Stage 1 Disinfectants and DBP Rule in drinking water
126 active public water systems in 23 states had a Stage 1 Disinfectants and DBP Rule violation in the past three years, and 126 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 Stage 1 Disinfectants and DBP Rule and lists the water systems whose records include a related violation. It does not show measured levels.
Is Stage 1 Disinfectants and DBP Rule 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 1998 Stage 1 Rule was the first comprehensive federal standard for disinfection byproducts. It set MCLs for TTHM and HAA5, added limits for bromate (formed during ozonation) and chlorite (formed during chlorine dioxide treatment), and established maximum residual disinfectant levels (MRDLs) for chlorine, chloramines, and chlorine dioxide. It applies to all community and non-transient non-community water systems that disinfect.
Health effects
See TTHMs (2950) and HAA5 (2456) for their specific health effects. Bromate is a probable human carcinogen (Group B2). Chlorite at elevated levels can cause hemolytic anemia, particularly in infants, developing fetuses, and individuals with certain enzyme deficiencies. Violations indicate the system exceeded one or more of these byproduct or disinfectant limits.
The standard and what a violation means
EPA limit: TTHM: 0.080 mg/L; HAA5: 0.060 mg/L; Bromate: 0.010 mg/L; Chlorite: 1.0 mg/L.
Water systems with a Stage 1 Disinfectants and DBP Rule 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 |
|---|---|---|---|
| West Virginia | 21 | 3% | 21 |
| Arkansas | 18 | 2% | 18 |
| Colorado | 16 | 1% | 16 |
| New York | 16 | 0% | 16 |
| South Dakota | 9 | 1% | 9 |
| Minnesota | 6 | 0% | 6 |
| California | 5 | 0% | 5 |
| Missouri | 4 | 0% | 4 |
| Ohio | 4 | 0% | 4 |
| Wisconsin | 4 | 0% | 4 |
| Tennessee | 3 | 0% | 3 |
| Virginia | 3 | 0% | 3 |
| Arizona | 2 | 0% | 2 |
| Iowa | 2 | 0% | 2 |
| Massachusetts | 2 | 0% | 2 |
| New Jersey | 2 | 0% | 2 |
| Nevada | 2 | 0% | 2 |
| Oregon | 2 | 0% | 2 |
| Delaware | 1 | 0% | 1 |
| Georgia | 1 | 0% | 1 |
| Idaho | 1 | 0% | 1 |
| Kentucky | 1 | 0% | 1 |
| Michigan | 1 | 0% | 1 |
Largest water systems with a Stage 1 Disinfectants and DBP Rule 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 |
|---|---|---|---|---|
|
Cohoes City Cohoes (c) · Albany County |
18,447 | 4 | 1 | |
|
Medford Twp Dept of Muni Medford Twp · Burlington County |
17,272 | 1 | 1 | |
|
Steubenville, City of Jefferson County |
17,000 | 2 | 1 | |
|
Marion Waterworks Crittenden County |
14,185 | 2 | 1 | |
|
Ak-Chin Village Ak-chin Village · County |
11,646 | 6 | 1 | |
|
Covington, City of Covington City · County |
5,961 | 6 | 1 | |
|
Manchester Manchester · Meriwether County |
5,397 | 4 | 2 | |
|
Advenir French Quarter Denver · Denver County |
3,447 | 2 | 1 | |
|
Odrc-Pickaway Correction PWS Pickaway County |
3,376 | 6 | 4 | |
|
Gladwin, City of Gladwin · Gladwin County |
2,933 | 3 | 1 |
About this data
A system is counted once if any of its violations in the past three years involved Stage 1 Disinfectants and DBP Rule, including monitoring and reporting lapses. Rules violated and status in the systems table are for the whole system, not Stage 1 Disinfectants and DBP Rule 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.