Drinking water quality in the United States
Drinking water quality in the United States is generally good. In 2016, over 90 percent of the nation's community water systems were in compliance with all more-than-90 U.S. Environmental Protection Agency (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.
Most of the systems that are out of compliance are small systems in rural areas and small towns, partly because most public water systems are small ones. Drinking water quality in the U.S. is regulated by state and federal laws and codes, which set Maximum Contaminant Levels (MCLs) 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.
Historically, up through 1914, drinking water quality in the country was managed at the state and local level. After that, interstate waters were protected using United States Public Health Service (USPHS) standards. Ultimately the USPHS 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.
Enforcement of standardsEdit
The SDWA requires EPA to issue federal regulations for public water systems. There are no federal regulations covering private drinking water wells, although some state and local governments have issued rules for these wells. The EPA enters into primary enforcement authority (primacy) agreements with state governments, so in most states the EPA does not directly enforce the SDWA. State rules can be different from the EPA's, but they must be at least as stringent.
The 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. According to a 2016 USA Today article, more than 3/4ths of small community water systems that were classified as having serious health violations by the 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. In a letter, the 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 ReportsEdit
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. Elizabeth Royte wrote in 2008 that the reported contaminant numbers are annual averages and that utilities may not provide data on unregulated contaminants.:223 During 2011-2012 EPA conducted a review of the CCR process which including public hearings. EPA agreed with recommendations from commenters that water utilities and regulatory agencies should make improvements to the reports in order to make them more understandable to the public. The Agency planned to accomplish this by providing additional guidance and training to the utilities, and stated that no revisions to the CCR regulation were needed.
Common Drinking Water ContaminatesEdit
When it comes to drinking water studies have shown that there are more than 80 common contaminants that may pose a risk to human health. These contaminates 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 suffer 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 are the most commons contaminates found in drinking water, acute contaminates 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.
Figure 2 shows several water contaminates that are mostly found in drinking water. These contaminates do not only effect human health but agriculture production as well, causing possible cross contaminating. 
Though these Chronic contaminates are rare to come across in the US, there are many parts of the world that battle with these chronic contaminates and have to face the possible hazards on a daily basis. A few common water borne contaminates include Aluminum, Ammonia Arsenic, Barium, Cadmium, Chloramine, Chromium, Copper, Fluoride, Bacteria & Viruses, Lead, Nitrates/Nitrites, Mercury, Perchlorate, Radium, Selenium, Silver, and Uranium. Some of these contaminates are easy to detect through human senses, such as smell and taste, and other contaminates are impossible to detect with the human eye. Some of the most dangerous contaminates are consumed without any notice. It is extremely important to know the difference between chemical and biological contaminates, chemical contaminates are elements or compounds that can either be naturally occurring or man-made. These contaminates usually result in external/internal damages to the body. Biological contaminates 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 standardsEdit
Federal drinking water standards are organized into six groups:
- Disinfection byproducts
- Inorganic chemicals
- Organic chemicals
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 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 specific treatments be provided in order to minimize the potential for Cryptosporidium infections from public water at supplies using surface water.
Disinfectants such as chlorine can react with natural material in the water to form disinfection byproducts such as trihalomethanes. Animal studies indicate that none of the chlorination byproducts studied to date is a potent carcinogen at concentrations normally found in drinking water. According to the "GreenFacts" website, there is insufficient epidemiological evidence to conclude that drinking chlorinated water causes cancers. The results of currently published studies do not provide convincing evidence that chlorinated water causes adverse pregnancy outcomes.
Most people associate fluoride with the practice of intentionally adding fluoride to public drinking-water supplies for the prevention of tooth decay. However, fluoride can also enter public water systems from natural sources, including runoff from weathering of fluoride-containing rocks and soils and leaching from soil into groundwater. Fluoride pollution from various industrial emissions can also contaminate water supplies. In a few areas of the United States, fluoride concentrations in water are much higher than normal, mostly from natural sources. In 1986, EPA established a maximum allowable concentration for fluoride in drinking water of 4 milligrams per liter (mg/L). After reviewing research on various health effects from exposure to fluoride, the Committee on Fluoride in Drinking Water of the National Research Council concluded in 2006 that EPA's drinking water standard for fluoride does not protect against adverse health effects. Just over 200,000 Americans live in communities where fluoride levels in drinking water are 4 mg/L or higher. Children in those communities are at risk of developing severe tooth enamel fluorosis, a condition that can cause tooth enamel loss and pitting. It can also increase the risk of bone fractures. The report concluded unanimously that the present maximum contaminant level goal of 4 mg/L for fluoride should be lowered.
Several states have more stringent regulations.
Lead typically gets into drinking water after the water leaves the treatment plant. The source of lead is most likely pipe or solder in older service connections or older plumbing inside homes, from which lead "leaks" into the water through corrosion. EPA's lead and copper rule, last revised in 2007, defines an "action level" of 15 parts per billion (ppb) for lead, which is different from a Maximum Contaminant Level.
If tests show that the level of lead in drinking water is in the area of 15 ppb or higher, it is advisable – especially if there are young children in the home – to replace old pipes, to filter water, or to use bottled water. EPA estimates that more than 40 million U.S. residents use water "that can contain lead in excess of 15 ppb". In Washington, DC these concerns have led to a $408 million program carried out since 2004 to replace lead service connections to about 35,000 homes. The effectiveness of the program has, however, been put in question in 2008 by WASA, the city's utility. In 2016, more than 5,000 drinking water systems were found to be in violation of the lead and copper rule.
Impacts of arsenicEdit
When it comes to water quality it is important to know what chemicals can possibly be lurking in ones drinking water and the long term affects those contaminates can have on one’s health. As seen in 1879, arsenic was the first of several chemicals that have been recognized to cause cancer as a long term affect. A few years after testing for levels of arsenic in drinking water high rates of both skin and lung cancers arose. Startling results from Taiwan, appearing in 1985, showed increased mortality from several cancers, especially lung, bladder, and kidney cancers (13). Bladder cancer mortality rates for those with more than 600 µg/liter of arsenic in their water were more than 30 to 60 times the rates in the unexposed population. With these high rates of cancers being found, people were starting to witness a large shift of human diets, cancer rates begin to link with available drinking water and agricultural efforts. To this day the communities of Taiwan still face high levels of arsenic in their water, this is an ongoing problem that has been going on for years. In this case arsenic is only one of the many dangerous contaminates that can be present in water, Figure 1 shows the short term effects resulting from the exposure to Arsenic. The characteristic skin lesions included pigmentation changes, mainly on the upper chest, arms and legs, and keratoses of the palms of the hands and soles of the feet (Fig. 1). After ruling out other causes, water sources used by the patients were analysed, and the diagnosis of arsenic-caused disease was confirmed. Over time this expose to arsenic became for extreme, long term exposure resulted in cancerous effects all over the body.
Substances for which there are no federal standardsEdit
EPA maintains the Contaminant Candidate List (CCL), a list of substances which are being considered for possible regulation in the drinking water program. In an effort to assess the importance of certain substances as contaminants, the National Primary Drinking Water Regulations have required some public water systems to monitor for some of those substances.
Perfluorooctanoic acid (PFOA) is a synthetic perfluorinated carboxylic acid and fluorosurfactant. It has been used in the manufacture of such prominent consumer goods as polytetrafluoroethylene (PTFE; Teflon and similar products). PFOA has been manufactured since the 1940s in industrial quantities. PFOA persists indefinitely in the environment. It is a toxicant and carcinogen in animals. PFOA has been detected in the blood of more than 98% of the general US population in the low and sub-parts per billion (ppb) range, and levels are higher in chemical plant employees and surrounding subpopulations.
In the United States there are no federal drinking water standards for PFOA, PFOS or PFNA (collectively referred to as perfluorinated alkylated substances or PFAS) as of late 2018. EPA began requiring public water systems to monitor for PFOA and PFOS in 2012, and published drinking water health advisories, which are non-regulatory technical documents, in 2016. EPA has not announced whether it will develop a National Primary Drinking Water Regulation for these contaminants.
In November 2017 the New Jersey Department of Environmental Protection announced plans to develop its own drinking water standards for PFOA. New Jersey published a standard for PFNA in September 2018, the first state to do so. The state set the MCL at 13 parts per trillion (ppt). Other states that have issued PFAS standards include Michigan, New York and Vermont.
Methyl tert-butyl ether (MTBE) is used as a gasoline additive, as well as in various industrial manufacturing processes. The compound has contaminated groundwater and soil across the U.S., and its use has been banned in some states, including California and New York. (See MTBE controversy.) EPA included MTBE on its first Contaminant Candidate List, published in 1998, but has not announced whether it will develop a regulation.
Perchlorate has been detected in public drinking water supplies of over 11 million people in 22 states at concentrations of at least 4 parts per billion (ppb). Above a certain concentration perchlorate alters the production of thyroid hormones by the body, chemicals that are essential for proper development of the fetus and for normal metabolic functioning of the body. According to patient advocate and writer Mary Shomon, people with thyroid conditions, as well as pregnant women and their fetuses are particularly at risk. However, according to the Perchlorate Information Bureau, an industry-supported group, sound scientific and medical research shows that the low levels of perchlorate being detected in drinking water are not dangerous to human health. Still according to the same source, these studies on adults, newborns and children provide reason to believe that low levels of perchlorate (even at levels many times higher than the minute amounts being found in some drinking water supplies) also have no measurable effect on pregnant women or fetuses.
One source of perchlorate in drinking water is the past production of solid rocket propellants using perchlorate, combined with poor disposal practices. Industrial accidents and agricultural fertilizers are also suspected as sources of contamination of drinking water by perchlorate. Perchlorate is also found in breast milk at significant levels, possibly attributable to perchlorate in drinking water and foods. The challenge of defining an acceptable level of perchlorate in drinking water sets two opposing groups with significantly different views against each other. In a draft risk assessment made in 2002, EPA suggested that levels higher than 1 part per billion (ppb) pose a health risk. In contrast, the Defense Department contended that perchlorate at 200 ppb has no lasting effect on humans. Perchlorate is one of only four of the seventy chemicals for which EPA has set public health goals that have a safety factor of 10, rather than the usual safety factors of 100 or 1000.:21 In 2004 eight states had non-binding advisories for perchlorate in drinking water, ranging from 1 to 18 ppb. Only two states—Massachusetts and California—set legally binding maximum contaminant levels on the allowable amount of perchlorate in drinking water, at 2 ppb and 6 ppb respectively.
EPA issued an "Interim Health Advisory" for perchlorate in 2009, while it continued to evaluate whether to issue regulatory standards. In 2011 the agency announced that it would develop regulations for perchlorate. In 2016 a federal district court in New York issued a consent decree that initially required EPA to issue a proposed rule in October 2018, and a final rule in December 2019. The modified court order requires EPA to issue a proposed rule by May 28, 2019.
Many pharmaceutical substances are not regulated under the Safe Drinking Water Act. They have been found in tiny concentrations in the drinking water of several US cities affecting at least 41 million Americans, according to a five-month inquiry by the Associated Press published in March 2008. Pharmaceutical substances are used worldwide and are a big part of some peoples lives. These substances not being regulated under the Safe Drinking Water Act has potential to have major impact on the lives of many individuals. At any point a region can face strong pollution and the pharmaceuticals made in that area can have a large chance of being contaminated as well causing possible harm to the consumers. According to the AP report, researchers do not yet understand the exact risks from decades of persistent exposure to random combinations of low levels of pharmaceuticals.
Pharmaceuticals are included in a broader group of substances currently being studied by EPA, "Pharmaceuticals and Personal Care Products (PPCPs)." This group includes classes of common consumer products such as cosmetics, fragrances, vitamins and sunscreen products. These cosmetics listed have the potential to pose health risks to its consumers strictly due to the lack of regulations of clean water use. This can cause many problems, those who receive water borne illnesses from these cosmetics may scapegoat the illness to their water sources. the Safe Drinking Water Act is put in place in attempt to protect public health. Water contaminates are some of the harshest contaminates out here. When sources such as pharmaceuticals don't require this protection it is important to monitor these contaminates. Monitoring can occur though taking part in testing ones water and pharmaceuticals though monitoring under the Disinfection Byproduct rule. This rule if approved by the State, residual disinfectant concentrations for chlorine, chlorinates, and chlorine dioxide may be measured using DPD colormetric test kits.  This method has the potential to limit these harmful contaminates from both water and pharmaceutical use. Without disinfection methods as shown here, there would be little to no alternatives when it comes to finding a safe and effective way to be sure the products being used are safe. Due to all the regulations put at hand individuals should feel safe using water products, as these products are used in everyone's daily life.
EPA proposed regulations for radon in 1991 and 1999. In 2010 it was reported that EPA had not finalized the proposal due to concerns raised by some utilities about high costs for controlling radon. However, nine states had issued their own radon guidelines.
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