Interactive tool
Maricopa vs San Diego
Put any two U.S. counties side by side on drinking-water violations, PFAS detection, and system coverage, straight from EPA SDWIS and UCMR5 testing.
- 3,254
- Counties available
- 63
- States & territories
- 142,471
- Water systems covered
According to the EPA's Safe Drinking Water Information System (SDWIS) and UCMR5 testing program, every figure in this comparison is pulled directly from official public water-system records. See our methodology for how violations and PFAS detections are counted.
Choose Counties to Compare
Water Systems
Water Systems
215
197
Population Served
4,392,896
3,744,323
Systems with Violations
209
(97.2%)
185
(93.9%)
Violations
Total Violations
30,745
4,832
Health-Based Violations
MCL exceedances & treatment failures
1,092
(3.6%)
1,612
(33.4%)
Avg Violations / System
143.0
24.5
PFAS Contamination
Systems Tested for PFAS
42
26
PFAS Detected
42(100.0% rate)
26(100.0% rate)
Better relative to comparison
Worse relative to comparison
Equal / neutral
Maricopa County, Full Profile
Arizona · 215 systems · 4,392,896 served
San Diego County, Full Profile
California · 197 systems · 3,744,323 served
Data source: EPA Safe Drinking Water Information System (SDWIS) and UCMR5 PFAS monitoring program.
Teal = better (fewer violations / more systems),
amber = worse (more violations / fewer systems).
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.