Updated April 2026 · EPA SDWIS data
Arizona Drinking Water Quality
5 water systems · 3,388,834 people served · Avg score: 62
Arizona has 5 public water systems serving 3,388,834 people, with an average Water Safety Score of 62 of 100 (mixed). EPA SDWIS records show 4 systems with at least one open or recent violation.
How Arizona Compares Nationally
Arizona runs 19.0 points below the U.S. average Water Safety Score of 81.0 — meaningfully worse than the typical state, usually a sign of older infrastructure, more small-system capacity gaps, or source-water challenges.
4 of 5 Arizona water systems (80%) have an open or recent EPA violation — well above the U.S. average. The concentration is typical of states with many small rural systems where compliance staffing is thin.
The most-detected contaminants flagged in EPA SDWIS for Arizona are Arsenic (4 systems) and Gross Alpha (4 systems). These typically reflect either source-water characteristics — agricultural runoff for nitrate, geology for arsenic, industrial proximity for PFAS — or distribution-system effects like lead from service lines and disinfection byproducts.
Why Arizona Looks the Way It Does
Three factors usually explain a state's drinking water profile. First, source water — states drawing primarily from deep protected aquifers face fewer treatment challenges than states reliant on surface water downstream of agriculture or industry. Second, infrastructure age — older Northeast and Midwest distribution networks carry more lead service lines and aging treatment plants, which surface as monitoring or contaminant violations. Third, system-size mix — states with many small rural systems concentrate violations because small systems have thinner compliance staffs.
Arizona's federal regulatory enforcement runs under the EPA primacy framework, which delegates Safe Drinking Water Act enforcement to the state drinking water program with EPA oversight. State enforcement capacity varies, which is one of the reasons two neighboring states with similar source water can have very different violation rates in EPA SDWIS records.
How These Numbers Are Calculated
All counts and scores on this page come directly from the EPA Safe Drinking Water Information System (SDWIS). Contaminant Maximum Contaminant Levels (MCLs) come from EPA's National Primary Drinking Water Regulations. The Water Safety Score weights health violations 40%, contaminant exceedances 30%, enforcement actions 20%, and monitoring violations 10%. Read the full IsWaterSafe methodology for the join logic and refresh cadence.
Frequently Asked Questions
How many public water systems does Arizona have?
Arizona has 5 public water systems registered in the EPA Safe Drinking Water Information System (SDWIS), serving an estimated 3,388,834 residents. The systems range from large municipal utilities serving entire metro areas to small community systems serving a few hundred customers.
Is Arizona drinking water safe?
Arizona's average Water Safety Score is 62 of 100. Arizona runs 19.0 points below the U.S. average Water Safety Score of 81.0 — meaningfully worse than the typical state, usually a sign of older infrastructure, more small-system capacity gaps, or source-water challenges. 4 of 5 Arizona water systems (80%) have an open or recent EPA violation — well above the U.S. average. The concentration is typical of states with many small rural systems where compliance staffing is thin. An EPA Maximum Contaminant Level violation is a regulatory event, not a clinical diagnosis — see the IsWaterSafe disclaimer for the distinction.
Which contaminants matter most in Arizona?
The most-detected contaminants flagged in EPA SDWIS for Arizona are Arsenic (4 systems) and Gross Alpha (4 systems). These typically reflect either source-water characteristics — agricultural runoff for nitrate, geology for arsenic, industrial proximity for PFAS — or distribution-system effects like lead from service lines and disinfection byproducts.
Where can I find my Arizona utility's official report?
Every community water system in Arizona is required by the Safe Drinking Water Act to publish an annual Consumer Confidence Report (CCR) by July 1, listing every regulated contaminant detected and how it compared to the EPA Maximum Contaminant Level. CCRs are typically posted on each utility's website. The state's drinking water program (operating under EPA primacy) maintains a portal of CCR links and enforcement records.
How is Arizona's data updated?
EPA refreshes SDWIS quarterly, and IsWaterSafe re-runs the Arizona state and ranking pages against each new release. Last refreshed April 2026. Note that violations have a typical 60–90 day reporting lag from the date of detection.
Sources: EPA Safe Drinking Water Information System (SDWIS), EPA National Primary Drinking Water Regulations, EWG Tap Water Database. SDWIS and EPA regulations are U.S. government public domain. Cite as: "IsWaterSafe, Arizona, April 2026 reading. Data: EPA SDWIS."
Last updated 2026-04-04 · 5 Arizona systems tracked.
For this entity, the underlying data on this page comes from the EPA Safe Drinking Water Information System (SDWIS). The breakdown above is the federal record; the paragraphs below add the per-entity context that makes the headline numbers usable for a real decision rather than just a data lookup.
Every number on this page links back to the EPA Safe Drinking Water Information System (SDWIS); the methodology page describes the inputs, refresh cadence, and known limitations of the underlying data product.
For readers using this page as a decision input, the related-entity pages elsewhere on the site provide the comparison set. The most useful comparison for this entity is typically a peer within U.S. public water systems with similar size, similar exposure, or similar geography — not the national-level summary alone.