Water storage facilities are places for bulk storage of water for any purpose. It may be used for drinking, cleaning, cooking, manufacturing, agriculture, as a fire retardant, or for any other purpose. It may be cleaned or pure, heated, chilled, or stored at ambient temperature. This does not include warehouse storage of packaged water. It can apply to an open reservoir or artificial pond, although not to the dam which forms it.

Water can be held at different temperatures and levels of purity. A drinking-water supply is one included purpose, alongside industrial, agricultural, and other uses.

An open reservoir or artificial pond can be the storage site. The dam retaining the water is a separate structure and is not itself the stored-water usage.