The watering schedule depends on the type of soil, sandy or clay, and whether the property is flat or on a slope.  If too much water is applied, nutrients will leach through the soil faster, taking them too far down for grass roots to reach them.  With too much water, grass won’t be as green, may lead to disease, and it will encourage weeds to thrive in that area.  Not enough water will cause grass to go dormant and turn brown, eventually leading to death.  Depending on the age and type of grass, sometimes grass can survive a drought.  In order for grass to survive a drought, nutrient and pH levels need to be optimum and grass needs a couple of years or more under its belt for the roots to get fully established.  So if you have fairly young lawn, make sure grass is taken care of during the summer months until roots are well established.