Which of the following wells is considered the most dependable source of water and is less likely to become contaminated?

A drilled well is considered the most dependable source of water primarily due to its construction and depth. Drilled wells are typically constructed using a rotary drilling technique that allows for deep penetration into aquifers, which can provide a more stable and reliable supply of water.

Being deeper, drilled wells often access groundwater that is less susceptible to surface contamination compared to shallow wells. The process of drilling creates a borehole that is lined with casing material, which provides an additional barrier against contaminants entering the water supply. Additionally, the design of drilled wells allows for effective sealing to minimize the risk of contamination from surface runoff, animals, or existing pollutants.

In contrast, driven wells, bored wells, and dug wells typically reach shallower water sources or are less protected against surface contamination. Driven wells, while useful, can be less reliable in terms of water quality due to their shallow depth. Bored wells and dug wells are even more susceptible to contamination as they can expose the water supply to surface water and soil pollutants, making them the least dependable options for a safe water supply.