Long Term 2 Enhanced Surface Water Treatment Rule (LT2) in drinking water
221 active public water systems in 32 states had a Long Term 2 Enhanced Surface Water Treatment Rule (LT2) violation in the past three years, and 146 have one that is still unresolved.
You are on Tapcensus, an independent guide to the EPA compliance records of every public water system in the United States. This page explains Long Term 2 Enhanced Surface Water Treatment Rule (LT2) and lists the water systems whose records include a related violation. It does not show measured levels.
Is Long Term 2 Enhanced Surface Water Treatment Rule (LT2) 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.
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What it is and where it comes from
The LT2 ESWTR (2006) required all surface water and GWUDI systems to monitor source water for Cryptosporidium, then apply additional treatment based on measured concentrations. Higher-bin systems (more oocysts detected) must install advanced treatment — UV disinfection, ozone, or membrane filtration — beyond the original SWTR requirements.
Health effects
Cryptosporidium is a chlorine-resistant protozoan parasite that causes cryptosporidiosis — severe watery diarrhea, cramping, nausea, and fever. In immunocompromised individuals (HIV/AIDS, transplant recipients), it can be life-threatening and prolonged. Infants and the elderly are also at elevated risk. LT2 violations indicate failure to complete monitoring or apply the required additional treatment tier.
The standard and what a violation means
EPA limit: Treatment technique — additional Cryptosporidium treatment based on bin classification.
Water systems with a Long Term 2 Enhanced Surface Water Treatment Rule (LT2) 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 | Unresolved |
|---|---|---|---|
| West Virginia | 68 | 9% | 68 |
| Texas | 20 | 0% | 8 |
| Tennessee | 15 | 2% | 13 |
| Illinois | 14 | 0% | 0 |
| California | 10 | 0% | 9 |
| New York | 8 | 0% | 4 |
| Ohio | 8 | 0% | 5 |
| Louisiana | 7 | 1% | 5 |
| Montana | 7 | 0% | 1 |
| New Mexico | 7 | 1% | 7 |
| Pennsylvania | 7 | 0% | 0 |
| Oregon | 6 | 0% | 4 |
| Wyoming | 5 | 1% | 2 |
| Alaska | 4 | 0% | 4 |
| Kentucky | 4 | 1% | 3 |
| Utah | 4 | 0% | 0 |
| Washington | 4 | 0% | 0 |
| Colorado | 3 | 0% | 3 |
| Missouri | 3 | 0% | 3 |
| Arizona | 2 | 0% | 0 |
| Kansas | 2 | 0% | 1 |
| Massachusetts | 2 | 0% | 1 |
| Oklahoma | 2 | 0% | 0 |
| Alabama | 1 | 0% | 1 |
| District of Columbia | 1 | 7% | 1 |
| Iowa | 1 | 0% | 0 |
| Indiana | 1 | 0% | 1 |
| Maryland | 1 | 0% | 0 |
| Minnesota | 1 | 0% | 1 |
| North Carolina | 1 | 0% | 0 |
| New Hampshire | 1 | 0% | 0 |
| South Dakota | 1 | 0% | 1 |
Largest water systems with a Long Term 2 Enhanced Surface Water Treatment Rule (LT2) 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 |
|---|---|---|---|---|
|
New York City System New York (c) · Bronx County |
8,271,000 | 1 | 1 | |
|
Portland Water Bureau Multnomah County |
666,200 | 1 | 1 | |
|
Syracuse City Syracuse (c) · Onondaga County |
192,000 | 3 | 2 | |
|
City of Georgetown Williamson County |
191,639 | 3 | 0 | |
|
Peoria City of Peoria · Maricopa County |
187,676 | 4 | 1 | |
|
Asheville City of Asheville · Buncombe County |
157,431 | 2 | 0 | |
|
Reading Area Water Authority Berks County |
95,100 | 1 | 0 | |
|
City of Pflugerville Travis County |
63,464 | 3 | 0 | |
|
City of Monroe Water System Ouachita County |
57,000 | 3 | 0 | |
|
Yucaipa Valley Water District San Bernardino County |
52,202 | 3 | 0 |
About this data
A system is counted once if any of its violations in the past three years involved Long Term 2 Enhanced Surface Water Treatment Rule (LT2), including monitoring and reporting lapses. Rules violated and status in the systems table are for the whole system, not Long Term 2 Enhanced Surface Water Treatment Rule (LT2) 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.