ADEQ works closely with two of Arizona's most populous counties to administer the provisions of the Safe Drinking Water Act and our state's drinking water rules .

Maricopa County's Drinking Water Program oversees inspections, engineering plan reviews, and compliance and enforcement activities for all public water systems in the county. ADEQ still maintains oversight of county and state facilities within the county. The county's drinking water program can be reached at (602) 506-6935.

The Pima County Health Department has limited oversight of some engineering plan reviews within their county. ADEQ's Southern Regional Office, located in Tucson, inspects public water systems and ensures compliance within Pima County. The Pima County Health Department can be reached at (520) 740-8261.

ADEQ oversees all aspects of the state's safe drinking water programs throughout the rest of the state, except federal facilities and tribal lands. Facilities in these categories are regulated by the Environmental Protection Agency directly.