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Arizona Tap Water Quality Rankings 2026: 41st in Nation | WaterQ

Alex Carter
By Alex Carter
Water Quality Researcher · Published 2026-04-09

Arizona ranks 41st in our 2026 national tap water quality analysis. The state's desert geology means naturally occurring arsenic is far more common in groundwater here than in most of the country, and that single factor — more than any industrial contamination — drives much of Arizona's overall standing.

Key Findings for Arizona

Reviewing EPA SDWIS data for 2026, three themes define Arizona's water quality landscape:

  • Naturally Occurring Arsenic: Much of central and southern Arizona's groundwater contains naturally elevated arsenic due to the region's volcanic and sedimentary geology. Since the EPA tightened the arsenic standard to 10 parts per billion in 2006, many Arizona systems have had to install dedicated arsenic removal treatment.
  • Colorado River Dependence: Phoenix, Tucson, and much of central Arizona rely on a blend of Colorado River water (via the Central Arizona Project canal) and groundwater. Ongoing drought conditions on the Colorado River have made water supply planning, not just water quality, a major focus for the state.
  • PFAS Near Military Airfields: Sites near current and former military installations, including areas around Tucson, have been associated with PFAS detections in groundwater linked to historical firefighting foam use.

Most Common Contaminants in Arizona

Here's what Arizona residents should know about the contaminants most relevant to their water:

1. Arsenic

Arsenic is naturally present in many Arizona aquifers. Public water systems are required to treat to below the federal standard, typically using adsorption or ion-exchange media, but private well owners in affected areas are not covered by these systems and should test independently.

2. PFAS ("Forever Chemicals")

PFAS contamination near military airfields, particularly around Tucson, has prompted targeted groundwater monitoring and, in some cases, treatment or alternative source development for affected water providers.

3. Total Dissolved Solids and Hardness

Groundwater-dependent communities across Arizona often have higher mineral content, contributing to water hardness. While generally not a health concern at typical levels, it affects taste, appliance scaling, and soap efficiency, and is a common reason residents install water softeners.

Arizona's Best and Worst Cities for Water Quality

Explore the full breakdown on our Arizona water systems page.

Top Performers: Phoenix and Tucson's large utilities, which blend Colorado River water with groundwater and operate extensive treatment infrastructure, generally maintain strong compliance records.

Areas to Watch: Smaller groundwater-dependent systems in central and southern Arizona are the ones most likely to require ongoing arsenic treatment, and areas near military airfields remain a focus for PFAS monitoring.

What Arizona Residents Should Do

Given Arizona's 41st place ranking, here's what matters most for residents:

  1. Search Your System's Record: Use the WaterQ search tool to check your water system's arsenic and PFAS compliance history.
  2. Test Private Wells for Arsenic: If you're on a private well in central or southern Arizona, arsenic testing is one of the most important things you can do, since natural background levels vary significantly even within the same area.
  3. Consider Reverse Osmosis: RO systems are effective at reducing both arsenic and PFAS at the point of use, and are a common choice for Arizona households on private wells.
  4. Check PFAS Updates If Near a Military Site: Residents near current or former military airfields should check their utility's PFAS monitoring results.

Frequently Asked Questions

How does Arizona water quality compare to other states?

Arizona ranks 41st in the nation for 2026. Arizona's score is shaped largely by naturally occurring arsenic in groundwater across much of the state, which requires many systems to operate dedicated arsenic treatment, plus localized PFAS contamination near current and former military airfields.

What are the most common contaminants in Arizona tap water?

The leading concerns in Arizona are Arsenic (naturally occurring in groundwater across much of the state, especially in central and southern Arizona), PFAS (linked to firefighting foam use at military airfields including sites near Tucson), and Total Dissolved Solids / hardness in groundwater-dependent communities.

Is it safe to drink tap water in Arizona?

Yes, for systems in compliance with the EPA's arsenic standard, which Arizona utilities have invested heavily in meeting since the standard was tightened in 2006. Phoenix and Tucson, which blend Colorado River and Central Arizona Project water with groundwater, generally meet all federal standards. Residents on private wells in areas with naturally high arsenic should test independently, since private wells are not covered by these municipal treatment systems.

Source: Arizona Department of Environmental Quality Safe Drinking Water Program, EPA SDWIS 2026 Compliance Data, and WaterQ National Database. For more information on our ranking process, visit our state rankings page.