PlainWater
Contaminants →
EPA SDWIS High-volume analyte

Mercury in Drinking Water

13,488 public water systems carry at least one Mercury violation - wide footprint (> 8,691 systems).

Browse all SDWIS contaminants →

EPA contaminant code: 1035

Total Violations
49,728
Systems Affected
13,488
Health-Based %
0.6%
Violations / System
3.7

Mercury standing, high-volume SDWIS third

Mercury sits in the upper third of this extract by raw violation count (49,728), 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 sits mid-pack at 3.7 violations per affected system (mid load (≤ 5.8 violations per affected system)). Health-based share is only 0.6% - almost all of this analyte's trail is monitoring/reporting rather than MCL exceedance. Among 157 indexable contaminants, this page is #50 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

2,4-D (49,369) LASSO (49,306) Chromium (49,133) Cadmium (50,411)

Nearest by systems affected

Barium (13,488 systems) Fluoride (13,411 systems) Selenium (13,645 systems) Nitrite (13,772 systems)

Mercury: mixed health vs monitoring split

0.6% health-based · 99.4% monitoring/reporting across 49,728 records.

Health-based (0.6%) Monitoring/Reporting (99.4%)

Most Affected Water Systems

System State Violations Population
Ridgefield Public Works WA 114 20,967
PA American Audubon PA 77 8,200
Seven Estates TX 67 189
Coal Mountain Water WV 56 80
Mount Eagle Water Assoc PA 55 130
Ponce Urbano PR 53 111,926
Franklin Water Systems 3 TX 51 201
Hiawatha Water WV 51 63
Washington Township Mua NJ 49 48,000
Nottingham Manor M H Court PA 49 473
Shrewsbury Borough PA 49 4,727
Akhiok AK 43 90
Culvers Hill - North Webster IN 40 75
Westwood MHP NC 40 56
Pinnacle Water Association WV 40 85
Shiloh S/D NC 39 67
Whispering Pines MHP NC 39 305
Toxaway Point NC 38 79
Eastin CA 37 26
Happy Camper RV Park CO 37 40
South Bend Water Department WA 37 2,930
Creekside South Estates Metro District CO 36 160
Burlington City Of CO 36 3,720
Windmill Estates IL 36 65
Carmel Montessori Academy IL 36 40
Circle H MHP NC 35 68
Deerfield Park S/D NC 35 440
East Cherry Creek Valley WSD CO 34 66,130
Paint Brush Hills CO 34 4,994
Willow Springs MHP IN 34 25

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.