Understanding Public Water Supply in the U.S. Frequently asked questions
Overall in the U.S., there are about 53,000 public water systems that provide water service on a year-round basis, including about 41,000 groundwater systems and about 12,000 surface water systems. Since the largest systems tend to be the surface water systems, far more people in the U.S. are served by surface water than by groundwater.
Each water supply has its own characteristics, and individual treatment processes are selected with the specific source water in mind. Some common treatment processes include...
6. How is the quality of drinking water regulated in the U.S.?
All public water supplies must meet the detailed requirements set forth by the U.S. Environmental Protection Agency (USEPA). Numerous individual contaminants are regulated, falling within the categories of microorganisms, organic chemicals, inorganic chemicals, radionuclides, disinfectants, and disinfectant byproducts. In addition to the mandatory federal rules, each state may add supplemental requirements, if desired by that state. In most states, the USEPA authorizes a state-level agency (such as a department of natural resources or a department of environmental quality) to monitor all drinking water utilities in that state and to enforce the EPA rules.
9. How much water does a typical person use in the U.S.?
This depends on how we phrase the question. For example, in the U.S., the total use of publicly supplied drinking water per person averages about 157 gallons per person per day – this includes the water used in the residences, businesses, industries, government, institutions, and system leakage within an average city, divided by the population of the city. Note that this discussion does not include water withdrawn for agriculture, power generation, or other uses - those industries use even more water than the public water systems in many states.
Of the total 157 gallons per person per day, a typical resident uses about 50-70 gallons per person per day inside his/her home. Most of this indoor residential water is used for showers, bathing, toilet flushing, clothes washing, etc. - only a small portion is used for actual “drinking”. Water is also used for outdoor residential purposes, such as for lawns and plantings - outdoor uses can be particularly high in dry regions of the country.
The true value of water is a complex topic affected by many factors, including water shortages, supply/demand, technology, public infrastructure, and regulations. It is also interesting that commercially bottled water products are hundreds of times more expensive (on a per gallon basis) than publicly supplied water!