If your home is on a private (domestic) well, you're responsible for the water quality. According to Arizona's Domestic Well Owner's Toolkit, private wells aren't regulated or monitored for water quality the way city systems are.1
Test for arsenic
Arsenic occurs naturally in Arizona groundwater. Arizona health guidance recommends testing a well before drinking or cooking with it, then testing periodically after that.2 The federal drinking water limit for arsenic is 10 ppb (0.010 mg/L).3 University of Arizona Extension has a dedicated guide to arsenic in private wells.4
Other things to test for
UA Extension's guide to Arizona well contaminants covers what to test for and how to read the results.3 Use a certified lab, and test before you buy any equipment.
Treatment
Pick a system based on your lab results. Hard well water often needs a softener, and RO is commonly used for drinking water. Several Tucson dealers list well water services; Desert Water Services, for example, installs systems for private wells.
Sources
- Arizona Domestic Well Owner's Toolkit
- Arizona Dept. of Health Services: arsenic in groundwater
- University of Arizona Extension: Arizona drinking water well contaminants (AZ1503)
- University of Arizona Extension: arsenic in private water wells
Last reviewed Oct 13, 2026. This is general information, not professional advice. Confirm figures with your utility and installer.