Well Water in Sedona / Verde Valley, Arizona
Yavapai County · Population ~40,000 (Verde Valley) · Aquifer: Verde River Basin Alluvial and Sedimentary Aquifers
Hardness: Moderate to Hard
The Verde Valley's red rock geology is more than scenic — the Supai Formation and associated sedimentary rocks that create Sedona's famous landscape also influence groundwater chemistry. Arizona Water Company serves Sedona from local groundwater wells, and the water meets all standards. But private wells in the valley face arsenic from the volcanic and sedimentary geology, nitrate from the thousands of septic systems in the watershed, and the increasing challenge of supporting a growing population on limited groundwater.
Geology and Water Chemistry
Sedona and the Verde Valley sit in a geological transition zone. The red rock formations — Supai Group, Coconino Sandstone, and the underlying Verde Formation (ancient lake sediments) — create a complex hydrogeological environment.
The Verde Formation in particular contains evaporite deposits — ancient salt and mineral concentrations from a lake that existed millions of years ago. Where groundwater contacts these deposits, it picks up dissolved minerals, contributing to hardness and elevated TDS.
The volcanic geology surrounding the valley (the Mingus Mountain/Black Hills area) contributes arsenic to groundwater. Arsenic-bearing minerals in volcanic and granitic rocks dissolve slowly into the aquifer system over time.
Septic Systems and Nitrate
Much of the Verde Valley, including parts of Sedona, relies on septic systems rather than centralized sewer service. Thousands of septic systems discharge treated effluent into the shallow subsurface, and in areas with permeable geology, nitrate from these systems reaches groundwater.
The EWG Tap Water Database flags nitrate/nitrite as a contaminant of concern in Sedona's water system. Sources include fertilizer runoff, septic tanks, and urban runoff. For private wells — which are typically shallower than municipal wells — the risk of septic-derived nitrate is higher.
If you're on a private well in an area with dense residential development served by septic systems, annual nitrate testing is important.
Emerging Contaminants
A 2014 study tested for contaminants of emerging concern (CECs) in Sedona's water supply and Oak Creek. Arizona Water Company's wells tested clean for CECs. In Oak Creek itself, only DEET (insect repellent ingredient) was detected.
Chromium (hexavalent) has been flagged in Sedona's water data — it may be naturally occurring from mineral deposits or have industrial origins. Long-term exposure is a health concern.
ADEQ completed a Source Water Assessment of Arizona Water Company's Sedona wells in 2004, finding low risk to seven water sources but high risk to one source from adjacent land use.
Testing Recommendations
Verde Valley well owners should test for:
- Arsenic — given the volcanic and sedimentary geology
- Nitrate — especially in areas with dense septic systems
- Bacteria — annually, particularly in shallow wells
- Hardness, TDS, fluoride — baseline mineral panel, given the evaporite-bearing geology
See our testing guide for labs and costs.
Every well is different. Two wells on the same street can produce completely different water. The data on this page reflects documented conditions in the Sedona / Verde Valley area, but the only way to know what's in your water is to test it.
Sources
- ADEQ — Source Water Assessment, Arizona Water Company Sedona System
- Arizona Water Company — 2024 Annual Water Quality Report for Sedona
- EWG Tap Water Database — Arizona Water Company Sedona
- USGS — Verde River Basin Groundwater Studies