On your watering day, turn off other household water usage and take a reading of the water meter. Turn on your sprinkler system and let it run through a complete cycle for all zones and take another meter reading. The difference in readings will tell you how much water was used. Typical irrigation systems use between 10 and 20 gallons a minute. During the growing season, set your mower blades a little higher.
Taller grass retains moisture better than short grass.
For landscape plants, such as foundation plantings, one of the best methods of keeping them healthy and saving water is to install a low volume system around the plants. However, these cannot be used for lawn grass. When you pick your landscaping materials, try to pick those that are natives and are drought-tolerant. Another way to lower water use is to reduce the amount of lawn area by installing paths, other landscaping plants, decks or patios, or Xeriscaping. Numerous books and pamphlets explain these subjects in detail.