The USGS Water Science School
Water Science water-use pages
Categories of Use:
National Water Use Program
Information and Data
Public-supply water use
No doubt the first public-supply water system was when Jack the Caveman was hired by his neighbors to fetch a bucket of water from Dinosaur River in exchange for some delicious prehistoric bran muffins. If you read our fictional tale about starting a new town in the desert, you'll see that even in a town with a population of one person, a plan to get, use, and dispose of water is always needed. Public and private water-supply organizations that get water, clean it and deliver it to local residents exist anywhere people exist.
Public water-supply systems, which you might know better as the county and city water departments, are vitally important to all populations. These are government or privately-run facilities that withdraw water from rivers, lakes, reservoirs, and wells and then deliver it to our homes, businesses, and schools. The majority of the population (about 86 percent) of the United States nowadays gets their water in this manner. You probably get your home drinking water this way. In the past, when the population was a lot more rural, people used to have to dig their own wells and create storage tanks for their water supply. But with large numbers of people living in bigger cities the public-supply systems do that work for us. All we do is turn on the tap ...oh, and pay the bills.
For this site, public supply refers to water withdrawn by public and private water suppliers that provide water to at least 25 people or have a minimum of 15 connections. Public-supply water is delivered to users for domestic, commercial, and industrial purposes, and also is used for public services and system losses.
Public-supply withdrawals for the Nation, 2005
Approximately 44,200 million gallons per day (Mgal/d) of water was withdrawn for public supply in 2005 with 66 percent of that coming from surface-water sources. (All 2010 water use information is from the report Estimated use of water in the United States in 2010.) This amount is 2 percent more than the estimated amount of water withdrawn for public supply in 2000. Public supply represents about 13 percent of total freshwater withdrawals, and 21 percent of all withdrawals, not including thermoelectric power. Some public-supply water sources are desalinated seawater or brackish groundwater that has been treated to reduce dissolved solids. These saline water sources currently represent a relatively small proportion of total public-supply water withdrawals in the United States.
Public-supply withdrawals, by State, 2005
As time has gone by, more and more people have been served by the Nation's water departments. In 2005, about 258 million people of the Nation's total population of 301 million were served in this manner. The map below shows the amount of public-supply withdrawals by State for 2005.
Data table: Public-supply water withdrawals by state, 2005 (PDF)
An estimated 258 million people relied on public water supplies for their household use. This number represents about 86 percent of the total U.S. population. States with the largest populations (California, Texas, New York, and Florida) withdrew the largest amounts of water for public supply. Two-thirds of water withdrawn for public supply in 2005 was from surface sources, such as lakes and streams; the other third was from groundwater. A total of 38 States (including the District of Columbia, which obtains its water from Maryland) relied on surface water for more than half their public supplies, whereas only 15 States obtained more than half their public water supplies from groundwater. California, Texas, New York, Illinois, and Pennsylvania each withdrew more than 1,000 Mgal/d of surface water for public supply in 2005, and 45 percent of the total surface-water withdrawals for public supply occurred in these five States. Three States—Florida, California, and Texas—each withdrew more than 1,000 Mgal/d of groundwater for public supply in 2005 and together accounted for 32 percent of total groundwater withdrawals for this category.
Trends in public-supply water withdrawals, 1950-2005
Estimated withdrawals for public supply increased continually since 1950 along with population served by public suppliers. Public-supply withdrawals more than tripled during this 50-year period and increased about 2 percent from 2000 to 2005. The percentage of population served by public suppliers increased from 62 percent for 1950 to 86 percent for 2005. Public-supply withdrawals represented about 8 percent of total withdrawals for 1950 and about 11 percent for 2005. If only fresh water is considered, public supply represented about 13 percent. The percentage of groundwater use for public supply increased from 26 percent for 1950 to 40 percent for 1985 and was about 33 percent in 2005.
Since the end of World War II there has been a trend of people moving out of the rural countryside and into the ever-expanding cities. This has important implications for our water resources. Communities have had to start building large water-supply systems to deliver water to new populations and industries.
In times past, when most people lived in rural areas, they had to find ways to supply their own water—often by drilling a well and pumping water to their homes. Not many city dwellers have a well in their backyards today. A public-water supply system, such as your local water department, nowadays delivers water to most homes. The bar chart below shows the trend toward urbanization over the last 50 years. Notice how the blue bars (representing the millions of people served by a public water-supply system) keeps going up while the green bars (representing the number of people who supply their own water) has trended downward, with 14 percent of the Nation's population supplying their own water in 2005.
Here is a bar chart showing the public-supplied and self-supplied populations in the U.S. from 1955-2005.
Data for freshwater withdrawals for 1980-2000 have been revised from original published values.
Public-supply water use, 2000
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