Before the 18th century they were usually powered by gravity, though the famous Hanging Gardens of Babylon are described by Strabo as supplied by an Archimedean screw. Other examples were supplied with water using hydraulic rams.
Since the 18th century, the majority of water features have been powered by pumps. In the past, the power source was sometimes a steam engine, but in modern features it is almost always powered by electricity. There is an increasing range of innovative designs as the market becomes more established and people become more aware of alternate installation methods, such as solar power. The advantages of using solar power include environmental benefits, no electrical lines in the garden, and free energy.
Modern water features are typically self-contained, meaning that they do not require water to be plumbed in; rather water is recycled from either a pond or a hidden reservoir, also known as a sump. The sump can either be contained within the water feature, or buried underground (in the case of an outdoor water feature).
A water feature may be indoor or outdoor and can be any size, from a desk top water fountain to a large indoor waterfall that covers an entire wall in a large commercial building, and can be made from any number of materials, including stone, granite, stainless steel, resin, and glass. Most water features are electronically controlled, ranging from simple timer actuators to sophisticated computerized controls for synchronizing music to water and light animation.
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