Do Deeper Wells Mean Better Water?

How deep should a well be? When is a well considered “deep”? Do deeper wells always provide better quality water? This publication answers these questions to help you understand the differences in water quality that can occur between shallow and deep wells. You’ll learn where the water in your well originates. You’ll discover that a “shallow well” in one location might be a “deep well” in another part of the county or state. And you’ll learn why, in some cases, a shallow well is actually a better choice than a deep well. The information presented here focuses on domestic wells that draw water from two sources in Arizona: (1) the Basin and Range aquifers located in southern Arizona (which generally consist of unconsolidated (loose accumulations of) gravel, sand, silt, and clays) (USGS) and (2) the Colorado Plateaus aquifers in northeastern Arizona (these aquifers are composed of permeable sedimentary rocks like sandstone, siltstone, and shale) (USGS). Groundwater in the Basin and Range aquifers is found in pore spaces between the soil particles. However, groundwater in the Colorado Plateaus aquifers is found in the fractures within the rock.