The rule of thumb for watering lawns is 1/2 inch, twice per week. There are some variables however. If we have very dry weather patterns, plan to add a watering. Very light, sandy soil drains more quickly than heavier soils so an additional watering would be appropriate. Also – take rainfall into account.
How long should I let my sprinklers or watering system run in order to get a 1/2 inch of water on my lawn?
Time is dependent on water pressure so there is really no set length of time to leave your sprinklers or system running. Put a rain gauge about half way between your sprinkler and the end of the arch the water stream reaches. Check the rain gauge periodically and when you find 1/2 inch of water in the gauge note how long the system has been running. You now know how long to water each area of your lawn.