The Coastal Plain consists of sandy water-bearing units referred to as aquifers interlayered between non-water-bearing units. Wells constructed for domestic use range in depth from 15 feet to 500 feet. Yields are generally much greater than those obtained from the crystalline rocks of the Piedmont.

In the state of Delaware, well depths vary significantly depending on the local geology and the specific aquifer being accessed. In the northern part of the state (Piedmont region), domestic wells often reach depths of 100 to 300 feet to find water in fractured bedrock. In the central and southern regions (Coastal Plain), where the geology consists of layers of sand and gravel, wells can be shallower or much deeper; common domestic wells often range from 80 to 150 feet, while deeper agricultural or municipal wells can exceed 600 to 1,000 feet to reach confined aquifers with better water quality. Because the Coastal Plain aquifers are susceptible to saltwater intrusion and surface contamination, the Delaware Department of Natural Resources and Environmental Control (DNREC) often mandates specific depths for new wells to ensure a sustainable and safe water supply for residents.