Interactive tool
Harris vs Cook
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
1,292
427
Population Served
6,016,117
5,304,996
Systems with Violations
1,115
(86.3%)
301
(70.5%)
Violations
Total Violations
78,495
21,728
Health-Based Violations
MCL exceedances & treatment failures
5,075
(6.5%)
1,894
(8.7%)
Avg Violations / System
60.8
50.9
PFAS Contamination
Systems Tested for PFAS
261
114
PFAS Detected
256(98.1% rate)
13(11.4% rate)
Better relative to comparison
Worse relative to comparison
Equal / neutral
Harris County, Full Profile
Texas · 1,292 systems · 6,016,117 served
Cook County, Full Profile
Illinois · 427 systems · 5,304,996 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.