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Interim Enhanced Surface Water Treatment Rule in U.S. Drinking Water

Health-based violation data for Interim Enhanced Surface Water Treatment Rule from EPA Safe Drinking Water Information System (SDWIS). Covers all community water systems with violations on record.

Interim Enhanced Surface Water Treatment Rule has been found in violation of EPA standards in 968 water systems across 48 states, with 8,860 total health-based violations recorded. The most affected states are Oklahoma, Texas, Alaska.

Health-Based Violation Records
8,860
Water Systems Affected
968
States Affected
48

Interim Enhanced Surface Water Treatment Rule is regulated under the EPA Safe Drinking Water Act, which sets enforceable Maximum Contaminant Levels (MCLs) and associated treatment technique requirements for public water systems. The EPA Safe Drinking Water Information System (SDWIS) tracks every recorded violation nationwide and links it back to the specific public water system (PWSID), violation type, and begin date.

Across the United States, PlainEnviro's joined extract contains 8,860 health-based violation records carrying Interim Enhanced Surface Water Treatment Rule (EPA code 0300) across 968 active community water systems in 48 states. Raw record counts are highest in Oklahoma, Texas, Alaska, with Oklahoma accounting for 1,417 records across 81 systems. Health-effect prose is shown only when the official ECHO substance name matches a verified topic; otherwise the portal stays silent rather than inventing guidance.

A health-based violation does not mean residents were necessarily harmed, it means the contaminant exceeded the federal MCL in a compliance sample, triggering notification and remediation requirements. States and utilities maintain primary enforcement responsibility. To check the status of a specific water system, request its most recent Consumer Confidence Report or consult the EPA's Drinking Water Watch portal for the corresponding state.

Violations by State

States ranked by number of health-based violations for Interim Enhanced Surface Water Treatment Rule.

# State Violations Systems Affected
1 Oklahoma 1,417 81
2 Texas 1,062 86
3 Alaska 532 37
4 Puerto Rico 530 35
5 Louisiana 379 18
6 Colorado 308 56
7 Oregon 271 22
8 West Virginia 267 37
9 Arizona 177 15
10 Missouri 163 12
11 Illinois 153 40
12 New Mexico 149 9
13 California 132 30
14 Kansas 109 15
15 Idaho 90 9
16 New York 88 28
17 Pennsylvania 85 22
18 Minnesota 80 4
19 Kentucky 78 18
20 Tennessee 78 15
21 Arkansas 75 17
22 Ohio 60 19
23 North Carolina 55 15
24 Indiana 29 7
25 South Dakota 25 3
26 Washington 23 5
27 Iowa 22 3
28 Mississippi 22 1
29 Montana 22 5
30 Wyoming 22 7
31 Florida 19 3
32 New Jersey 19 7
33 South Carolina 17 6
34 Maine 15 4
35 Michigan 10 5
36 Massachusetts 9 4
37 Maryland 8 4
38 Nebraska 7 2
39 New Hampshire 6 2
40 Utah 5 1
41 Vermont 4 1
42 Alabama 3 1
43 Connecticut 3 2
44 Rhode Island 3 1
45 Georgia 2 1
46 Delaware 1 1
47 Nevada 1 1
48 Virginia 1 1

Most Affected Water Systems

Top 50 water systems by number of Interim Enhanced Surface Water Treatment Rule health-based violations.

Water System State Violations
METROPOLITANO PR 166
CITY OF NOME TX 165
WEWOKA PUBLIC WORKS AUTHORITY OK 164
CITY OF ROSE CITY TX 155
UNALAKLEET CITY WATER SUPPLY AK 152
SARDIS LAKE WATER AUTHORITY OK 151
LONDON WATER CO-OP OR 134
WAGONER CO. RWD #2 OK 124
CITY OF FRANKLIN WATER SUPPLY LA 119
WARDENSVILLE, TOWN OF WV 105
CHEROKEE CO. RWD #1 (FT GIBSON) OK 85
CITY OF RIO HONDO TX 74
MAYSVILLE PWS MO 70
PONCE URBANO PR 58
HOMINY OK 57
BUCKLAND WATER SYSTEM AK 56
TOWN OF NEWELLTON WATER SYSTEM LA 56
MAYSVILLE OK 55
VALLECITOS MDWCA NM 52
GRAYLING WATER SYSTEM AK 51
PENDLETON WATER ASSOCIATION LA 50
KICKAPOO TRIBAL WATERWORKS KS 49
DIVIDE SOUTH CO 47
CHICKASHA MUNICIPAL AUTHORITY OK 47
CLEARWATER WATER DIST ID 46
GORE PWA OK 45
THE CLIFFS TX 44
WAURIKA PUBLIC WORKS AUTHORITY OK 41
CITY OF SHREVEPORT WATER SYSTEM LA 40
Thief River Falls MN 40
EL YUNQUE PR 40
BEGGS OK 38
NATIVE VILLAGE OF SLEETMUTE AK 36
MONROE CITY PWS MO 36
HOLDENVILLE OK 36
BARNSDALL OK 36
GRAND PORTAGE MN 35
ZAPATA COUNTY SAN YGNACIO AND RAMIRENO TX 35
EUFAULA PWA OK 34
HASKELL CO. WATER COMPANY OK 33
SLC WSC TX 33
EPCOR - LAKESIDE AZ 32
COMERIO URBANO PR 32
Yurok - McCoy - Kenek CA 30
INTRACOASTAL WATER SYSTEM WEST LA 30
COTTO LAUREL PR 30
CITY OF ZAVALLA TX 28
WELLTON TOWN OF AZ 27
CITY OF MANSFIELD WATER SYSTEM LA 27
CIMARRON WATER SYSTEM NM 27

Frequently Asked Questions

Is Interim Enhanced Surface Water Treatment Rule in my water?

Interim Enhanced Surface Water Treatment Rule has been detected in violation of EPA health standards in 968 water systems across 48 states. To check your specific utility, look up your annual Consumer Confidence Report (CCR) - water systems are required to disclose all violations.

How many water systems have Interim Enhanced Surface Water Treatment Rule violations?

EPA SDWIS records show 968 community water systems with health-based Interim Enhanced Surface Water Treatment Rule violations, totaling 8,860 violations. These represent cases where the contaminant exceeded the EPA Maximum Contaminant Level (MCL).

Which states have the most Interim Enhanced Surface Water Treatment Rule violations?

The states with the most Interim Enhanced Surface Water Treatment Rule violations are: Oklahoma (1,417 violations), Texas (1,062 violations), Alaska (532 violations), Puerto Rico (530 violations), Louisiana (379 violations).

Explore More

Water Quality Home → All Contaminants → Browse by State →

About This Data

Violation data is from the EPA Safe Drinking Water Information System (SDWIS). Only health-based violations are shown, these include Maximum Contaminant Level (MCL) and Treatment Technique (TT) violations. Monitoring and reporting violations are excluded. Data may not reflect the most current enforcement actions.

Source: U.S. Environmental Protection Agency, SDWIS Federal Reporting Services

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

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Data sourced from the U.S. Environmental Protection Agency (EPA). See our methodology for details. Retrieved and formatted by PlainEnviro