Drinking water quality

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Drinking water quality is a measure of how suitable water is for human consumption. Quality can be measured by examining a variety of factors, including the levels of chemicals and minerals in the water, the bacteria present, and temperature. All of these factors are affected by natural processes or human-made processes. Drinking water is treated in a variety of ways to remove contaminants and ensure water is safe to drink. Water quality standards include federally issued limits on these contaminants as well as guidelines used by localities at water treatment facilities.^[1][2]

This article includes information on drinking water sources, how drinking water is treated, drinking water standards, the issue of lead in drinking water, data on federal and state drinking water spending, and data on public water systems by state.

Background[edit]

Drinking water can come from surface water (water pumped from lakes, rivers, and reservoirs) or groundwater (water pumped from wells drilled into underground aquifers). Groundwater is located within cracks and spaces in sand, soil, and rocks below the Earth's surface. This water seeps into the ground and accumulates in rock beneath the Earth's surface. Sources of groundwater include rainfall, snowmelt, and water from the bottom of lakes and rivers. Surface waters include lakes, rivers, reservoirs, creeks, and streams. These waters are used for drinking, irrigation, electricity generation, and mining, and more.^[3][4][5]

A November 2014 report from the U.S. Geological Survey (USGS) found that the United States withdrew approximately 355 billion gallons of water per day in 2010. Of that total, 27.4 billion gallons per day were used for domestic water uses, including drinking, food preparation, dish and clothes washing, lawn and garden watering, maintaining pools and ponds, and more. The national average per capita usage was 88 gallons of water per day. Approximately 87 percent of domestic water use came from public supply deliveries; the remainder came from self-supplied withdrawals. Public supply deliveries include water withdrawn by public and private suppliers that deliver water to at least 25 people for several purposes, including drinking. Self-supplied withdrawals include water withdrawn directly from groundwater or surface water sources by the user. According to the USGS, public supply deliveries provided 268 million people in 2010—approximately 87 percent of the U.S. population that year—with domestic water.^[6][7]

The United States had approximately 153,000 publicly and privately owned water systems in 2015. These systems deliver water to 25 or more people regularly during the year.^[5][8]

Drinking water treatment[edit]

All sources of drinking water contain levels of naturally occurring contaminants. Water traveling over the surface or below ground can dissolve minerals and other particles and can absorb the various substances it touches. Naturally occurring contaminants can include bacteria, salts, and metals. Human-made contaminants can include pesticides, herbicides, and synthetic chemicals used in industrial processes. Water is treated to remove contaminants from both surface water and groundwater to ensure safety and quality. In general, surface water requires more treatment than groundwater as lakes, rivers, and streams contain more sediments than groundwater.^[9][10][11]

The following processes are used to remove particles, chemicals, microorganisms, and other potential contaminants from surface water and groundwater before the water is delivered for domestic use:^[12][13][14]

• The water is first treated by adding chemicals with a positive charge, which overcome negatively charged dirt and dissolved particles in the water. The particles and positively charged chemicals together form larger particles.
• These larger particles settle at the bottom of the water, a process known as sedimentation. With the larger particles settled at the bottom, the clearer water above is filtered through gravel, sand, charcoal, or other materials to remove additional dissolved particles, including bacteria, viruses, chemicals, parasites, and dust.
• After filtration, chlorine or another disinfectant is added to the water to eliminate remaining viruses or bacteria and to ensure quality as the water is delivered to homes and businesses.

Drinking water standards[edit]

Under the Safe Drinking Water Act of 1974, the Environmental Protection Agency (EPA) regulates how local public water systems remove contaminants from water before delivering it to local populations. Under the act, the EPA issues national drinking water standards to limit any contaminants that may pose health risks or are likely to be found in public water supplies. Federal standards apply to all privately and publicly owned water systems that regularly service at least 25 people. The EPA selects and regulates contaminants based on the following criteria:^{[15][16][17][18]}

• Potential adverse health effects
• A high likelihood that a contaminant will be found in public water systems at a level and frequency that could affect public health
• Probability that regulating a contaminant will reduce health risks for people who regularly use public water systems

Contaminants regulated through national drinking water standards include microorganisms (such as harmful bacteria), radionuclides (such as cancer-causing chemicals), organic chemicals (such as benzene and pesticides), and inorganic chemicals (such as arsenic and lead). The EPA sets maximum contaminant levels at which no known or anticipated adverse health effects occur in individuals. As of March 2017, national drinking water regulations applied to approximately 152,700 privately and publicly owned drinking water systems. Of that total, 51,350 water systems—approximately 34 percent of regulated systems—served the same residences year-round.^[15][18]

In addition, the act gave state governments primary enforcement and oversight authority over local public water systems (if the EPA determines a state has met the act's requirements). In addition, the 1996 amendments authorized $100 million per year in grants (between fiscal years 1997-2003) to states for administering the Public Water Supply Supervision (PWSS) Program, which is the main program established by the act for regulating public water systems.^[17]

Lead in drinking water[edit]

Elevated levels of lead can cause serious health problems for young children and older adults. The Safe Drinking Water Act included the following requirements on lead and drinking water supplies:^[15][17]

• The act restricted the amount of lead in pipes and plumbing equipment used to deliver drinking water. Specifically, the act (which was partially amended by the Reduction of Lead in Drinking Water Act of 2011) prohibited the use of pipes, pipe fittings, plumbing fittings, and fixtures that contain more than a weighted average of 0.25 percent lead. States have primary regulatory authority over this provision.
• In the 1986 amendments, Congress required public water system owners or operators to notify individuals who may be affected by lead in drinking water supplies caused by construction materials that were used to build the system or because the water was corrosive.
• In the 1996 amendments, Congress directed the EPA to issue standards limiting the amount of lead that may leach from new plumbing fittings or fixtures unless a voluntary industry standard was established within one year (an industry standard was established).

USA Today study (2016)[edit]

A 2016 report by the USA Today Network looked at EPA enforcement data and found that around 2,000 water systems nationwide (approximately 1.3 percent) had elevated levels of lead in tap water samples between 2012 and 2015. The report argued that three of every four water systems that had lead levels higher than 15 ppb served 500 people or fewer, while 70 systems with heightened levels of lead served at least 10,000 people.^[19]

The table below shows the data compiled by USA Today on the water samples with elevated lead levels by state. Texas and Pennsylvania had the most exceedances—183 and 157, respectively. Hawaii, Kentucky and South Dakota had the fewest lead level exceedances with one exceedance each. The full report can be found here, while the report's methodology can be found here.

Drinking water spending[edit]

According to the Congressional Budget Office, federal, state, and local government spending on water utilities—water supply and wastewater treatment facilities—totaled $108.9 billion in 2014. This was 26 percent of all federal, state, and local government spending on transportation and water infrastructure, which totaled $416 billion in 2014.^[20]

Approximately 96 percent of public spending on water utilities—$104.5 billion—came from state and local governments in 2014. Water utilities accounted for 33 percent of state and local government spending in 2014. According to the Congressional Budget Office, local governments are "almost exclusively responsible for spending on water utilities," according to the Congressional Budget Office.^[20]

The chart below shows federal spending on water utilities compared to state and local spending between 1965 and 2014. Since 1965, federal spending on water utilities peaked in 1977 at $16.8 billion and declined to $4.36 billion in 2014—a decrease of 74 percent. By contrast, state and local spending has grown since 1977, rising from $38.22 billion to $105.4 billion in 2014—an increase of 175 percent.^[20]

Public water systems by state[edit]

See also: Water systems in the United States

There were approximately 153,000 public water systems in the United States in 2015. The table below shows the number of public water systems (systems that supply drinking water to at least 25 people) in each state in 2015. Wisconsin had the most water systems at 11,641. Hawaii had the fewest water systems at 134.^[8]

Recent news[edit]

The link below is to the most recent stories in a Google news search for the terms Drinking water quality. These results are automatically generated from Google. Ballotpedia does not curate or endorse these articles.

See also[edit]

• 

  Environmental policy in the U.S.

• 

  Energy policy in the U.S.

• 

  Endangered species policy in the U.S.

Footnotes[edit]