Guam
Water quality data from the EPA Safe Drinking Water Information System
Lead Risk: Caution
Water Systems
21
Active public water systems
Population Served
314.7K
Residents with piped water
Lead Violations
0
Systems exceeding 15 ppb
Copper Violations
3
Lead & Copper Rule
Average Lead Level
2.24 ppb
EPA Action Level: 15 ppb
MCLG (health goal): 0 ppb
0 ppbAction Level: 15 ppb
Average across 8 systems with reported lead data.
Violations Detected
3 water systems in Guam have reported violations under the Lead and Copper Rule. These utilities are required to notify customers and take corrective action.
0 lead violations3 copper violations
Water Systems: Highest Lead Levels
| System Name | City | Population | Lead Level | Status | Sample Date |
|---|---|---|---|---|---|
| TAMUNING | 138,336 | 2.30 ppb | OK | 2025-06-30 | |
| MANGILAO | 139,207 | 1.70 ppb | OK | 2025-12-31 | |
| MANGILAO | 21,398 | 0.77 ppb | OK | 2025-12-31 |
Showing top 3 of 7 systems with lead data. Action level: 15 ppb.
Systems With Active Violations
These water systems have exceeded EPA limits and must take corrective action.
GWA NORTHERN WATER SYSTEM
MANGILAO · Pop. 139,207
Copper
Lead: 1.70 ppb (2025-12-31)
GWA CENTRAL WATER SYSTEM
MANGILAO · Pop. 21,398
Copper
Lead: 0.77 ppb (2025-12-31)
Water Source Types
Groundwater13 (72%)
Purchased Surface Water2 (11%)
Purchased Groundwater2 (11%)
Surface Water1 (6%)
Data source:EPA Safe Drinking Water Information System (SDWIS), Lead and Copper Rule monitoring data. Lead levels represent 90th percentile results from the most recent monitoring period. Violations indicate exceedances of EPA action levels requiring corrective action. This tool is for informational purposes only and does not replace your utility's official Consumer Confidence Report.