I live on the East Coast, where water supply is no problem. Does taking shorter showers make a difference, especially compared with fracking operations that use and contaminate millions of gallons of water?

—Brenda in Washington, D.C.

Just because fracking wastes water doesn't mean you should too. D.C. residents use 12 billion gallons a year. We don't know exactly how much water is squandered by fracking, but one EPA estimate puts it at 70 to 140 billion gallons a year at 35,000 U.S. sites. So you Washingtonians could be drawing as much water as 6,000 fracking wells do. While the East Coast is wet this year, in 1999 a drought in the mid-Atlantic region had wells running dry and D.C. talking about rationing. As for contamination, your water source, the Potomac River, is itself under constant threat from urban pollution and agricultural runoff. 

Also, there's a lot more to water than H2O. The EPA calculates that 3 to 4 percent of U.S. electricity is used to supply water and treat sewage. Finally, the average residential water bill in D.C. now exceeds $1,000 a year. So there are plenty of good reasons to conserve.—Bob Schildgen