Drinking water quality in the United States is generally safe. In 2016, over 90 percent of the nation's community water systems were in compliance with all published U.S. Environmental Protection Agency (US EPA) standards. Over 286 million Americans get their tap water from a community water system. Eight percent of the community water systems—large municipal water systems—provide water to 82 percent of the US population. The Safe Drinking Water Act requires the US EPA to set standards for drinking water quality in public water systems (entities that provide water for human consumption to at least 25 people for at least 60 days a year). Enforcement of the standards is mostly carried out by state health agencies. States may set standards that are more stringent than the federal standards.
Drinking water quality in the U.S. is regulated by state and federal laws and codes, which set maximum contaminant levels (MCLs) and Treatment Technique requirements for some pollutants and naturally occurring constituents, determine various operational requirements, require public notification for violation of standards, provide guidance to state primacy agencies, and require utilities to publish Consumer Confidence Reports.Joseph Cotruvo, Victor Kimm, Arden Calvert. "Drinking Water: A Half Century of Progress." EPA Alumni Association. March 1, 2016.
EPA has set standards for over 90 contaminants organized into six groups: microorganisms, disinfectants, disinfection byproducts, inorganic chemicals, organic chemicals and radionuclides. EPA also identifies and lists unregulated contaminants which may require regulation. The Contaminant Candidate List is published every five years, and EPA is required to decide whether to regulate at least five or more listed contaminants. There are also many chemicals and substances for which there are no regulatory standards applicable to drinking water utilities. EPA operates an ongoing research program to analyze various substances and consider whether additional standards are needed.
Most of the public water systems (PWS) that are out of compliance are small systems in rural areas and small towns. For example, in 2015, 9% of water systems (21 million people) were reported as having water quality violations and therefore were at risk of drinking contaminated water that did not meet water quality standards.
Background In early US history, drinking water quality in the country was managed by individual drinking water utilities and at the state and local level. In 1914 the U.S. Public Health Service (PHS) published a set of drinking water standards, pursuant to existing federal authority to regulate interstate commerce, and in response to the 1893 Interstate Quarantine Act.United States. "An act granting additional quarantine powers and imposing additional duties upon the Marine-Hospital Service." (Commonly known as the "Interstate Quarantine Act of 1893.") 52nd Congress, 2nd session, Chapter 114. February 15, 1893. As such the standards were directly applicable only to interstate common carriers such as railroads. For local drinking water utilities, these standards were basically recommendations and not enforceable requirements. However, many municipal utilities began to voluntarily adopt the standards.
Ultimately the PHS standards were adopted and expanded as national drinking water standards after passage of the 1974 Safe Drinking Water Act (SDWA), and U.S. water quality became subject to a whole new generation of federal standards.EPA Alumni Association: Senior EPA officials discuss early implementation of the Safe Drinking Water Act of 1974, Video, Transcript. (see p. 3)
Enforcement of standards
The SDWA requires EPA to issue federal regulations for public water systems.United States. Safe Drinking Water Act. ; ; et seq. December 16, 1974. There are no federal regulations covering private drinking water wells, although some state and local governments have issued rules for these wells. EPA enters into primary enforcement authority (primacy) agreements with state governments, so in most states EPA does not directly enforce the SDWA. State rules can be different from EPA's, but they must be at least as stringent.
EPA defines a public water system (PWS) as an entity that provides water for human consumption to at least 25 people (or at least 15 connections) for at least 60 days a year. There are three types of public water system: community systems (like cities or trailer parks); non-transient, non-community systems (like factories or schools with their own water source); and transient non-community systems (like rural restaurants or camps).
Enforcement of drinking water standards in small water systems is less consistent than enforcement in large systems. As of 2016 more than 3/4ths of small community water systems that were classified as having serious health violations by EPA still had the same violations three years later. Some violations included an overabundance of lead, exceeding allowed rates for nitrate and fecal coliform. Around half of the most contaminated water systems were located in Kansas, Texas and Puerto Rico. EPA's Office of Enforcement and Compliance Assurance noted that the agency faced "a daunting list of challenges" in its continuing efforts, particularly with small systems that "lack the basic infrastructure, resources and capacity to provide clean drinking water."
Consumer Confidence Reports EPA's Consumer Confidence Rule of 1998 requires community public water suppliers to provide customers with annual reports of drinking water quality, called Consumer Confidence Reports (CCR). Each year by July 1 anyone connected to a public water system should receive in the mail an annual water quality report that tells where your water comes from and what's in it. Consumers can find out about these local reports on a map provided by EPA.
The regulation requires water suppliers to list the water sources, report detected contaminants and the system's compliance with National Primary Drinking Water Regulations in the annual reports. Suppliers may also provide additional information such as explanation of the system's treatment processes, advice on water conservation and information about protecting the community's water sources.
The US Environmental Protection Agency (EPA) regulates the allowable levels of some contaminants in public water systems. There may also be numerous contaminants in tap water that are not regulated by EPA and yet potentially harmful to human health. Community water systems—those systems that serve the same people throughout the year—must provide an annual "Consumer Confidence Report" to customers. The report identifies contaminants, if any, in the water system and explains the potential health impacts.
Several studies show that a Safe Drinking Water Act (SDWA) health violation occurs in around 7-8% of community water system (CWS) in an average year. Around 16 million cases of acute gastroenteritis occur each year in the US, due to the existence of contaminants in drinking water.
Common drinking water contaminants Studies have shown that there can be more than 80 common contaminants in treated drinking water that may pose a risk to human health. These contaminants fall into two separate categories, acute and chronic effects. Acute effects occur within hours or days of the time that a person consumes a contaminant. People can experience acute health effects from almost any contaminant if they are exposed to extraordinarily high levels (as in the case of a spill). In drinking water, microbes, such as bacteria and viruses, are the contaminants with the greatest chance of reaching levels high enough to cause acute health effects. Acute effects contaminants are the most commons type that are found in drinking water. Acute contaminants are usually easy for the human body to fight off and don't normally have long lasting health effects. Chronic effects occur after people consume a contaminant at levels over EPA's safety standards over the course of many years. The drinking water contaminants that can have chronic effects include chemicals (such as disinfection byproducts, solvents and pesticides), radionuclides (such as radium), and minerals (such as arsenic). Examples of these chronic effects include cancer, liver or kidney problems, or reproductive difficulties.
Though these chronic contaminants are rare in the US, there are many parts of the world that battle with these chronic contaminants and have to face the possible hazards on a daily basis. A few common water-borne contaminants include aluminum, ammonia, arsenic, barium, cadmium, chloramine, chromium, copper, fluoride, bacteria and viruses, lead, nitrates and nitrites, mercury, perchlorate, radium, selenium, silver, and uranium. Some of these contaminants are easy to detect through human senses, such as smell and taste, and other contaminants are impossible to detect with the human eye. Some of the most dangerous contaminants are consumed without any notice. It is extremely important to know the difference between chemical and biological contaminants. Chemical contaminants are elements or compounds that can either be naturally occurring or man-made. These contaminants usually result in external/internal damages to the body. Biological contaminants are organisms that are found in water these contaminates include viruses and bacteria and are usually fought off by the bodies immune system.
Substances for which there are federal standards
EPA has promulgated over 90 standards for microorganisms, chemicals and radionuclides. The standards are organized into six groups: Microorganisms Disinfectants Disinfection byproducts Inorganic chemicals Organic chemicals Radionuclides.
Microorganisms EPA has issued standards for Cryptosporidium, Giardia lamblia, Legionella, coliform bacteria and enteric viruses. EPA also requires two microorganism-related tests to indicate water quality: plate count and turbidity.
Cryptosporidium Cryptosporidium is a parasite that has a thick outer shell and thus is highly resistant to disinfection with chlorine. It gets into rivers and lakes from the stools of infected animals. Municipal water treatment plants usually remove Cryptosporidium oocysts through filtration. Nevertheless, at least five outbreaks of cryptosporidiosis in the U.S. have been associated with contaminated drinking water, including a well-publicized one in Milwaukee, Wisconsin in 1993.
The Long Term 2 Enhanced Surface Water Treatment Rule ("LT2 rule") of 2006 requires evaluation of surface water treatment plants and that these plants take specific actions to minimize the potential for Cryptosporidium infections.
Disinfectants