Bathroom
Your bathroom is a key place where you can unknowingly waste water. Using an older toilet can be costing you water. Toilets purchased before 1994 used 3.5 gallons for every flush. Today's "low-flow" toilets use only 1.6 gallons. Typical showerheads feature flows of 3 gallons per minute. Replacing them with water-efficient heads can reduce that flow to as little as 1 gallon per minute -- saving as much as 30 gallons during a 10-minute shower. If you are running the water while brushing your teeth and shaving, then you could be wasting as much as 300 gallons a month.
Kitchen and Laundry Room
If you allow your water to run while washing dishes, then you are wasting water. A better solution is to fill one side with soapy water and the other with rinse water. Operating your dishwasher for small loads is another waste of water -- only wash full loads. Rather than grabbing a new glass for every drink, reusing your glass can cut down on the amount of dishes that you wash. Washing laundry in a washer that cannot adjust the water level for load size is another source of wasted water. Consider upgrading to a high-efficiency washer. They not only adjust for load size, but use far less water.
Yard
The primary source for wasted water in your yard is irrigation. If your sprinklers are watering the side of your house, sidewalk or street, then you are wasting all that water. Furthermore, if you are using an automated sprinkler system, you could be wasting even more. Only water your yard when the soil actually needs it. When you water the grass is just as important. Watering during the the hottest part of the day is a major source of wasted water. Instead, water during morning or evening hours. Washing your car in the driveway sends all your water down the street and into a storm drain. Consider washing it on your grass and kill two birds with one stone.
Maintenance and Repairs
Not performing regular maintenance and repairs can result in a lot of wasted water. One leaky faucet alone can waste up to 140 gallons a week. If you have a leaky toilet, then you are wasting as much as 1,000 gallons per month. Listen for running toilets or use food coloring in the tank to check for leaks. If you have not installed aerators on your faucets, then you are wasting water. These devices mix air with the water, reducing the amount of water flowing out of the faucet. Every faucet aerator can save as much as 280 gallons of water per month.