Check your water flow. If it is tight, design a garden of low water consumption.
Reduce the turf, which is who consumes more water in a garden.
Choose drought resistant plants; there are many who live almost without irrigation, for example, indigenous and originating in desert areas.
Protect the garden from the wind; it dries the soil. Also create sun shade.
Arrange padded at the base of plants: pine bark, mulch, gravel or straw. This prevents evaporation and weeds.
If you water your plants soon get used to the lack of water and develop deeper roots for moisture.
Design your garden by making use of drought resistant species which spends less turf surface or replace it with a green cover to cover plants as Gazania, Ivy, Lampranthus, or Vinca.