Some tips to help you save:

Use a broom and bucket of water for washing down the patio rather than a steady flow of water from the hose.
Use mulch on the garden with help the soil retains water so will mean you won't have to water the garden as often.
Don't overuse hoses or sprinklers in hot weather. A sprinkler can use as much water in an hour as a family of four will use in a day. Your lawn only really needs watering once a week and it is better to water in the morning when the temperature is lower and evaporation is less.
Use a sponge and bucket of water to clean your car or if you use the hose, ensure you use a shut off nozzle so the water is not constantly running.
Leaking Pipes - If you have a water leak along a pipe and do not have the knowledge to fix it, call a plumber.