San Francisco wins the title of America's "least wasteful" city, followed by Seattle, New York, Portland, Ore., and Boston, according to a survey of the 25 largest cities.

The rankings are based on 23 weighted questions that 3,750 people in these cities answered about their living habits, from recycling to using public transportation to turning off the lights when they leave a room.

"Overall, Americans living in the country's largest cities are making slight improvements to be less wasteful," finds the second annual survey, conducted by research firm Greenfield Online, for Nalgene, a company that produces BPA-free bottles.

As the 40th anniversary of Earth Day approaches this Thursday, the survey aims to raising awareness about how simple measures can reduce waste and pollution.

The most wasteful U.S. city? Houston, followed by Cleveland, Atlanta, Tampa and Indianapolis.