Water longer but less often
Ths method - commonly referred to as cycle and soak - applies water slowly so the soil actually absorbs all that is applied. Instead of setting the sprinkler to run for 15 to 20 minutes, run each zone only the amount of time needed so that the soil can absorb the water. Depending on the slope of the yard, this could vary widely from zone to zone. You will have to test your run zone times to see when the water begins to run off.
Once you have determined the maximum amount of water each zone can take before runoff, split the total irrigation time into two or three parts. This will involve irrigating the zone, shutting it off to allow time for the water to soak in, and then irrigating the reaminder of the time. Schedule the run times about one hour apart until the soil is moistened to a depth of six to eight inches. Most sprinkler system controllers can be programmed to automatically run the cycle and soak method.
The lawn has been successfully watered when about an after watering, push a soil probde (or long screwdriver) into the soil. It will easily slide through wet soil but will be impossible to push through dry clay soil. The probe should be able to slide into the soil to a depth of six to eight inches.