The U.S. Environmental Protection Agency estimates that half of the water applied to residential yards is lost to overwatering, evaporation, and wind. The best way to avoid this waste is to water your lawn less frequently, but with deeper penetration. Watering just once or twice a week can be sufficient if you water early enough in the morning to avoid evaporation from the sun and wind. Note that watering in the evening can result in mold and lawn disease, so make sure you water in the morning.