To keep your lawn and grass healthy and green the lawn needs between 1 to 2 inches of water per week.
If it rains during some weeks then you do not need to water your lawn especially if it rains a lot during that week but if not you need to water your lawn for at least 30 minutes to an hour every few days or so of the week.
You can install lawn sprinklers that pop up and have them on timers so that they water the lawn when needed so that you keep your lawn healthy and green without needing to drag out regular lawn sprinklers.
Or you can also just use regular sprinklers and allow them to run 30 to 60 minutes each day to allow your lawn to get enough water.
Most home sprinkler systems use an average of 16 gallons of water per minute to water the lawn.
Larger sprinkler systems or commercial sprinkler systems may use an average of 50 to 100 gallons of water per minute and sometimes more depending on the size of lawn they are watering and how large of a sprinkler system they have.
The amount of water per minute also depends on the sprinkler head size and water pressure to those sprinkler heads.
But for home sprinkler systems that pop up out of the ground they use at most 16 gallons of water per minute of run time.
The longer you run them the more water you will use and in an hour of run time at 16 gallons per minute you would use 960 gallons of water.