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EPA SDWIS High-volume analyte Dense per-system load

Chlorine in Drinking Water

14.0 violations per affected system (199,108 across 14,191) - dense load (> 5.8 violations per affected system).

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EPA contaminant code: 0999

Total Violations
199,108
Systems Affected
14,191
Health-Based %
0.3%
Violations / System
14.0

Chlorine standing, high-volume SDWIS third

Chlorine sits in the upper third of this extract by raw violation count (199,108), so the national record is thick enough that system-level lists below are a sample of a much larger compliance trail rather than a near-complete inventory. Load is concentrated: 14.0 violations per affected system (dense load (> 5.8 violations per affected system)), which usually means repeat findings on the same PWSIDs rather than one-off detections spread thin. Health-based share is only 0.3% - almost all of this analyte's trail is monitoring/reporting rather than MCL exceedance. Among 157 indexable contaminants, this page is #9 by violation volume. Utilities listed below are ranked by cumulative violation count for this analyte; pair that with population served to gauge household exposure scale.

Nationwide similar contaminants

Nearest by violation volume

Consumer Confidence Rule (201,666) Total Haloacetic Acids (HAA5) (208,475) Combined Uranium (184,297) Arsenic (171,997)

Nearest by systems affected

1,1,2-Trichloroethane (14,235 systems) 1,2,4-Trichlorobenzene (14,097 systems) DICHLOROMETHANE (14,340 systems) o-Dichlorobenzene (14,344 systems)

Chlorine: mixed health vs monitoring split

0.3% health-based · 99.7% monitoring/reporting across 199,108 records.

Health-based (0.3%) Monitoring/Reporting (99.7%)

Most Affected Water Systems

System State Violations Population
Valley Elementary and Middle School NM 342 130
Circle H MHP NC 308 68
Chilili Water Users Assn NM 298 175
Walnut Park Estates OK 263 42
Hwy 7 East Water Assn OK 260 50
Pleasant Ridge Addition TX 253 195
Oak Hill Acres Mobile Home Subdivision TX 246 81
Follett Municipal Water System TX 239 412
Key Road Subdivision Water System TX 239 54
Farrar WSC TX 238 57
Lago Vista Water System TX 236 54
Timber Creek Addition TX 231 126
Centerline WSC TX 228 118
Brooksville OK 220 90
Surrey Hills OK 217 87
Seven Estates TX 216 189
Warren Road Subdivision Water Supply TX 215 195
Adrian Municipal Water System TX 214 129
Loma Escondida Water Association NM 210 89
South Midland County Water System TX 209 165
Green Hills Subdivision TX 204 55
Lazy Acres Trailer Park TX 202 105
Marlin Marina Water System TX 202 80
Derby Ing TX 201 174
Ojo Feliz Mdwca NM 200 63
City of Dell TX 198 245
Genesee Twp Water Authority PA 197 450
Eola WSC TX 195 165
Key Largo Utilities TX 191 105
Deanville WSC TX 189 2,850

Context: understanding water quality data · is my water safe?

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater

Disclaimer: This information is provided for informational purposes only and does not constitute professional advice. Data is sourced from the EPA Safe Drinking Water Information System (SDWIS). Consult a qualified professional before making decisions based on this data.

Read our methodology - how this data is sourced, computed, and verified.

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.