Real Simple answers your questions.
Q: My friend washes all her clothes in cold water to preserve the color. Do they really get clean this way?
A. Yes. The consensus is that cold water is more than up to the challenge of washing everyday laundry. “Technological advances, in both machines and detergents (not just the cold-specific kind), have made cold-water washing a highly effective option,” says Colorado-based clothing-care expert Steve Boorstein. Sometimes it’s safer than using hot water.
For example, protein stains (blood, sweat) can set in when washed in hot water, and hot water may shrink or wrinkle synthetic fabrics. That said, some people find that workout clothes still smell unpleasant after a cold cycle (synthetic materials, like those in some Under Armour and Nike Dri-FIT pieces, tend to hold on to bacteria and odor). If this is the case, do a cool-water prerinse within 20 minutes after your workout. This will help eliminate residual odor during the next cold load. Cold-water detergent is a good choice for gym wear; regular detergent works fine for other clothing.
Another argument for turning down the dial? Since about 90 percent of the energy consumed while running a load is used to heat the water, the average household opting for cold can eliminate as much as 350 pounds of carbon dioxide emissions annually. For most homes, this will amount to about $40 in savings a year.