A household water audit is an assessment of how much water is used and how much water can be saved in a home. Conducting a water audit involves calculating water use and identifying simple ways for saving water in the home.
What are the benefits of conducting a water audit?
Conducting a water audit will make you aware of your water use and help you identify ways you can minimize water use.
How to calculate water useage in your home:
You can calculate your water use in one of three ways: from your monthly water bill, using your water meter, or by estimating your use manually.
Determine your average household usage, then compare your use to the average U.S. citzen's usage (animation below).
1. Calculating water use from your water bill.
If you receive your water from a utility, you can evaluate your water use from your monthly bill. Many bills provide average daily consumption during the billing period. If not, calculate the average daily use from the total monthly consumption by dividing the total monthly consumption by the number of days in the month.
Convert your average daily consumption to gallons using one of the following conversion factors:
cubic meters * 264 = gallons
cubic feet * 7.48 = gallons
liters * 0.264 = gallons
2. Calculating water use with a meter.
If your water bill does not provide water consumption data, then you can read your water meter to obtain this information. Water meters measure the total amount of water used in your home and are usually located at the property line or on the house. To obtain your water use over the course of a 24-hour period, read your meter at the same time on two consecutive days. You may want to measure water use for several days and then calculate a daily average. If needed, more information on reading water meters is provided by the Sustainability of semi-Arid Hydrology and Riparian Areas program at the University of Arizona.
3. Estimating water use without a meter.
If you do not have a water meter, you can estimate your water use. To determine how much water you consume in your home, it is necessary to measure water flow from each fixture in your house. Here are guidelines for various fixtures:
Faucets (indoor and outdoor)
Turn faucet to the normal flow rate that you use; hold a container under the tap for 10 seconds. Measure the quantity of water in the container. Multiply the measured quantity of water by 6 to calculate the flow rate in gallons per minute (gpm).
Toilets
Turn off the water supply to the toilet, mark the water line on the inside of the tank. Flush, then refill the tank with water from the tap, measuring the amount as you add it. Record the amount required to refill the tank. Turn water to the toilet back on and resume normal use.
Appliances
If your appliances are relatively new, you may be able to obtain the flow rate from the manufacturer's specifications. Otherwise, use the following averages:
Washing machine: 41 gallons/use
Dishwasher: 9 gallons/use
Next, measure how many times per day or how many minutes each day you use each fixture or appliance. Multiply the water flow per fixture by the minutes per day the fixture is used. Multiply the gallons per use for each appliance by the number of times the appliance is used each week. Don't forget to include outdoor water use. A useful spreadsheet to make these calculations has been made available by the Maryland Department of the Environment, Water Supply Program.
The following interactive tool allows you to compare your daily water use to that of the average United States citizen. Click anywhere on the tool to begin.
