This encourages deeper rooting and makes your lawn healthier for the rest of the summer. Water the landscape only, not streets, walks and driveways. Keep grass fairly long - taller grass holds moisture better. This prevents the excessive shock that causes grass to turn yellow. Keep your grass two to three inches long.
Water is a precious commodity and there is a limited supply.
Remember to use only the amount you actually need. Look for ways to conserve water in and around your home and place of work.