State Well Water Guide
New Mexico Private Well Water Guide
Approximately 15% of New Mexico residents — about 300,000 people — rely on private wells and small systems. New Mexico's arid geology creates a distinct contamination profile dominated by naturally occurring contaminants: arsenic is widespread in volcanic and basin geology across the state, uranium is naturally elevated in sandstone aquifers in the Grants Mineral Belt and eastern New Mexico, and fluoride exceeds recommended levels in some southwestern aquifers. The state also has significant legacy uranium mining contamination on the Navajo Nation and in the Grants Belt, affecting both private wells and small community systems. The New Mexico Environment Department (NMED) oversees well construction but private domestic wells are exempt from ongoing regulatory monitoring.
Testing Guidance
The NMED and New Mexico State University Extension recommend annual bacteria testing and arsenic and uranium screening at least every 3 years for all private wells. Arsenic testing is critical across the Rio Grande Rift basin, Jemez volcanic field, and southeastern basins. Uranium testing is essential for wells in Cibola, McKinley, and San Juan counties near the Grants Uranium Belt. PFAS testing is recommended for wells near Kirtland AFB, Cannon AFB, Holloman AFB, and White Sands Missile Range. Nitrate testing is important for wells near the Rio Grande agricultural corridor.
What to Test For in New Mexico
Total coliform bacteria and E. coli — annual minimum for all wells
Arsenic — all New Mexico wells; the state has among the highest natural arsenic in the U.S.
Uranium — wells in Cibola, McKinley, Valencia, and Sandoval counties near the Grants Mineral Belt
Fluoride — southwestern New Mexico; naturally elevated in some aquifers
Nitrates — Rio Grande agricultural corridor and wells near septic systems
PFAS — wells near Kirtland AFB, Cannon AFB, Holloman AFB, and White Sands Missile Range
Radium — some eastern New Mexico oil and gas production areas
Total dissolved solids (TDS) — New Mexico groundwater is often highly mineralized
Common Contamination Risks in New Mexico
Naturally occurring arsenic — New Mexico's volcanic, basalt, and basin sediment geology is among the highest-arsenic groundwater environments in the country
Uranium from mining legacy and natural occurrence — the Grants Mineral Belt is one of the largest uranium mining districts in U.S. history; contamination affects both Navajo Nation wells and non-tribal communities
Elevated fluoride in some aquifer systems — dental fluorosis and at very high levels skeletal fluorosis
PFAS plumes from multiple military installations across the state
High TDS and salinity — New Mexico's arid groundwater often has TDS well above 500 mg/L, affecting taste and requiring treatment for some uses
Contaminant Guides Relevant to NM 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 New Mexico
Use the New Mexico state-certified laboratory program to find accredited labs for private well testing. Always verify current certification before submitting samples.
NM Certified Lab Directory ↗New Mexico 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
NM Certified Labs ↗EPA guidance
EPA Private Wells Program ↗State lab directory
NM Certified Labs ↗Minimum Annual Tests
Plus state-specific contaminants listed above
Other State Guides