History of Gravity Fountains
Gravity fountains are not a new discovery. They date at least as far back as ancient Mesopotamian settlements from 4,000 BC, and operate on the same basic principal as the great aqueducts of ancient Rome. Water always seeks out the lowest point and flows toward that point as a result of the pull of gravity. The Romans used this principal to transport up to 250 gallons of water per person into the city each day. The water supplied the needs of the city's public baths, private homes and numerous gravity fountains.
Gravity Pulls Water Down
Gravity is the culprit that draws water to the lowest possible point, but defining exactly what gravity is can be a bit more daunting. Gravity is the force that attempts to pull matter together. Things with a lot of matter, such as the Earth, have a greater gravitational pull than things with less matter, such as water on the surface of the Earth. Since water is a liquid, it flows toward the source of the gravitational pull, which in terrestrial terms means the center of the Earth.
Air Pressure Pushes Water Up
Another principal of physics that drives a gravity fountain is air pressure. While gravity compels liquids to flow downward, it is air pressure that will force liquids upward, under certain circumstances. The pressure the atmosphere exerts on static fluids is the same, regardless of their horizontal level, provided the fluids are contained in connected vessels. The connected vessels of a gravity fountain may include on open reservoir, such as an open water tank or natural lake or pond, a connecting pipe and a fountain basin with a nozzle.
Elevated Water Source Needed
The source of your water supply must be at a higher elevation than the fountain outlet for a gravity fountain to operate. Gravity will draw the water down the connecting pipe toward the nozzle, while air pressure will seek to provide an equilibrium between the connected vessels. The water expelled from a vertical nozzle on a gravity fountain can reach a maximum height equal to the water level of the source in the open reservoir.