A water feature is a man-made construction whose principal feature is moving water. The motion of the water can be propelled or it can be a simple flow from one level to another. Groups of related water features are generally classified as a single object, so that it can consist of several parts spread over a wide area.

Only outdoor water features are listed as separate structures. If moving water is a component of a sculpture or a monument, then the whole structure may be classified as a water feature, especially if its name indicates the importance of the water element (e.g. if it is called a "fountain"). If a water feature is decidedly subordinate to another purpose, then the structure is classified by that purpose.

The display can consist of several related parts rather than one compact construction. Water must remain the principal feature; a minor water element does not override another dominant purpose.