A castle well[1] was a water well built to supply drinking water to a castle. It was often the most costly and time-consuming element in the building of a castle, and its construction time could span decades.
The well – as well as any available cisterns – provided a protected source of drinking water for the castle garrison in peace and war and also for any civil population seeking refuge during a siege. In medieval times, external wells were often poisoned, usually with a decomposing body, in order to force a garrison to surrender. But wells sunk within the castle itself could not be poisoned from outside during a siege.
- ^ The Medieval Castle: Romance and Reality Archived 2024-05-24 at the Wayback Machine ed. by Kathryn L. Reyerson, Faye Powe, p. 6. Retrieved 18 Nov 2013.