Well Water in Queen Creek / San Tan Valley, Arizona
Maricopa / Pinal County · Population ~150,000 · Aquifer: East Salt River Valley Sub-Basin
Hardness: Very Hard (up to 25+ grains per gallon)
Queen Creek and San Tan Valley sit on ancient alluvial deposits where deep groundwater has filtered through limestone, caliche, and mineral-rich desert soils for thousands of years. The result is some of the hardest water in Arizona. Rapid growth — the area has exploded from a few thousand residents to over 100,000 in two decades — puts increasing pressure on groundwater resources. Legacy agricultural contamination including DBCP (a banned pesticide) persists in the aquifer.
Extreme Water Hardness
The East Valley's geological foundation — ancient alluvial deposits and sedimentary rock formations — naturally loads groundwater with dissolved calcium and magnesium. Queen Creek draws from deep groundwater aquifers, and the mineral content is substantial.
Water hardness in this area commonly exceeds 15-25 grains per gallon, classified as "very hard." For comparison, anything above 10.5 GPG is considered very hard. This creates visible problems: scale buildup in pipes, reduced soap effectiveness, spotting on fixtures, and shortened appliance lifespan.
Hardness isn't a health hazard, but it affects quality of life and costs money through damaged plumbing and appliances. A water softener is the standard treatment.
Agricultural Legacy Contamination
The Queen Creek/San Tan Valley area was agricultural land for decades before residential development. That history left contaminants in the aquifer:
- DBCP (1,2-Dibromo-3-chloropropane) — a banned soil fumigant once widely used in Arizona agriculture. It persists in groundwater for decades. DBCP is a probable carcinogen and reproductive toxin.
- Nitrate — from fertilizer application and agricultural runoff. Elevated levels continue to appear in groundwater long after farming stops.
The transition from farm to suburb doesn't erase what's in the aquifer. Wells drilled into formerly agricultural land may encounter legacy contamination that predates the neighborhood.
Other Contaminants
Testing data from the Queen Creek water system and the EWG Tap Water Database show detections of:
- Chromium (hexavalent) — a carcinogen that may be naturally occurring from local geology or from industrial sources
- Arsenic — naturally occurring in the basin-fill aquifer
- Fluoride — present at varying levels
- Barium — naturally occurring in sedimentary formations
Public water systems treat and blend to meet standards. Private well owners get raw, untreated groundwater.
Growth Pressure on Groundwater
Queen Creek and San Tan Valley are among Arizona's fastest-growing communities. The Town of Queen Creek operates 14 active drinking water wells. San Tan Valley's water infrastructure has been built almost entirely in the last two decades.
Rapid growth means more wells, more pumping, and increased risk that water quality will change as the aquifer is stressed. For private well owners, this means conditions at your well may not be stable — what tested clean five years ago may test differently today.
Test your water regularly and pay attention to changes. See our testing guide for labs serving the East Valley.
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 Queen Creek / San Tan Valley area, but the only way to know what's in your water is to test it.
Sources
- Town of Queen Creek — Water Quality Reports
- EWG Tap Water Database — Town of Queen Creek
- ADEQ — Groundwater Quality in Arizona: A 15-Year Overview
- AZDHS — Water Quality Data for Exempt Wells in Arizona