Nitrate In Drinking Water In Arizona
What residents of Arizona need to know about nitrate in drinking water — including how it enters water, which utilities have documented violations, and what steps to take.
Source: EPA SDWIS, Arizona Department of Environmental Quality (ADEQ), CDC · Last reviewed: 2025-01-01
Quick Answer
Is nitrate in drinking water a real concern in Arizona?
Yes — Yuma County's intensive winter vegetable production and the Salt River Valley's agricultural regions generate nitrate that can affect groundwater used by private wells and some small public systems.
Is this mostly a public-water issue, a private-well issue, or both?
Primarily private well users in agricultural portions of the state; public water systems are monitored by ADEQ.
What is the main reason residents should care?
Yuma County is one of the U.S.'s most productive winter vegetable growing regions, with intensive fertilizer use. The Salt River Valley (Greater Phoenix agricultural fringe) also has documented agricultural nitrate in some groundwater areas.
Key Facts
| EPA Nitrate MCL | 10 mg/L as N |
| Yuma County context | Major winter vegetable growing region with intensive fertilizer use |
| Groundwater concern | ADEQ has documented nitrate in agricultural groundwater areas |
| Private well risk | Owner's responsibility to test — no automatic monitoring for private wells |
| State oversight | Arizona Department of Environmental Quality (ADEQ) |
Why This Matters in Arizona
Arizona's Yuma County produces a large percentage of the nation's winter lettuce, broccoli, and other vegetables, using intensive irrigation and fertilizer application on desert soils. This agricultural activity has been documented to affect groundwater nitrate in some areas. The state's groundwater scarcity means communities that do rely on local aquifers may draw from water sources susceptible to agricultural contamination. ADEQ monitors public water systems for nitrate compliance and has documented nitrate in groundwater in some agricultural portions of the state.
Critical — Infants Under 6 Months
Do not use tap water that exceeds 10 mg/L nitrate-nitrogen to prepare infant formula or feed infants under six months. Boiling will concentrate nitrate — do not boil. Use bottled water or a certified reverse osmosis system (NSF/ANSI 58) until the issue is resolved.
Arizona Utilities With Nitrate Violation Records
The utilities listed below have at least one nitrate violation on record in EPA's SDWIS database. Violations may be open or resolved — see individual utility pages for current status and risk level.
City of Tucson
Tucson · 732,906 served
City of Mesa
Mesa · 466,000 served
Town of Gilbert
Gilbert · 247,600 served
City of Chandler
Chandler · 247,328 served
City of Scottsdale
Scottsdale · 241,361 served
City of Glendale
Glendale · 234,766 served
City of Peoria
Peoria · 187,676 served
City of Tempe
Tempe · 165,000 served
Arizona Water Co - Pinal Valley
Casa Grande · 134,432 served
Epcor - Agua Fria
Surprise · 127,718 served
How Nitrate Gets Into Drinking Water
Agricultural fertilizer and manure runoff
Nitrogen-based fertilizers and animal waste applied to Arizona cropland can leach into groundwater or run off into surface water supplies. This is the dominant nitrate pathway in most agricultural regions.
Septic system effluent
Failing or poorly sited septic systems release nitrogen-rich wastewater near drinking water wells. Rural areas with high well density and aging septic infrastructure face elevated risk.
Concentrated animal feeding operations (CAFOs)
Large livestock facilities generate significant waste. Lagoon leaks and overapplication of manure to nearby fields can create localized nitrate hotspots in groundwater.
Natural geological deposits
In some regions, naturally occurring nitrogen compounds in soil and bedrock contribute background nitrate levels to groundwater independent of agricultural activity.
Who Should Pay Closest Attention
Private well users in Yuma County and other agricultural portions of Arizona should test for nitrate. Given the arid climate, many rural Arizona residents rely on bottled water for drinking; those using well water should test before providing it to infants.
Households with infants under six months
Pregnant residents
Private well owners in agricultural areas
Households near livestock operations or CAFOs
Rural residents on shallow groundwater wells
Households with older or failing septic systems nearby
How to Check Your Situation in Arizona
- 1
Identify your water utility. Use the ZIP lookup below or browse the Arizona utility directory on this site.
- 2
Read your utility's page on this site to see its current risk level and any open nitrate violations.
- 3
Review your utility's most recent Consumer Confidence Report (CCR) — mailed annually or available on the utility's website. It must disclose any MCL exceedances.
- 4
If you are on a private well, arrange testing at a Arizona Department of Environmental Quality (ADEQ)-certified lab. Your state health department maintains a list of certified labs. Annual testing is recommended in agricultural areas.
- 5
If you have an infant under six months, use bottled water or a certified RO system (NSF/ANSI 58) immediately as a precautionary measure — do not wait for test results if you are in a high-risk area.
- 6
If your utility issues a nitrate exceedance notice, follow their guidance and do not use tap water for infants until the issue is resolved.
Treatment Options
Carbon filters and boiling do not remove nitrate. Only the options below are effective.
NSF/ANSI Standard 58 — Reverse Osmosis
RO systems certified to NSF/ANSI 58 reduce nitrate by 85–95% at the point of use. Under-sink installation required. The most practical residential option for nitrate concerns.
Distillation
Distillation units effectively remove nitrate along with most other dissolved contaminants. Suitable for drinking and cooking water — not whole-house use.
Anion Exchange
Ion exchange systems designed for nitrate removal exchange nitrate ions for chloride on a resin bed. Effective as a point-of-entry system; requires periodic regeneration and monitoring.
Carbon filters do NOT remove nitrate
Standard pitcher filters, faucet filters, and under-sink carbon units — including those certified NSF/ANSI 42 or 53 — do not remove nitrate. Do not use these for nitrate reduction.
Frequently Asked Questions
Related Pages
Nitrate — National Overview
All U.S. utilities with nitrate records
Arizona State Overview
All utilities and water quality data
Lead in Drinking Water
A separate but common concern
Reverse Osmosis Guide
Removes 85–95% of nitrate
Well Water Guide
Private well testing and safety
All Contaminants
Complete reference library
Data Sources & Provenance
All data on this page is sourced from official U.S. government or public datasets.
Find Your Utility
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Arizona Department of Environmental Quality (ADEQ) ↗