TTHM (Total Trihalomethanes) violations in Arizona
218 active public water systems in Arizona had a TTHM (Total Trihalomethanes) violation in the past three years, 23 of them in the latest quarter of EPA's data. What TTHM (Total Trihalomethanes) is and why it matters.
Systems with a TTHM (Total Trihalomethanes) violation
Latest quarter first, then largest first| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Town of Taylor Taylor · Navajo County |
4,190 | 7 | 2 | |
|
ST Johns City of Saint Johns · Apache County |
3,500 | 5 | 1 | |
|
City of Willcox Willcox · Cochise County |
3,236 | 6 | 0 | |
|
Scua Bylas Bylas · County |
3,160 | 12 | 3 | |
|
Desert Foothills Bullhead City · Mohave County |
3,091 | 6 | 1 | |
|
Tucson Medical Center Tucson · Pima County |
3,000 | 4 | 1 | |
|
Hondah Casino County |
2,926 | 6 | 1 | |
|
Wickenburg Ranch Estates Wickenburg · Yavapai County |
2,877 | 1 | 0 | |
|
Goodman Water Company Catalina · Pinal County |
2,668 | 2 | 0 | |
|
Ajo Improvement Company Ajo · Pima County |
2,654 | 2 | 0 | |
|
CS los Cerros Water Company INC Catalina · Pima County |
2,613 | 1 | 0 | |
|
Wmatua Cibecue Cibecue · County |
2,590 | 3 | 2 | |
|
Tonto Apache County |
2,580 | 6 | 1 | |
|
Picacho Water Company Casa Grande · Pinal County |
2,440 | 3 | 1 | |
|
Valle Verde Water Company East Nogales · Santa Cruz County |
2,397 | 4 | 0 | |
|
Chino Meadows II Chino Valley · Yavapai County |
2,350 | 6 | 4 | |
|
MT Tipton Water Company Dolan Springs · Mohave County |
2,257 | 5 | 0 | |
|
Cottonwood Municipal Water Vsf1 Cornville · Yavapai County |
2,196 | 1 | 0 | |
|
Kearny Town of Kearny · Pinal County |
1,950 | 2 | 0 | |
|
Marana Dwid Derringer Marana · Pima County |
1,950 | 4 | 0 | |
|
Joseph City Dwid Joseph City · Navajo County |
1,811 | 4 | 1 | |
|
Sheraton Phoenix Downtown Morristown · Maricopa County |
1,804 | 4 | 1 | |
|
Town of Huachuca City Huachuca City · Cochise County |
1,750 | 5 | 0 | |
|
Petrified Forest NP Holbrook · Apache County |
1,742 | 5 | 0 | |
|
Upper Moenkopi Upper Moenkopi · County |
1,740 | 2 | 0 | |
|
Vail School District Elementary School Vail · Pima County |
1,680 | 3 | 0 | |
|
Hotevilla Village Hotevilla, Hotevilla/bacavi Community Sc · County |
1,601 | 8 | 4 | |
|
San Xavier West San Xavier West · County |
1,511 | 2 | 0 | |
|
Sunrise Vista Utilities Sunrise Vistas · Mohave County |
1,500 | 3 | 1 | |
|
Bearizona Williams · Coconino County |
1,423 | 6 | 0 | |
|
Mayer Dwid Mayer · Yavapai County |
1,400 | 7 | 1 | |
|
Mescal Lakes Water System Benson · Cochise County |
1,398 | 2 | 1 | |
|
Katherine Landing Dwtp Katherine Landing · Mohave County |
1,300 | 5 | 0 | |
|
White Mountain Summer Homes Dwid Pinetop · Navajo County |
1,233 | 7 | 1 | |
|
West End Water Company Wittman Wittmann · Maricopa County |
1,200 | 1 | 0 | |
|
Mammoth Town of Mammoth · Pinal County |
1,181 | 6 | 1 | |
|
Baca Float Water Company Tubac · Santa Cruz County |
1,162 | 1 | 0 | |
|
Vaya Chin Intertie Vaya Chin, Hickiwan, San Simon Village/s · County |
1,151 | 2 | 0 | |
|
Lechee Ntua Le Chee · County |
1,115 | 2 | 1 | |
|
Cocopah Bend RV & Golf Resort County |
1,095 | 2 | 0 | |
|
Copper Mountain Ranch Cfd Maricopa · Pinal County |
1,071 | 4 | 0 | |
|
Hopi High School Bia Hopi High School · County |
1,005 | 11 | 4 | |
|
Payson Water Mesa de Caballo Payson · Gila County |
976 | 2 | 0 | |
|
Bacavi Village Bacavi · County |
943 | 3 | 1 | |
|
Timberland Acres Dwid Show Low · Navajo County |
922 | 3 | 0 | |
|
Freeport McMoran Miami Barney Inspiration · Gila County |
916 | 1 | 0 | |
|
Metropolitan Dwid E&t System Tucson · Pima County |
880 | 2 | 0 | |
|
Heber Dwid Heber · Navajo County |
839 | 5 | 2 | |
|
Pinal County Justice Complex Florence · Pinal County |
820 | 6 | 2 | |
|
Adoc Aspc Fort Grant Bonita · Graham County |
800 | 7 | 1 |
About this data
A system is counted once if any of its violations in the past three years involved TTHM (Total Trihalomethanes), including monitoring and reporting lapses. Rules violated and status in the table are for the whole system, not TTHM (Total Trihalomethanes) alone.
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 Arizona 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.