The Green Challenge: CO2 meets H20.

Help the planet.
May 21 2007 12:37 PM

Water Works

CO2 meets H2O.

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• Instead of using hot water to thaw frozen food, let it defrost on the counter or in the refrigerator.

• An old water heater can operate for years at very low efficiency before it completely breaks down. If yours is more than 10 years old, it's likely running at less than 50 percent efficiency. Replace it with an energy-efficient one or, better yet, a heater without a tank, which warms up water only as you need it rather than holding hot water at the ready all the time. (Learn how to calculate how much hot water your household uses at peak times here. Learn more about water heaters here.)

• Insulating your hot-water heater is a cheap and easy way to make it more efficient. Most hardware stores carry water-heater blankets, which cost about $10 to $20 and can reduce heat loss by 25 percent to 45 percent. (Here's how to buy and install one.)

• Many hot-water heaters come factory preset at 140 degrees—hotter than you need. Reset your water heater's thermostat to 120 degrees Fahrenheit or lower and save yourself CO2 pounds (and a scalding).

• If you have a choice between using appliances run on natural gas or run on electricity, choose natural gas, which is generally cleaner in terms of CO2 emissions and also costs less.

• Solar water-heating systems can be used in any climate to heat your water supply. Since they use no fossil fuel energy, they save a lot of CO2 emissions. A typical household can meet 50 percent to 80 percent of its hot water needs using solar heat. Though they cost slightly more to install than a traditional system, your fuel source—the sun—is free. (Learn the basics on solar water-heating systems here. For more details, click here.)

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Meaghan O'Neill is a freelance writer and founding editor of, an eco-Web site and Slate's partner on the Green Challenge.