,417 people, with 203 cumulative violations and 94 health-based violations on record. About 100% of systems in the state carry at least one violation, and state-wide the average per system is 25.4 violations. Statewide, 3 of 5 UCMR5-tested systems have reported PFAS detections (60%).

Gwa Central Water System's 106 violations sit above the Guam average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.