Water system rankings
National comparisons computed across every active public water system in EPA SDWIS records.
Dataset updated . Source: EPA SDWIS/ECHO, refreshed quarterly.
Largest U.S. water systems
The 100 largest active public water systems by population served.
States by water system count
All 50 states + DC ranked by active public water systems and population coverage.
Groundwater vs. surface water
Which states rely on groundwater and which on surface water, by share of systems.