SCORCHED EARTH: Water often gets wasted where it is, which may leave once-wet places high and dry.
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Many of us use water thoughtlessly; it seems as abundant as the air we breathe and a free swig is available almost anywhere. But fresh, potable water is already a precious commodity in many drier parts of the world, and as it grows rarer—and thus, dearer—in developed countries, the true value of H2O is beginning to seep in.

Until water shortages impact more of us directly it is likely that this liquid resource will continue to be poorly managed. Whether it's the inefficient flooding of farm fields or hosing down our cars every weekend, people find many ways to waste water.

The recent story of a profligate user who changed his ways could perhaps serve as an example for us all: Saving water often comes down to paying attention. Although Atlanta recently suffered its worst drought in a century, the local estate of wealthy investor Chris G. Carlos consumed 440,000 gallons (1.67 million liters) in September 2007 alone. After a public outcry, Carlos dramatically reduced his monthly usage to just 12,000 (45,400 liters)—about what an average U.S. family of four expends during the same time period.

Although that's an extreme case, it shows that there's often little reason why we can't save more water in our day-to-day lives. Here's a list of some of the more egregious ways in which we squander it; some are easily avoidable, whereas others will require big changes in agricultural and industrial practices.

1. Doing the Dishes: By Hand or Dishwasher?
A lot depends on your dishwashing style: A typical session that includes turning the water on and off will go through about 20 gallons (75 liters) or so. But if you leave the water running while scraping at those last grisly bits on your fine china, you may use more than twice that amount. Modern electric dishwashers, in contrast, need less than 10 gallons (38 liters) per average load, says a survey by the American Water Works Association.

2. Washing the Car (and the Driveway)
Wear that bathing suit at the pool or the beach, but not for posing in the driveway while sluicing the suds off your auto with hose water. According to Kaady Car Washes, a west coast chain, a home car wash can go through 80 to 140 gallons (300 to 530 liters) of water, whereas a wash at one of its garages will take about 30 to 45 gallons (115 to 170 liters). Professional car washes also utilize methods that recycle water: The U.S. Environmental Protection Agency mandates that wastewater be channeled to treatment plants to avoid polluting the environment; contaminated water from your home car cleansing just flows into street drains or leaches into the soil.

3. Slipping Through the (Pool) Cracks
Cannonballs aside, a swimming pool naturally loses about 1,000 gallons (3,785 liters) a month to evaporation, according to the Maui County, Hawaii, Department of Water Supply, although the local climate and the pool's overall surface area determines the amount that's actually lost. A bigger problem arises from the leaks that pools often develop during their lifetimes from cracks in their foundations, liner tears and pipe damage. Estimates vary wildly, depending on everything from a region's temperature fluctuations to seismic activity. National Leak Detection (pdf), a company based in Mesa, Ariz., puts the figure at a whopping 30 percent. Three hundred miles (480 kilometers) west in Palm Springs, Calif., American Leak Detection, Inc., puts the pool leak rate at a more conservative one in 20. Either way, because most pools have automatic refillers, owners often fail to notice the loss until their next water bill arrives.