What depth defines a shallow well?

A shallow well is typically defined based on its depth in relation to the groundwater aquifers it taps into. In general, shallow wells are those that access groundwater at depths of 25 feet or less, which is why the depth of 25 feet or less is appropriate to classify a well as shallow.

This definition aligns with the typical characteristics of shallow wells, which draw from more accessible aquifers and are usually less expensive and easier to drill compared to deeper wells. Wells deeper than this are generally classified as deep wells, which can access water from deeper aquifers that may require different construction techniques and have distinct water quality considerations.

In the context of the provided options, selecting the depth of 25 feet or less accurately reflects the standard definition for shallow wells, making it the correct choice for this question.