Here's an easy way to measure how much water your lawn is getting: set empty coffee cans on the grass where they can catch water from your sprinkler. Check them periodically, and when one inch of water has collected, turn off the sprinkler. Make a note of how long it took for that one inch to accumulate and remember it for next time.

The best time of day to water is in the early morning when evaporation rates are low and grass can dry completely. If you water in the evenings, the grass doesn't have enough time to dry, and excess moisture makes the lawn susceptible to disease.

See our article on Choosing a Sprinkler for more information.