You can:
Turn off the faucet while brushing your teeth or shaving.
Wash only full loads of laundry.
Position sprinklers to water the lawn and garden, not the sidewalk or driveway.
Plant native shrubs and groundcovers rather than grass in your landscaping.
Allow your lawn to go dormant for a few months in the summer.
Compost food waste instead of using the garbage disposal.
Repair leaky faucets indoors and outdoors.
Install aerators on all your faucets.
Upgrade to more-water-efficient appliances, including toilets, showerheads, washing machines, refrigerators, and dishwashers.
Collect rainwater from your roof in rain barrels and reuse it to water your garden.
Rinse vegetables in a dish of water and then dump that water in your houseplants or garden.