Newly planted sod
With newly planted sod, water heavily for 7 to 10 days at any time of day and then scale your watering down.  “Watering heavily” means watering to the point of saturation.  This could mean as many as 20 - 30 minutes per station, two (or even three) times a day.  Reduce this time if you see runoff, but water to this point.  If it is drying out before sunset, add an additional cycle.  You cannot overwater new sod during this 7 - 10 day period.   After this time period, follow the watering guidelines for established lawns, which are listed below.

Established lawns
Once your lawn is established, scale your watering down.  To train the roots to go deeper (and thus become more winter hardy and drought resistant), do not water blindly on a rigid schedule.   Hold off watering your grass until a slight wilt is detected in the foliage, then give it two consecutive days of heavy watering.  Taking your sprinkler system off the timer and following these instructions will strengthen your grass while lowering your water bills. 

By visually inspecting and adjusting each station of your sprinkler system, you can avoid both grass problems and water waste.  Some stations will require more time or less time than others.  Water each station until runoff is seen.  Then, back the station off by a few minutes.

Water your lawn only in the morning, not in the evening.  Your municipality may be under watering restrictions due to drought conditions.  Contact your city water department to find out when you are allowed to water.