A well casing should extend above the ground surface by how many inches?

A well casing should extend above the ground surface by 6 to 12 inches to prevent surface water from entering the well and contaminating the groundwater supply. This elevation is crucial for protecting the well from surface runoff, which could carry pollutants into the well system. The specified height also helps to ensure that the well remains accessible for maintenance, while minimizing the risk of flooding or debris entering the well. Maintaining this height is part of good well construction practices and is often regulated by various health and safety standards to promote safe drinking water. The other choices either exceed this recommended height or fall short, which could compromise the well's integrity and safety.