Rules of Thumb for Water Use on Lawns

How much water does a lawn need? In general, turf grasses need about 3/4 to 1 inch of water per week to maintain green color and active growth. However, during certain times in the summer when high temperatures are the norm, you should allow lawns to naturally slow down in growth. You can let the lawn go almost completely dormant in hot weather. In hot weather you may need an inch of water only about every three days.
In general, water as infrequently as possible. When you do water, water thoroughly so that moisture soaks down to the roots. One deep watering is much better than watering several times lightly. Watering to a depth of 4 to 6 inches encourages deeper, healthier root development. It also allows longer periods between watering. Early morning or night is the best time for watering, as less evaporation will occur at these cooler times.