An aquifer was an underground layer of rock from which ground water could be extracted using a water well, though this water could also flow naturally from freshwater springs. Water found in aquifers was very cold. It was usually processed by an aquifer purifier before being distributed for consumption. Tap trees, whose tubular roots descended hundreds of feet underground, were sometimes used to siphon water from an aquifer, such as the thousand-year-old one on Sulon maintained by Morgan Katarn. Also, on Coruscant, water was gathered and stored in giant artificial aquifers.