All this water comes from a huge, water-saturated rock. Florida is literally a rock sponge. Lying just beneath its sandy topsoil is an enormous, limestone basin called the Floridan Aquifer, which descends from Alabama, Georgia and South Carolina. For their households and industries, these states, along with Florida, pump more than 8 billion gallons of water a day from this vast underground pool.

Occasionally, too much water builds up at random places throughout this great well. When this happens, pressure pushes it up through a crack in the ground above it, bringing water shooting into the sunshine.

An estimated 700 or so springs bubble to the surface in Florida. Some are tiny, emerald jewels tucked into remote woodlands, known only to a few. Others are giants.

Florida has 33 of these mammoth springs which hydrologists call “first magnitude.” To be classed as such, a spring must produce at least 100 cubic feet of water a second, or roughly 65 million gallons of water a day. Florida is home to more of these mighty springs than any other state-or country, for that matter. The combined outflow of these huge springs is estimated at more than 8 billion gallons a day.

Water purling up from these springs is uncommonly clear and clean, laundered by layers of sand and rock that filter out organic matter, bacteria and other contaminants. Geologists say the longer water percolates in limestone the clearer it gets.

“In the deeper springs like Wakulla, although the average age of the water is 20 years, there's water in the mix that's been underground for centuries,” said Brian Katz, a springs expert with the U.S. Geological Survey.

In Florida, with the water table so close to the surface, almost anything that falls onto the ground eventually makes it way into the aquifer where it threatens pristine, often ancient water. The more Floridians there are, the more polluting chemicals-such as nitrate compounds-hit the ground and threaten the quality of this one-of-kind system. “We've found that the older the water is (in the aquifer) the fewer nitrates are in it,” said Katz. “When you find water that's 50 or 60 years old, there are hardly any nitrates present.”