How many inches should a well casing extend above the ground surface?

A well casing should extend above the ground surface by 6 to 12 inches to help ensure proper drainage away from the well and to protect it from surface contaminants. This height provides a barrier against runoff, which can carry sediment, chemicals, and pathogens toward the well. Additionally, an adequate height helps prevent animals or debris from entering the well system, maintaining the well's water quality.

The specified range of 6 to 12 inches is a common standard recommended by various health and safety guidelines. It strikes a balance between being high enough to provide necessary protection while not being excessively tall, which could pose an obstacle in the surrounding area.

The other options suggest heights that either do not provide sufficient protection (2 to 4 inches) or are excessive and impractical for typical well configurations (10 to 15 inches or 1 to 3 inches), hindering the well's effectiveness and leading to potential contamination risks.