Avoid letting the faucet run. Rinse your razor in a sink of water. Letting the water run uses about three gallons per minute. Check faucets and pipes for leaks. A small drip from a worn washer can waste 20 or more gallons a day.
Larger leaks waste even more.
Turn the dishwasher on only when full. Avoid washing dishes under running water. Wash your dishes only once a day. Buy and install a faucet aerator. Keep a bottle of drinking water in the refrigerator.