State Well Water Guide
Arizona Private Well Water Guide
Arizona's private well users — primarily in rural areas outside the Phoenix and Tucson metro served areas — face some of the most challenging well water conditions in the nation. The state's arid geology concentrates naturally occurring contaminants including arsenic, uranium, fluoride, and chromium-6 in groundwater. Aquifer overdraft is also a serious concern, with many rural Arizona wells experiencing declining water levels. The Arizona Department of Environmental Quality (ADEQ) regulates public water systems; private domestic wells (fewer than 5 service connections) are minimally regulated.
Testing Guidance
ADEQ and University of Arizona Extension recommend annual testing for bacteria and nitrates as a minimum. Given Arizona's geology, arsenic testing is strongly recommended for all wells — Arizona has documented some of the highest naturally occurring arsenic in groundwater in the United States. Testing for uranium, fluoride, and chromium-6 is advised based on location. All new wells and wells that haven't been tested in 3+ years should receive a comprehensive panel including heavy metals, radiologicals, and VOCs.
What to Test For in Arizona
Total coliform bacteria and E. coli — annual minimum for all wells
Arsenic — all Arizona wells; state ranks among highest naturally occurring arsenic in the nation
Uranium — granitic geology areas; southeastern Arizona, Prescott region
Fluoride — many rural Arizona aquifers have naturally elevated fluoride; some areas exceed the EPA MCL of 4 mg/L
Chromium-6 — Prescott Valley area, Gila River basin, and near industrial sites
Nitrates — wells near agricultural areas, feedlots, or septic systems
Perchlorate — Phoenix metro area, Litchfield Park, and areas with aerospace/defense industry history
Total dissolved solids and hardness — Arizona groundwater is typically very hard (200–600+ mg/L)
PFAS — near Luke Air Force Base, Davis-Monthan, Fort Huachuca, and other military installations
Iron and manganese — some rural areas of central and eastern Arizona
Common Contamination Risks in Arizona
Arsenic — Arizona consistently reports among the highest naturally occurring arsenic concentrations in U.S. groundwater; volcanic and sedimentary geology releases arsenic across much of the state
Uranium from granitic and sedimentary rock — southeastern Arizona and the Prescott region have documented uranium in groundwater from naturally occurring ore deposits
Fluoride from volcanic geology — naturally elevated fluoride occurs in many areas; the Tucson Basin, parts of Yavapai County, and eastern Arizona have documented levels at or above the EPA MCL
Perchlorate in the Phoenix area — legacy aerospace and defense industry contamination has left perchlorate plumes affecting groundwater in parts of the West Valley
Aquifer depletion — many rural Arizona aquifers are being pumped faster than natural recharge, causing water quality changes (increased mineral concentration, arsenic mobilization) as water tables drop
PFAS from military and aviation — Luke AFB, Davis-Monthan, Fort Huachuca, and commercial airports have documented PFAS releases affecting surrounding groundwater
Extreme water hardness — Arizona groundwater is among the hardest in the nation; scale buildup in pipes and appliances is nearly universal without treatment
Contaminant Guides Relevant to AZ Wells
PFAS
Synthetic Chemicals
EPA limit: 4 ppt
Lead
Heavy Metals
EPA limit: 15 ppb (action level)
Nitrates
Agricultural Chemicals
EPA limit: 10 mg/L
DBPs
Disinfection Byproducts
EPA limit: 80 µg/L (TTHMs) / 60 µg/L (HAA5)
Arsenic
Heavy Metals
EPA limit: 10 ppb
Hard Water
Minerals
EPA limit: No federal limit
Chlorine
Disinfection Chemicals
EPA limit: 4 mg/L (MRDL)
Microplastics
Emerging Contaminants
EPA limit: No federal limit
Bacteria
Microbial Contamination
EPA limit: Zero E. coli / < 1 coliform per 100 mL
Fluoride
Minerals
EPA limit: 4 mg/L (MCL) / 2 mg/L (Secondary MCL)
Chromium-6
Heavy Metals
EPA limit: 100 ppb (total chromium)
Copper
Heavy Metals
EPA limit: 1.3 mg/L (action level)
Radon
Radioactive Contaminants
EPA limit: No finalized MCL
Iron & Manganese
Minerals
EPA limit: 0.3 mg/L iron / 0.05 mg/L manganese (aesthetic SMCLs)
Atrazine
Agricultural Chemicals
EPA limit: 3 ppb (0.003 mg/L)
Uranium
Radioactive Contaminants
EPA limit: 30 µg/L (30 ppb)
Perchlorate
Industrial Chemicals
EPA limit: 0.056 mg/L (56 ppb)
VOCs
Industrial Chemicals
EPA limit: Varies by compound: benzene 5 ppb; TCE 5 ppb; PCE 5 ppb; vinyl chloride 2 ppb
Radium
Radioactive Contaminants
EPA limit: 5 pCi/L (combined Ra-226 + Ra-228)
Crypto & Giardia
Microbial Contamination
EPA limit: Zero (treatment technique standard)
Hydrogen Sulfide
Naturally Occurring Compounds
EPA limit: No MCL; Secondary MCL (aesthetic) of 0.05 mg/L
Selenium
Minerals
EPA limit: 50 ppb (0.05 mg/L)
Cadmium
Heavy Metals
EPA limit: 5 ppb (0.005 mg/L)
Mercury
Heavy Metals
EPA limit: 2 ppb (0.002 mg/L)
Barium
Heavy Metals
EPA limit: 2 mg/L
pH
Water Quality Indicators
EPA limit: 6.5–8.5 (secondary standard)
Find a Certified Lab in Arizona
Use the Arizona state-certified laboratory program to find accredited labs for private well testing. Always verify current certification before submitting samples.
AZ Certified Lab Directory ↗Arizona Well Water FAQs
Related Pages
Data Sources & Provenance
All data on this page is sourced from official U.S. government or public datasets.
Quick Reference
State program
AZ Certified Labs ↗EPA guidance
EPA Private Wells Program ↗State lab directory
AZ Certified Labs ↗Minimum Annual Tests
Plus state-specific contaminants listed above
Other State Guides