Grow grass appropriately. Don't mow your lawn too short. Raise the height of your mower blade, or simply let it grow a bit longer between mowing. This way you won't have to use as much water.
Grow no grass or less grass. Plant something besides a lawn or reduce the size of your lawn. Lawns require much more water (and maintenance) to keep growing than many other plants and ground covers.
If you live in an area with infrequent rain, consider not planting grass and instead using plants from your area that don't need as much attention and water.