reservoir

reservoir is a Noun

Definition:

[1] A place where anything is kept in store; especially, a place where water is collected and kept for use when wanted, as to supply a fountain, a canal, or a city by means of aqueducts, or to drive a mill wheel, or the like.

[2] A small intercellular space, often containing Receiving reservoir (Water Works), a principal reservoir into which an aqueduct or rising main delivers water, and from which a distributing reservoir draws its supply.