Place a small can on your lawn and time how ling it takes to get ½” of water in it from your sprinklers. This is the longest time you would need to water on each of two or three days a week during the hottest part of the summer.
Lawns with clay soils usually grow well being watered only twice a week for 30-60 minutes. Sandy soils may need to be watered on an additional day. Too much water can damage lawns and crops.
Water usage by lawns and gardens is substantially less in the spring and the fall than it is in July and August. Don’t forget to change your routine or your automatic sprinklers accordingly.