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 still unresolved. What TTHM (Total Trihalomethanes) is and why it matters.
Systems with a TTHM (Total Trihalomethanes) violation
Unresolved first, then largest first| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Lake Havasu City of Lake Havasu City · Mohave County |
54,610 | 2 | 0 | |
|
Goodyear Water Department Goodyear · Maricopa County |
50,001 | 4 | 0 | |
|
San Luis City of San Luis · Yuma County |
39,705 | 4 | 1 | |
|
Florence Water Company Florence · Pinal County |
14,593 | 5 | 1 | |
|
Tolleson City of Tolleson · Maricopa County |
9,300 | 4 | 0 | |
|
Usaf Luke Air Force Base Litchfield Park · Maricopa County |
8,440 | 2 | 0 | |
|
Usmc Yuma Main System Yuma · Yuma County |
8,353 | 6 | 0 | |
|
Morenci Water Elec CO Main Morenci · Greenlee County |
4,078 | 5 | 0 | |
|
Adoc Eyman Unit Florence · Pinal County |
3,969 | 8 | 2 | |
|
Carefree Water Company Carefree · Maricopa County |
3,588 | 3 | 0 | |
|
Wellton Town of Wellton · Yuma County |
3,000 | 10 | 1 | |
|
Camp Verde School Dist 28 Camp Verde · Yavapai County |
1,810 | 4 | 3 | |
|
Cameron Trading Post Cameron · Coconino County |
1,270 | 8 | 1 | |
|
Adoc Florence Asp Florence · Pinal County |
1,001 | 8 | 4 | |
|
Epcor Marina Village Parker · La Paz County |
528 | 1 | 0 | |
|
CS White Hills Water Company Unit 1 White Hills · Mohave County |
338 | 4 | 0 | |
|
CS White Hills Water Company Units 3 4 6 White Hills · Mohave County |
333 | 4 | 0 | |
|
Cibola Water Improvement District Cibola · La Paz County |
197 | 8 | 2 | |
|
Mohawk Valley School District Roll · Yuma County |
171 | 7 | 0 | |
|
Beaver Creek Store Beaver Creek · Yavapai County |
100 | 5 | 3 | |
|
Rio Verde RV Park Cottonwood · Yavapai County |
90 | 2 | 1 | |
|
Bonita Creek Water Company Payson · Gila County |
67 | 9 | 1 | |
|
Retaw Water Company Lakeside · Navajo County |
54 | 4 | 2 | |
|
Gilbert, Town of Gilbert · Maricopa County |
247,600 | 9 | 1 | |
|
GW Santa Cruz Water CO Maricopa · Pinal County |
84,000 | 7 | 0 | |
|
Town of Prescott Valley Prescott Valley · Yavapai County |
57,048 | 1 | 0 | |
|
Bullhead City Mohave Bullhead City · Mohave County |
36,330 | 13 | 1 | |
|
Foothills Water and Sewer LLC Yuma · Yuma County |
32,425 | 5 | 0 | |
|
Nogales City of Nogales · Santa Cruz County |
22,000 | 7 | 0 | |
|
Safford City of Safford · Graham County |
20,600 | 5 | 1 | |
|
Arizona Water CO White Tanks White Tanks · Maricopa County |
18,858 | 2 | 0 | |
|
Liberty Water Rio Rico Rio Rico · Santa Cruz County |
17,960 | 3 | 0 | |
|
Grand Canyon National Park Grand Canyon · Coconino County |
16,590 | 7 | 0 | |
|
Flowing Wells Irrigation District Tucson · Pima County |
16,000 | 6 | 1 | |
|
Apache Junction Water District Apache Junction · Pinal County |
15,610 | 6 | 0 | |
|
Fort Defiance-Window Rock-St Michaels Ntua Fort Defiance, Window Rock, St. Michaels · County |
12,869 | 3 | 1 | |
|
Eloy City of Eloy · Pinal County |
8,999 | 6 | 1 | |
|
Green Valley Dwid Green Valley · Pima County |
8,687 | 3 | 1 | |
|
Scua Upper Seven Mile County |
8,478 | 12 | 3 | |
|
Globe City of Globe · Gila County |
7,536 | 4 | 0 | |
|
Valley Pioneers Water Company INC Kingman · Mohave County |
6,263 | 4 | 0 | |
|
Snowflake Town of Snowflake · Navajo County |
5,590 | 4 | 0 | |
|
Metropolitan Dwid Diablo Village Tucson · Pima County |
5,542 | 3 | 0 | |
|
Ponderosa Dwid Pinetop · Navajo County |
5,375 | 3 | 0 | |
|
North Mohave Valley Bullhead City · Mohave County |
5,190 | 6 | 2 | |
|
Dilkon-Indian Wells-Greasewood-White Cone Ntua Dilcon, Indian Wells, Lower Greasewood · County |
4,986 | 2 | 1 | |
|
Eagar Town of Eagar · Apache County |
4,590 | 5 | 1 | |
|
Cottonwood Municipal Water VV6 Cottonwood · Yavapai County |
4,518 | 2 | 0 | |
|
Metropolitan Dwid Hub Tucson · Pima County |
4,252 | 1 | 0 | |
|
Aspc Yuma Yuma · Yuma County |
4,197 | 4 | 0 |
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. Retrieved from ECHO on Oct 11, 2026.