A well was typically a hole dug to a water source such as a spring. A Vurosis got into a well in Creighton Mere and waited, its brain elsewhere. (PROSE: Wishing Well)
When the Doctor got thirsty in medieval times, he had his friend Bors and the peasants of the area to dig a well in multiple different areas. (TV: The Doctor's Meditation)
While dining with Clara Oswald, Danny Pink became defensive about his time as a soldier, emphasising his humanitarian work, which included digging twenty-three wells. (TV: Listen)