Surface Water Treatment Rule (SWTR) in drinking water
1,357 active public water systems in 40 states had a Surface Water Treatment Rule (SWTR) violation in the past three years, and 341 had one in the latest quarter of EPA's data.
You are on Tapcensus, an independent guide to the EPA compliance records of every public water system in the United States. This page explains Surface Water Treatment Rule (SWTR) and lists the water systems whose records include a related violation. It does not show measured levels.
Is Surface Water Treatment Rule (SWTR) in the records for your water system?
Enter a ZIP code, town, or street address to see the water systems that serve your area, their status, and which rules and contaminants appear in their violations.
Enter a ZIP code, town, or street address.
What it is and where it comes from
All systems using surface water (rivers, lakes, reservoirs) or groundwater under surface influence (GWUDI) must filter and disinfect. Treatment technique violations mean the system failed to maintain adequate disinfectant residual, exceeded turbidity limits, or lacked required permits. Snowmelt and storm events can raise turbidity and pathogen loads in surface water.
Health effects
Without proper filtration/disinfection: Giardia lamblia (severe diarrhea, cramping), Cryptosporidium (life-threatening for immunocompromised individuals), viruses (hepatitis A, norovirus). Turbidity itself is not a health risk but can shield pathogens from disinfection.
The standard and what a violation means
EPA limit: Treatment technique: turbidity ≤0.3 NTU in 95% of monthly samples; detectable disinfectant residual in 95% of distribution samples.
Water systems with a Surface Water Treatment Rule (SWTR) violation, by state
Active public water systems that reported at least one related violation to EPA in the past three years. Each state links to the list of its affected systems.
| State | Systems with violations, 3 yr | Share of active systems | In violation, latest quarter |
|---|---|---|---|
| Colorado | 284 | 13% | 50 |
| Pennsylvania | 153 | 2% | 31 |
| Alaska | 141 | 11% | 57 |
| Oregon | 139 | 5% | 46 |
| West Virginia | 76 | 10% | 18 |
| California | 56 | 1% | 28 |
| New Jersey | 55 | 2% | 6 |
| Arizona | 45 | 3% | 9 |
| Texas | 42 | 1% | 7 |
| Oklahoma | 41 | 3% | 4 |
| Wyoming | 31 | 4% | 7 |
| Montana | 30 | 1% | 13 |
| Washington | 29 | 1% | 10 |
| New Mexico | 25 | 2% | 7 |
| New York | 24 | 0% | 14 |
| Idaho | 23 | 1% | 9 |
| Minnesota | 21 | 0% | 3 |
| Missouri | 21 | 1% | 0 |
| Kansas | 14 | 1% | 1 |
| South Dakota | 12 | 2% | 5 |
| Utah | 10 | 1% | 1 |
| Louisiana | 9 | 1% | 2 |
| Michigan | 8 | 0% | 1 |
| South Carolina | 8 | 1% | 0 |
| Tennessee | 7 | 1% | 4 |
| Maine | 6 | 0% | 0 |
| Ohio | 6 | 0% | 1 |
| North Carolina | 5 | 0% | 1 |
| Arkansas | 4 | 0% | 0 |
| Iowa | 4 | 0% | 0 |
| Illinois | 4 | 0% | 0 |
| Massachusetts | 4 | 0% | 1 |
| New Hampshire | 4 | 0% | 0 |
| Vermont | 4 | 0% | 4 |
| Connecticut | 3 | 0% | 1 |
| Georgia | 3 | 0% | 0 |
| Kentucky | 2 | 0% | 0 |
| North Dakota | 2 | 1% | 0 |
| District of Columbia | 1 | 7% | 0 |
| Maryland | 1 | 0% | 0 |
Largest water systems with a Surface Water Treatment Rule (SWTR) violation
The ten biggest systems, by people served, whose records include a related violation in the past three years.
| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Phoenix City of Phoenix · Maricopa County |
1,695,000 | 2 | 0 | |
|
Jersey City Mua Jersey City · Hudson County |
262,000 | 1 | 0 | |
|
Gilbert, Town of Gilbert · Maricopa County |
247,600 | 9 | 1 | |
|
Glendale City of Glendale · Maricopa County |
234,766 | 3 | 0 | |
|
Erie City Water Authority Erie County |
220,001 | 3 | 0 | |
|
NJ American Water Short Hills Bedminster Twp, Belvidere Town, Berkeley Heights Twp and 26 more · Essex County |
217,230 | 1 | 0 | |
|
Trenton Water Works Ewing Twp, Hamilton Twp, Hopewell Twp.1106- and 2 more · Mercer County |
217,000 | 8 | 2 | |
|
Wvawc-Kanawha Valley Dist Charleston · Kanawha County |
209,283 | 3 | 0 | |
|
Westminster City of Adams County |
202,078 | 1 | 0 | |
|
City of Shreveport Water System Caddo County |
192,378 | 3 | 0 |
About this data
A system is counted once if any of its violations in the past three years involved Surface Water Treatment Rule (SWTR), including monitoring and reporting lapses. Rules violated and status in the systems table are for the whole system, not Surface Water Treatment Rule (SWTR) alone. Counts cover active systems in all 50 states and the District of Columbia.
Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet.