Guam tap water quality
5 community water systems serving 174,316 people.
Data: U.S. EPA · How we read the data · How we check it
PFAS: EPA's 2023–2025 testing. Lead: results from the last five years.
Water systems with PFAS above the federal limit
Based on EPA's UCMR 5 results (2023–2025) compared to the April 2024 limits, the way EPA compares them. Systems have until 2029 to comply. Largest first.
Guam PFAS report: chart, rankings and data to download →
Largest water systems in Guam
- Guam Waterworks Authority – Northern Water System139,207 people · Groundwater · GuamPFOA above limitAlso: PFOS above limit · PFHxS above limit · PFAS Hazard Index above limit
- U.S. Navy Water System12,780 people · Surface water · GuamTotal trihalomethanes (TTHM) violationAlso: Coliform bacteria violation · PFHxS detected
- Guam Waterworks Authority – Central Water System8,828 people · Purchased surface water · GuamColiform bacteria violation
- Andersen Air Force Base Water System7,700 people · Groundwater · GuamPFHxS detected
- Guam Waterworks Authority – Southern Water System5,801 people · Surface water · GuamColiform bacteria violation
Most health-based violations since 2016
- U.S. Navy Water System12,780 people · Surface water · GuamTotal trihalomethanes (TTHM) violationAlso: Coliform bacteria violation · PFHxS detected
- Guam Waterworks Authority – Central Water System8,828 people · Purchased surface water · GuamColiform bacteria violation
- Guam Waterworks Authority – Southern Water System5,801 people · Surface water · GuamColiform bacteria violation
All Guam utilities on this site
Every Guam system serving 50,000+ people or with PFAS above a federal limit, A to Z. Download all 5 systems as CSV.
Questions
Does Guam tap water have PFAS?
EPA tested 5 community water systems in Guam for 29 PFAS between 2023 and 2025. 3 had at least one regulated PFAS detected, and 1 had an entry-point average above a 2024 federal limit. Those 1 systems serve about 139,207 people (80% of people on community water in Guam). Systems have until 2029 to meet the limits.
How many Guam water systems have violations?
3 systems in Guam had at least one health-based violation since 2016 (4 violations in total).
Which Guam water systems are over the lead action level?
0 systems had a lead 90th percentile above the 15 ppb action level in their most recent results from the last five years. Lead depends on each home's pipes, so a test of your own tap is the only way to know your level.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.