Facts of the Matter
Drinking water less plentiful than it seems
With 70 percent of the planet covered by water, it is too easy to think that water is easily accessible and plentiful. It is both, but not clean, potable water. A little more than 97 percent of Earth's water is in the oceans, too saline to drink.
Surface water near populated areas is typically contaminated with sediment, industrial, human or animal waste and must be purified to be potable, and purification requires expensive filtration and chemicals.
Freshwater lakes and streams account for only nine ten-thousandths of 1 percent of all of Earth's water. This is half a million gallons for every human on Earth, but like other resources the use is not evenly distributed across all socioeconomic levels.
The problem is not the amount of fresh water; it is getting it in potable form to where people are.
Much of the world's population lives in arid regions where rainfall is sparse and there are no perpetual streams. Ground water is plentiful but often lies far below the surface and requires technology to drill deep wells and energy-hungry pumps to draw it to the surface.
Civilization is built on water. Ancient Egypt flourished only due to the regular flooding of the Nile. Two thousand years later, Roman engineers built a series of 11 aqueducts that provided well more than a million people 300 gallons of water per person per day. This is as much if not more than we are accustomed to for personal use today.
We use much more than just our household water. Fresh water used for industrial and energy production adds another 1,200 gallons per day per capita.
Aqueducts were perfected in ancient Rome, but they are still responsible for the water supply of America's two largest cities, New York and Los Angeles, which serve as examples of the interface of increased population and land development with water resources.
New York City draws its water through aqueducts from a system of 19 reservoirs and controlled lakes that cover a watershed of more than 1,900 square miles. Ninety percent comes from as far away as 120 miles in the Catskill Mountains.
Although it comprises the largest unfiltered water system in the country, in recent years it has become muddied due to changing weather patterns and increasing runoff from land development.
To avoid building an $8 billion filtration plant, the city dumps 16 tons of chemicals daily into the water to meet federal quality standards. But it might not be able to hold out for much longer.
The water supply of Los Angeles has even more diverse sources. Water comes from the Sierra Nevada, Mono Lake Owens Valley, the Colorado River and local ground water through more than 7,000 miles of pipe. Reduced supplies from Mono Lake and Owens Valley are forcing officials to seek new water sources.
Desalinization of sea water will no doubt be the future supply of large amounts of fresh water, and engineers are working to increase the efficiency of systems.
There are always droughts occurring somewhere in the world, which ought to remind us that pure water appears by technology, not by magic, when we turn on the faucet.
Richard Brill, professor of science at Honolulu Community College, teaches earth and physical science and investigates life and the universe. E-mail questions and comments to firstname.lastname@example.org