Well Water Treatment in Arizona, New Mexico and Texas: Testing First

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In all three states, a private well's water quality is the owner's responsibility.

Arizona

Arizona's Domestic Well Owner's Toolkit says private wells aren't regulated or monitored for water quality.¹ Arsenic occurs naturally in Arizona groundwater, and state health guidance recommends testing before you drink the water, then periodically after that.² See our Arizona well water guide.

New Mexico

NMED's Drinking Water Bureau oversees public systems, and private wells fall outside its regulatory authority. Owners are responsible for testing and maintenance.³ NMED offers free screening of private domestic wells for nitrate, iron and fluoride. Private labs can do further analysis at the owner's expense.⁴

Texas

The Texas Groundwater Protection Committee says private wells are largely unregulated, with no state or federal requirement to monitor their water quality.⁵ It recommends annual testing for E. coli bacteria and nitrate-nitrogen.⁶ The Texas Well Owner Network (Texas A&M AgriLife) offers training and water screening events.⁷

Then choose treatment

Pick equipment that matches your lab results. HomeGuide puts well-water filtration systems at $800–$4,000 installed.⁸ Hard well water often needs a softener, and RO is common for drinking water (softener vs. RO).

Sources

1. Arizona Domestic Well Owner's Toolkit
2. Arizona Dept. of Health Services: arsenic in groundwater
3. New Mexico Environment Department: private wells
4. NMED: free well water testing
5. Texas Groundwater Protection Committee: private wells
6. TGPC: what property owners should know about their water well (FAQ)
7. Texas Well Owner Network (Texas A&M AgriLife)
8. HomeGuide: home water filtration system cost (2026)

Last reviewed Oct 13, 2026. This is general information, not professional advice. Confirm figures with your utility and installer.