Tapcensus

Arizona drinking water quality

Arizona has 1,721 active public water systems serving 7.7 million people. 1,300 of them, 76%, had at least one EPA violation in the past three years, 480 have an unresolved violation today, and 66 are designated serious violators by the EPA.

Active systems 1,721 in 15 counties
People served 7.7M 920 community systems serve 7.4M
Violations, past 3 years 1,300 76% of active systems
Serious violators 66 116 systems carry a health flag

Largest counties

All 15 counties
CountyPeople servedSystemsWith violations
Maricopa4,429,333217139
Pima1,136,697193127
Pinal506,3979580
Mohave232,46412099
Yavapai224,970238162
Yuma219,4525046
Coconino179,88111596
Cochise130,49510586
Navajo98,1566251
Gila61,82710076

Largest community water systems

All 1,721 systems
SystemServesStatus
Phoenix City of
Maricopa County		 1,695,000
Tucson City of
Pima County		 732,906
Mesa City of
Maricopa County		 466,000
Gilbert, Town of
Maricopa County		 247,600
Chandler City of
Maricopa County		 247,328
Scottsdale City of
Maricopa County		 241,361
Glendale City of
Maricopa County		 234,766
Peoria City of
Maricopa County		 187,676
Tempe City of
Maricopa County		 165,000
Arizona Water CO Pinal Valley
Pinal County		 134,432

About the Arizona data

Retrieved from EPA ECHO on Oct 11, 2026.

Most common violations in Arizona

Revised Total Coliform Rule (RTCR)495 systemsChlorine (MRDL)275 systemsPublic Notification Rule222 systemsTTHM (Total Trihalomethanes)219 systemsNitrate215 systems
All contaminants and rules in Arizona

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