Drinking water, also known as potable water, is water that is safe to drink or to use for food preparation. The amount of drinking water required varies. It depends on physical activity, age, health issues, and environmental conditions. Americans, on average, drink one litre of water a day and 95% drink less than three litres per day. For those who work in a hot climate, up to 16 litres a day may be required. Water is essential for life.
Typically in developed countries, tap water meets drinking water quality standards, even though only a small proportion is actually consumed or used in food preparation. Other typical uses include washing, toilets, and irrigation. Greywater may also be used for toilets or irrigation. Its use for irrigation however may be associated with risks. Water may also be unacceptable due to levels of toxins or suspended solids.
Globally, by 2015, 89% of people had access to water from a source that is suitable for drinking – called improved water source. In Sub-Saharan Africa, access to potable water ranged from 40% to 80% of the population. Nearly 4.2 billion people worldwide had access to tap water, while another 2.4 billion had access to wells or public taps. The World Health Organization considers access to safe drinking-water a basic human right.
About 1 to 2 billion people lack safe drinking water, a problem that causes 30,000 deaths each week. More people die from unsafe water than from war, U.N. Secretary-General Ban Ki-Moon said in 2010.
According to the World Health Organization's 2017 report, safe drinking-water is water that "does not represent any significant risk to health over a lifetime of consumption, including different sensitivities that may occur between life stages".:2
A 'safely managed drinking water service" is "one located on premises, available when needed and free from contamination". By 2015, 5.2 billion people representing 71% of the global population used safely managed drinking water service.
The terms 'improved water source' and 'unimproved water source' were coined in 2002 as a drinking water monitoring tool by the JMP of UNICEF and WHO. The term, improved water source refers to "piped water on premises (piped household water connection located inside the user’s dwelling, plot or yard), and other improved drinking water sources (public taps or standpipes, tube wells or boreholes, protected dug wells, protected springs, and rainwater collection)". Improved sources are also monitored based on whether water is available when needed (5.8 billion people), located on premises (5.4 billion), free from contamination (5.4 ), and "within 30 minutes' round trip to collect water.':3 While improved water sources such as protected piped water are more likely to provide safe and adequate water as they may prevent contact with human excreta, for example, this is not always the case. According to a 2014 study, approximately 25% of improved sources contained fecal contamination.
The SDC basic drinking water service is one in which a "round trip to collect water takes 30 minutes or less". Only Australia, New Zealand, North America and Europe have almost achieved universal basic drinking water services.:3
According to the World Health Organization, "access to safe drinking-water is essential to health, a basic human right and a component of effective policy for health protection.":2
The amount of drinking water required is variable. It depends on physical activity, age, health, and environmental conditions. In a temperate climate under normal conditions, adequate water intake is about 2.7 litres (95 imp fl oz; 91 US fl oz) for adult women and 3.7 litres (130 imp fl oz; 130 US fl oz) for adult men. Physical exercise and heat exposure cause loss of water and therefore may induce thirst and greater water intake. Physically active individuals in hot climates may have total daily water needs of 6 litres (210 imp fl oz; 200 US fl oz) or more. The European Food Safety Authority recommends 2.0 litres (70 imp fl oz; 68 US fl oz) per day for adult women and 2.5 litres (88 imp fl oz; 85 US fl oz) per day for adult men.
In the United States, the reference daily intake (RDI) for total water is 3.7 litres (130 imp fl oz; 130 US fl oz) per day for human males older than 18, and 2.7 litres (0.59 imp gal; 0.71 US gal) per day for human females older than 18 which includes drinking water, water in beverages, and water contained in food. An individual's thirst provides a better guide for how much water they require rather than a specific, fixed quantity. Americans, on average, drink one litre (35 imp fl oz; 34 US fl oz) of water a day and 95% drink less than three litres (110 imp fl oz; 100 US fl oz) per day.
The drinking water contribution to mineral nutrients intake is also unclear. Inorganic minerals generally enter surface water and ground water via storm water runoff or through the Earth's crust. Treatment processes also lead to the presence of some minerals. Examples include calcium, zinc, manganese, phosphate, fluoride and sodium compounds. Water generated from the biochemical metabolism of nutrients provides a significant proportion of the daily water requirements for some arthropods and desert animals, but provides only a small fraction of a human's necessary intake. There are a variety of trace elements present in virtually all potable water, some of which play a role in metabolism. For example, sodium, potassium and chloride are common chemicals found in small quantities in most waters, and these elements play a role in body metabolism. Other elements such as fluoride, while beneficial in low concentrations, can cause dental problems and other issues when present at high levels.
Fluid balance is key. Profuse sweating can increase the need for electrolyte (salt) replacement. Water intoxication (which results in hyponatremia), the process of consuming too much water too quickly, can be fatal.
Water covers some 70% of the Earth's surface. Approximately 97.2% of it is saline, just 2.8% fresh. Potable water is available in almost all populated areas of the Earth, although it may be expensive and the supply may not always be sustainable. Sources where water may be obtained include:
Springs are often used as sources for bottled waters. Tap water, delivered by domestic water systems refers to water piped to homes and delivered to a tap or spigot. For these water sources to be consumed safely, they must receive adequate treatment and meet drinking water regulations.
The most efficient way to transport and deliver potable water is through pipes. Plumbing can require significant capital investment. Some systems suffer high operating costs. The cost to replace the deteriorating water and sanitation infrastructure of industrialized countries may be as high as $200 billion a year. Leakage of untreated and treated water from pipes reduces access to water. Leakage rates of 50% are not uncommon in urban systems.
Because of the high initial investments, many less wealthy nations cannot afford to develop or sustain appropriate infrastructure, and as a consequence people in these areas may spend a correspondingly higher fraction of their income on water. 2003 statistics from El Salvador, for example, indicate that the poorest 20% of households spend more than 10% of their total income on water. In the United Kingdom authorities define spending of more than 3% of one's income on water as a hardship.
In the US, the typical water consumption per capita, at home, is 69.3 US gallons (262 l; 57.7 imp gal) of water per day. Of this, only 1% of the water provided by public water suppliers is for drinking and cooking. Uses include (in decreasing order) toilets, washing machines, showers, baths, faucets, and leaks. Any public water system, which is defined as a system that serves more than 25 customers or 15 service connections, is regulated by the U.S. Environmental Protection Agency under the Safe Water Drinking Act based on minimum contaminant levels the agency sets. In some parts of the country water supplies are dangerously low due to drought and depletion of the aquifers, particularly in the West and the South East region of the U.S.
The drinking water in Canada's cities is regularly tested and considered safe, but on many native reserves clean drinking water is considered a luxury. The latest Canadian government of 2015 was to spend additional funds to fix the problem but has not had success.
In 1990, only 76 percent of the global population had access to drinking water. By 2015 that number had increased to 91 percent. 89% of people having access to water from a source that is suitable for drinking – called "improved water source". In 1990, most countries in Latin America, East and South Asia, and Sub-Saharan Africa were well below 90%. In Sub-Saharan Africa, where the rates are lowest, household access ranges from 40 to 80 percent.
Estimates suggest that at least 25% of improved sources contain fecal contamination. 1.8 billion people still use an unsafe drinking water source which may be contaminated by feces. This can result in infectious diseases, such as gastroenteritis, cholera, and typhoid, among others. Reduction of waterborne diseases and development of safe water resources is a major public health goal in developing countries. Bottled water is sold for public consumption in most parts of the world.
One of the Millennium Development Goals (MDGs) set by the UN includes environmental sustainability. In 2004, only 42% of people in rural areas had access to clean water worldwide. Projects such as Democratisation of Water and Sanitation Governance by Means of Socio-Technical Innovations work to develop new accessible water treatment systems for poor rural areas, reducing the price of drinking water from US $6.5 per cubic meter to US $1.
The World Health Organization/UNICEF Joint Monitoring Program (JMP) for Water Supply and Sanitation  is the official United Nations mechanism tasked with monitoring progress towards the Millennium Development Goal (MDG) relating to drinking-water and sanitation (MDG 7, Target 7c), which is to: "Halve, by 2015, the proportion of people without sustainable access to safe drinking-water and basic sanitation".
According to this indicator on improved water sources, the MDG was met in 2010, five years ahead of schedule. Over 2 billion more people used improved drinking water sources in 2010 than did in 1990. However, the job is far from finished. 780 million people are still without improved sources of drinking water, and many more people still lack safe drinking water. Estimates suggest that at least 25% of improved sources contain fecal contamination and an estimated 1.8 billion people globally use a source of drinking water which suffers from fecal contamination. The quality of these sources varies over time and often gets worse during the wet season. Continued efforts are needed to reduce urban-rural disparities and inequities associated with poverty; to dramatically increase safe drinking water coverage in countries in sub-Saharan Africa and Oceania; to promote global monitoring of drinking water quality; and to look beyond the MDG target towards universal coverage.
One organisation working to improve the availability of safe drinking water in some the world's poorest countries is WaterAid International. Operating in 26 countries, WaterAid is working to make lasting improvements to peoples' quality of life by providing long-term sustainable access to clean water in countries such as Nepal, Tanzania, Ghana and India. It also works to educate people about sanitation and hygiene.
Sanitation and Water for All (SWA) is a partnership that brings together national governments, donors, UN agencies, NGOs and other development partners. They work to improve sustainable access to sanitation and water supply to meet and go beyond the MDG target. In 2014, 77 countries had already met the MDG sanitation target, 29 were on track and, 79 were not on-track.
The World Wildlife Fund predicts that in the Himalayas, retreating glaciers could reduce summer water flows by up to two-thirds. In the Ganges area, this would cause a water shortage for 500 million people. The head of China's national development agency in 2007 said 1/4th the length of China's seven main rivers were so poisoned the water harmed the skin. United Nations secretary-general Ban Ki-moon has said this may lead to violent conflicts. ref>Richard Wachman (8 December 2007). "Water becomes the new oil as world runs dry". The Guardian. Archived from the original on 25 September 2015.
Contaminated water is estimated to result in more than half a million deaths per year. Contaminated water together with lack of sanitation was estimated to cause about one percent of disability adjusted life years worldwide in 2010.
Over 90% of deaths from diarrheal diseases in the developing world today occur in children under five years old.:11 Malnutrition, especially protein-energy malnutrition, can decrease the children's resistance to infections, including water-related diarrheal diseases. Between 2000 and 2003, 769,000 children under five years old in sub-Saharan Africa died each year from diarrheal diseases. Only thirty-six percent of the population in the sub-Saharan region have access to proper means of sanitation. More than 2,000 children's lives are lost every day. In South Asia, 683,000 children under five years old died each year from diarrheal disease from 2000 to 2003. During the same period, in developed countries, 700 children under five years old died from diarrheal disease. Improved water supply reduces diarrhea morbidity by 25% and improvements in drinking water through proper storage in the home and chlorination reduces diarrhea episodes by 39%.
Some efforts at increasing the availability of safe drinking water have been disastrous. When the 1980s were declared the "International Decade of Water" by the United Nations, the assumption was made that groundwater is inherently safer than water from rivers, ponds, and canals. While instances of cholera, typhoid and diarrhea were reduced, other problems emerged due to polluted groundwater.
Sixty million people are estimated to have been poisoned by well water contaminated by excessive fluoride, which dissolved from granite rocks. The effects are particularly evident in the bone deformations of children. Similar or larger problems are anticipated in other countries including China, Uzbekistan, and Ethiopia. Although helpful for dental health in low dosage, fluoride in large amounts interferes with bone formation.
Half of Bangladesh's 12 million tube wells contain unacceptable levels of arsenic due to the wells not dug deep enough (past 100 metres). The Bangladeshi government had spent less than US$7 million of the 34 million allocated for solving the problem by the World Bank in 1998. Natural arsenic poisoning is a global threat with 140 million people affected in 70 countries globally. These examples illustrate the need to examine each location on a case by case basis and not assume what works in one area will work in another.
In 2008, the Swiss Federal Institute of Aquatic Science and Technology, Eawag, developed a method by which hazard maps could be produced for geogenic toxic substances in groundwater. This provides an efficient way of determining which wells should be tested.
Parameters for drinking water quality typically fall within three categories:
Chemical parameters tend to pose more of a chronic health risk through buildup of heavy metals although some components like nitrates/nitrites and arsenic can have a more immediate impact. Physical parameters affect the aesthetics and taste of the drinking water and may complicate the removal of microbial pathogens.
Originally, fecal contamination was determined with the presence of coliform bacteria, a convenient marker for a class of harmful fecal pathogens. The presence of fecal coliforms (like E. Coli) serves as an indication of contamination by sewage. Additional contaminants include protozoan oocysts such as Cryptosporidium sp., Giardia lamblia, Legionella, and viruses (enteric). Microbial pathogenic parameters are typically of greatest concern because of their immediate health risk.
Throughout most of the world, the most common contamination of raw water sources is from human sewage in particular human faecal pathogens and parasites. In 2006, waterborne diseases were estimated to cause 1.8 million deaths while about 1.1 billion people lacked proper drinking water. In parts of the world, the only sources of water are from small streams that are often directly contaminated by sewage.
There is increasing concern over the health effects of engineered nanoparticles (ENPs) released into the natural environment. One potential indirect exposure route is through the consumption of contaminated drinking waters. To address these concerns, the U.K. Drinking Water Inspectorate (DWI) has published a "Review of the risks posed to drinking water by man-made nanoparticles" (DWI 70/2/246). The study, which was funded by the Department for Food and Rural Affairs (Defra), was undertaken by the Food and Environment Research Agency (Fera) in collaboration with a multi-disciplinary team of experts including scientists from the Institute of Occupational Medicine/SAFENANO. The study explored the potential for ENPs to contaminate drinking water supplies and to establish the significance of the drinking water exposure route compared to other routes of exposure.
Access to safe drinking water is indicated by safe water sources. These improved drinking water sources include household connection, public standpipe, borehole condition, protected dug well, protected spring, and rain water collection. Sources that do not encourage improved drinking water to the same extent as previously mentioned include: unprotected wells, unprotected springs, rivers or ponds, vender-provided water, bottled water (consequential of limitations in quantity, not quality of water), and tanker truck water. Access to sanitary water comes hand in hand with access to improved sanitation facilities for excreta, such as connection to public sewer, connection to septic system, or a pit latrine with a slab or water seal.
Most water requires some treatment before use; even water from deep wells or springs. The extent of treatment depends on the source of the water. Appropriate technology options in water treatment include both community-scale and household-scale point-of-use (POU) designs. Only a few a large urban areas such as Christchurch, New Zealand have access to sufficiently pure water of sufficient volume that no treatment of the raw water is required.
In emergency situations when conventional treatment systems have been compromised, waterborne pathogens may be killed or inactivated by boiling but this requires abundant sources of fuel, and can be very onerous on consumers, especially where it is difficult to store boiled water in sterile conditions. Other techniques, such as filtration, chemical disinfection, and exposure to ultraviolet radiation (including solar UV) have been demonstrated in an array of randomized control trials to significantly reduce levels of water-borne disease among users in low-income countries, but these suffer from the same problems as boiling methods.
Another type of water treatment is called desalination and is used mainly in dry areas with access to large bodies of saltwater.
The ability of point of use (POU) options to reduce disease is a function of both their ability to remove microbial pathogens if properly applied and such social factors as ease of use and cultural appropriateness. Technologies may generate more (or less) health benefit than their lab-based microbial removal performance would suggest.
The current priority of the proponents of POU treatment is to reach large numbers of low-income households on a sustainable basis. Few POU measures have reached significant scale thus far, but efforts to promote and commercially distribute these products to the world's poor have only been under way for a few years.
Solar water disinfection is a low-cost method of purifying water that can often be implemented with locally available materials. Unlike methods that rely on firewood, it has low impact on the environment.
The EU sets legislation on water quality. Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy, known as the water framework directive, is the primary piece of legislation governing water. This drinking water directive relates specifically to water intended for human consumption.
Each member state is responsible for establishing the required policing measures to ensure that the legislation is implemented. For example, in the UK the Water Quality Regulations prescribe maximum values for substances that affect wholesomeness and the Drinking Water Inspectorate polices the water companies.
In the United States, the Environmental Protection Agency (EPA) sets standards for tap and public water systems under the Safe Drinking Water Act (SDWA). As of 2016, it had minimum contaminant levels for 88 organic and inorganic chemicals. The Food and Drug Administration (FDA) regulates bottled water as a food product under the Federal Food, Drug, and Cosmetic Act (FFDCA). Bottled water is not necessarily purer pure, or more tested, than public tap water. Peter W. Preuss, former head of EPA's division analyzing environmental risks, has been "particularly concerned" about current drinking water standards, and suggested in 2009 that regulations against certain chemicals should be tightened.
In 2010 the EPA showed that 54 active pharmaceutical ingredients and ten metabolites had been found in treated drinking water. An earlier study from 2005 by the EPA and the Geographical Survey states that 40% of water was contaminated with nonprescription pharmaceuticals, and it has been reported that 8 of the 12 most commonly occurring chemicals in drinking water are estrogenic hormones. Of the pharmaceutical components found in drinking water, the EPA only regulates lindane. In 2009, the EPA did announce another 13 chemicals, hormones, and antibiotics that could potentially be regulated. In 2011 EPA announced it would develop regulations for perchlorate.
A list of normative documents that regulate the quality of drinking water in Russia:
The qualitative and quantitative aspects of drinking water requirements of domesticated animals are studied and described within the context of animal husbandry. However, relatively few studies have been focused on the drinking behavior of wild animals. A recent study has shown that feral pigeons do not discriminate drinking water according to its content of metabolic wastes, such as uric acid or urea (mimicking faeces-pollution by birds or urine-pollution by mammals respectively).
The "Joint Monitoring Programme for Water Supply, Sanitation and Hygiene (JMP) was established in 1990. [JMP publishes] "regular global updates throughout the Millennium Development Goal period. This report is the first update of the SDG period." "Eight out of ten people (5.8 billion) used improved sources with water available when needed. 5. Three out of four people (5.4 billion) used improved sources located on premises. 6. Three out of four people (5.4 billion) used improved sources free from contamination. 7. 89 per cent of the global population (6.5 billion people) used at least a basic service; that is, an improved source within 30 minutes’ round trip to collect water. 8. 844 million people still lacked even a basic drinking water service. 9. 263 million people spent over 30 minutes per round trip to collect water from an improved source (constituting a limited drinking water service). 10. 159 million people still collected drinking water directly from surface water sources, 58% lived in sub-Saharan Africa."
Proposition 65 (formally titled The Safe Drinking Water and Toxic Enforcement Act of 1986) is a California law passed by direct voter initiative in 1986 by a 63%–37% vote. Its goals are to protect drinking water sources from toxic substances that cause cancer and birth defects and to reduce or eliminate exposures to those chemicals generally, for example in consumer products, by requiring warnings in advance of those exposures.Arsenic
Arsenic is a chemical element with symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but only the gray form, which has a metallic appearance, is important to industry.
The primary use of arsenic is in alloys of lead (for example, in car batteries and ammunition). Arsenic is a common n-type dopant in semiconductor electronic devices, and the optoelectronic compound gallium arsenide is the second most commonly used semiconductor after doped silicon. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining due to the toxicity of arsenic and its compounds.A few species of bacteria are able to use arsenic compounds as respiratory metabolites. Trace quantities of arsenic are an essential dietary element in rats, hamsters, goats, chickens, and presumably other species. A role in human metabolism is not known. However, arsenic poisoning occurs in multicellular life if quantities are larger than needed. Arsenic contamination of groundwater is a problem that affects millions of people across the world.
The United States' Environmental Protection Agency states that all forms of arsenic are a serious risk to human health. The United States' Agency for Toxic Substances and Disease Registry ranked arsenic as number 1 in its 2001 Priority List of Hazardous Substances at Superfund sites. Arsenic is classified as a Group-A carcinogen.Bottled water
Bottled water is drinking water (e.g., well water, distilled water, mineral water, or spring water) packaged in plastic or glass water bottles. Bottled water may be carbonated or not. Sizes range from small single serving bottles to large carboys for water coolers.Distilled water
Distilled water is water that has been boiled into vapor and condensed back into liquid in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container. Thus, distilled water is one type of purified water.Drinking fountain
A bubbler also called a drinking fountain or water fountain, is a fountain designed to provide drinking water. It consists of a basin with either continuously running water or a tap. The drinker bends down to the stream of water and swallows water directly from the stream. Modern indoor drinking fountains may incorporate filters to remove impurities from the water and chillers to lower its temperature. Drinking fountains are usually found in public places, like schools, rest areas, libraries, and grocery stores. Many jurisdictions require drinking fountains to be wheelchair accessible (by sticking out horizontally from the wall), and to include an additional unit of a lower height for children and short adults. The design that this replaced often had one spout atop a refrigeration unit.
Use of the words water fountain and drinking fountain vary across regional dialects of English.Drinking water supply and sanitation in the United States
Issues that affect drinking water supply and sanitation in the United States include water scarcity, pollution, a backlog of investment, concerns about the affordability of water for the poorest, and a rapidly retiring workforce. Increased variability and intensity of rainfall as a result of climate change is expected to produce both more severe droughts and flooding, with potentially serious consequences for water supply and for pollution from combined sewer overflows. Droughts are likely to particularly affect the 66 percent of Americans whose communities depend on surface water. As for drinking water quality, there are concerns about disinfection by-products, lead, perchlorates and pharmaceutical substances, but generally drinking water quality in the U.S. is good.
Cities, utilities, state governments and the federal government have addressed the above issues in various ways. To keep pace with demand from an increasing population, utilities traditionally have augmented supplies. However, faced with increasing costs and droughts, water conservation is beginning to receive more attention and is being supported through the federal WaterSense program. The reuse of treated wastewater for non-potable uses is also becoming increasingly common. Pollution through wastewater discharges, a major issue in the 1960s, has been brought largely under control.
Most Americans are served by publicly owned water and sewer utilities. Any public system, which is defined as a system that serves more than 25 customers or 15 service connections, is regulated by the U.S. Environmental Protection Agency under the Safe Water Drinking Act. Eleven percent of Americans receive water from private (so-called "investor-owned") utilities. In rural areas, cooperatives often provide drinking water. Finally, up to 15 percent of Americans are served by their own wells. Water supply and wastewater systems are regulated by state governments and the federal government. At the state level, health and environmental regulation is entrusted to the corresponding state-level departments. Public Utilities Commissions or Public Service Commissions regulate tariffs charged by private utilities. In some states they also regulate tariffs by public utilities. At the federal level, drinking water quality and wastewater discharges are regulated by the Environmental Protection Agency (EPA), which also provides funding to utilities through State Revolving Funds.
Water consumption in the United States is more than double that in Central Europe, with large variations among the states. In 2002 the average American family spent $474 on water and sewerage charges, which is about the same level as in Europe. The median household spent about 1.1 percent of its income on water and sewage. By 2018, 87% of the American population receives water from publicly-owned water companies.Jordalsvatnet
Jordalsvatnet is a lake in the municipality of Bergen in Hordaland county, Norway. The 0.57-square-kilometre (140-acre) artificial lake has a small dam on the western end and it is the main source of drinking water for the borough of Åsane (population: 40,000) in the city of Bergen, as well as the Ytre Sandviken parts of the neighboring Bergenhus borough. The lake lies east of the village of Eidsvåg, with the European route E39 highway running along the western shoreline. The surrounding valley of Jordalen is primarily agricultural in nature.
In May 2005, a new water treatment plant along the lake opened in order to improve the quality of the drinking water. The untreated water coming out of the lake is lower than in other drinking water sources in the Bergen area due to the agricultural activity in the Jordalen valley.Ministry of Drinking Water and Sanitation
The Ministry of Drinking Water and Sanitation is a ministry of the Government of India.
In 1999, the Department of Drinking Water Supply (DDWS) was formed under Ministry of Rural Development, for focused attention on drinking water and sanitation. Later was renamed as Department of Drinking Water and Sanitation in 2010 and in 2011, it was conferred the Ministry status, keeping in view the extreme importance given to the sector by the United Progressive Alliance government. The Ministry of Drinking Water and Sanitation is the nodal department for the overall policy, planning, funding and coordination of programmes of drinking water and sanitation in the country.Nitrate
Nitrate is a polyatomic ion with the molecular formula NO−3 and a molecular mass of 62.0049 u. Organic compounds that contain the nitrate ester as a functional group (RONO2) are also called nitrates.Safe Drinking Water Act
The Safe Drinking Water Act (SDWA) is the principal federal law in the United States intended to ensure safe drinking water for the public. Pursuant to the act, the Environmental Protection Agency (EPA) is required to set standards for drinking water quality and oversee all states, localities, and water suppliers that implement the standards.
The SDWA applies to every public water system (PWS) in the United States. There are currently over 151,000 public water systems providing water to almost all Americans at some time in their lives. The Act does not cover private wells.The SDWA does not apply to bottled water. Bottled water is regulated by the Food and Drug Administration (FDA), under the Federal Food, Drug, and Cosmetic Act.Sebil (fountain)
A sebil or sabil (Arabic: سبيل; Turkish: sebil) is a small kiosk where water is freely dispensed to members of the public. Historically, it is a structure of both civic and religious importance in Muslim cities, most characteristically under the Ottoman Empire, but also in other regions and periods such as Mamluk Cairo. It is sometimes also used to refer to simple fountains for drinking water. Sebils were built at crossroads, in the middle of city squares, and on the outside of mosques and other religious complexes throughout the Ottoman Empire to provide drinking water for travelers and enable ritual purification (ablutions) before prayer.Svartediket
Svartediket is a lake in the city of Bergen in Hordaland county, Norway. The 0.5-square-kilometre (0.19 sq mi) lake lies immediately north of the mountain Ulriken, northeast of the Store Lungegårdsvannet bay. Historically, this lake was called Ålrekstadsvannet, but in the late 19th century, a dam was built on the south end of the lake to create a reservoir for the city's drinking water. Since then it was called Svartediket, after the water plant built there.The lake is the main source of drinking water for the central parts of the city of Bergen. There is a pumping station and treatment facility build adjacent to the lake inside the mountain Ulriken. Drinking water is collected at a 28-metre (92 ft) depth in Svartediket. Inside the water treatment plant, the water is filtered and irradiated with UV light to kill harmful microorganisms. After treatment, the clean drinking water is stored in a 15,000-cubic-metre (530,000 cu ft) large water pool inside the mountain. This is the water that is pumped down to the city center for drinking water. In 2004, Bergen was hit by a Giardia lamblia epidemic which had its source in the lake Svartediket. The water treatment facility was upgraded in 2007.Water chlorination
Water chlorination is the process of adding chlorine or chlorine compounds such as sodium hypochlorite to water. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, and typhoid.Water fluoridation
Water fluoridation is the controlled addition of fluoride to a public water supply to reduce tooth decay. Fluoridated water contains fluoride at a level that is effective for preventing cavities; this can occur naturally or by adding fluoride. Fluoridated water operates on tooth surfaces: in the mouth, it creates low levels of fluoride in saliva, which reduces the rate at which tooth enamel demineralizes and increases the rate at which it remineralizes in the early stages of cavities. Typically a fluoridated compound is added to drinking water, a process that in the U.S. costs an average of about $1.08 per person-year. Defluoridation is needed when the naturally occurring fluoride level exceeds recommended limits. In 2011 the World Health Organization suggested a level of fluoride from 0.5 to 1.5 mg/L (milligrams per litre), depending on climate, local environment, and other sources of fluoride. Bottled water typically has unknown fluoride levels.Tooth decay remains a major public health concern in most industrialized countries, affecting 60–90% of schoolchildren and the vast majority of adults. Water fluoridation reduces cavities in children, while efficacy in adults is less clear. A Cochrane review estimates a reduction in cavities when water fluoridation was used by children who had no access to other sources of fluoride to be 35% in baby teeth and 26% in permanent teeth. The evidence quality was poor. Most European countries have experienced substantial declines in tooth decay without its use, however milk and salt fluoridation is widespread. Recent studies suggest that water fluoridation, particularly in industrialized nations, may be unnecessary because topical fluorides (such as in toothpaste) are widely used, and caries rates have become low.Although fluoridation can cause dental fluorosis, which can alter the appearance of developing teeth or enamel fluorosis, the differences are mild and usually not considered to be of aesthetic or public health concern. There is no clear evidence of other adverse effects from water fluoridation. Fluoride's effects depend on the total daily intake of fluoride from all sources. Drinking water is typically the largest source; other methods of fluoride therapy include fluoridation of toothpaste, salt, and milk. The views on the most efficient method for community prevention of tooth decay are mixed. The Australian government states that water fluoridation is the most effective way to achieve fluoride exposure that is community-wide. The World Health Organization reports that water fluoridation, when feasible and culturally acceptable, has substantial advantages, especially for subgroups at high risk, while the European Commission finds no benefit to water fluoridation compared with topical use.Public water fluoridation was first practiced in the U.S. As of 2012, 25 countries have artificial water fluoridation to varying degrees, 11 of them have more than 50% of their population drinking fluoridated water. A further 28 countries have water that is naturally fluoridated, though in many of them the fluoride is above the optimal level. As of 2012, about 435 million people worldwide received water fluoridated at the recommended level (i.e., about 5.4% of the global population). About 214 million of them living in the United States. Major health organizations such as the World Health Organization and FDI World Dental Federation supported water fluoridation as safe and effective. The Centers for Disease Control and Prevention lists water fluoridation as one of the ten great public health achievements of the 20th century in the U.S. Despite this, the practice is controversial as a public health measure. Some countries and communities have discontinued fluoridation, while others have expanded it. Opponents of the practice argue that neither the benefits nor the risks have been studied adequately, and debate the conflict between what might be considered mass medication and individual liberties.Water pollution
Water pollution is the contamination of water bodies, usually as a result of human activities. Water bodies include for example lakes, rivers, oceans, aquifers and groundwater. Water pollution results when contaminants are introduced into the natural environment. For example, releasing inadequately treated wastewater into natural water bodies can lead to degradation of aquatic ecosystems. In turn, this can lead to public health problems for people living downstream. They may use the same polluted river water for drinking or bathing or irrigation. Water pollution is the leading worldwide cause of death and disease, e.g. due to water-borne diseases.Water pollution can be grouped into surface water pollution. Marine pollution and nutrient pollution are subsets of water pollution. Sources of water pollution are either point sources and non-point sources. Point sources have one identifiable cause of the pollution, such as a storm drain, wastewater treatment plant or stream. Non-point sources are more diffuse, such as agricultural runoff. Pollution is the result of the cumulative effect over time. All plants and organisms living in or being exposed to polluted water bodies can be impacted. The effects can damage individual species and impact the natural biological communities they are part of.
The causes of water pollution include a wide range of chemicals and pathogens as well as physical parameters. Contaminants may include organic and inorganic substances. Elevated temperatures can also lead to polluted water. A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers. Elevated water temperatures decrease oxygen levels, which can kill fish and alter food chain composition, reduce species biodiversity, and foster invasion by new thermophilic species.Water pollution is measured by analysing water samples. Physical, chemical and biological tests can be done. Control of water pollution requires appropriate infrastructure and management plans. The infrastructure may include wastewater treatment plants. Sewage treatment plants and industrial wastewater treatment plants are usually required to protect water bodies from untreated wastewater. Agricultural wastewater treatment for farms, and erosion control from construction sites can also help prevent water pollution. Nature-based solutions are another approach to prevent water pollution. Effective control of urban runoff includes reducing speed and quantity of flow. In the United States, best management practices for water pollution include approaches to reduce the quantity of water and improve water quality.Water quality
Water quality refers to the chemical, physical, biological, and radiological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose. It is most frequently used by reference to a set of standards against which compliance, generally achieved through treatment of the water, can be assessed. The most common standards used to assess water quality relate to health of ecosystems, safety of human contact, and drinking water.Water supply and sanitation in Pakistan
Drinking water supply and sanitation in Pakistan is characterized by some achievements and many challenges. Despite high population growth the country has increased the share of the population with access to an improved water source from 85% in 1990 to 92% in 2010, although this does not necessarily mean that the water from these sources is safe to drink. The share with access to improved sanitation increased from 27% to 48% during the same period, according to the Joint Monitoring Program for Water Supply and Sanitation. There has also been considerable innovation at the grass-root level, in particular concerning sanitation. The Orangi Pilot Project in Karachi and community-led total sanitation in rural areas are two examples of such innovation.
However, the sector still faces major challenges. The quality of the services is poor, as evidenced by intermittent water supply in urban areas and limited wastewater treatment. Poor drinking water quality and sanitation lead to major outbreaks of waterborne diseases. major outbreaks of waterborne diseases swept the cities of Faisalabad, Karachi, Lahore and Peshawar in 2006. Estimates indicate that each year, more than three million Pakistanis become infected with waterborne diseases. In addition, many service providers do not even cover the costs of operation and maintenance due to low tariffs and poor efficiency. Consequently, the service providers strongly depend on government subsidies and external funding. A National Sanitation Policy and a National Drinking Water Policy have been approved in 2006 and 2009 respectively with the objective to improve water and sanitation coverage and quality. However, the level of annual investment (US$4/capita) still remains much below what would be necessary to achieve a significant increase in access and service quality.Water treatment
Water treatment is any process that improves the quality of water to make it more acceptable for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, including being safely returned to the environment. Water treatment removes contaminants and undesirable components, or reduces their concentration so that the water becomes fit for its desired end-use.Waterborne diseases
Waterborne diseases are conditions caused by pathogenic micro-organisms that are transmitted in water. Disease can be spread while bathing, washing or drinking water, or by eating food exposed to contaminated water. While diarrhea and vomiting are the most commonly reported symptoms of waterborne illness, other symptoms can include skin, ear, respiratory, or eye problems.Various forms of waterborne diarrheal disease are the most prominent examples, and affect children in developing countries most dramatically. According to the World Health Organization, waterborne diseases account for an estimated 3.6% of the total DALY (disability- adjusted life year) global burden of disease, and cause about 1.5 million human deaths annually. The World Health Organization estimates that 58% of that burden, or 842,000 deaths per year, is attributable to a lack of safe drinking water supply, sanitation and hygiene (summarized as WASH).The term waterborne disease is reserved largely for infections that predominantly are transmitted through contact with or consumption of infected water. Trivially, many infections may be transmitted by microbes or parasites that accidentally, possibly as a result of exceptional circumstances, have entered the water, but the fact that there might be an occasional freak infection need not mean that it is useful to categorise the resulting disease as "waterborne". Nor is it common practice to refer to diseases such as malaria as "waterborne" just because mosquitoes have aquatic phases in their life cycles, or because treating the water they inhabit happens to be an effective strategy in control of the mosquitoes that are the vectors.
Microorganisms causing diseases that characteristically are waterborne prominently include protozoa and bacteria, many of which are intestinal parasites, or invade the tissues or circulatory system through walls of the digestive tract. Various other waterborne diseases are caused by viruses. (In spite of philosophical difficulties associated with defining viruses as "organisms", it is practical and convenient to regard them as microorganisms in this connection.)
Yet other important classes of water-borne diseases are caused by metazoan parasites. Typical examples include certain Nematoda, that is to say "roundworms". As an example of water-borne Nematode infections, one important waterborne nematodal disease is Dracunculiasis. It is acquired by swallowing water in which certain copepoda occur that act as vectors for the Nematoda. Anyone swallowing a copepod that happens to be infected with Nematode larvae in the genus Dracunculus, becomes liable to infection. The larvae cause guinea worm disease.Another class of waterborne metazoan pathogens are certain members of the Schistosomatidae, a family of blood flukes. They usually infect victims that make skin contact with the water. Blood flukes are pathogens that cause Schistosomiasis of various forms, more or less seriously affecting hundreds of millions of people worldwide.Long before modern studies had established the germ theory of disease, or any advanced understanding of the nature of water as a vehicle for transmitting disease, traditional beliefs had cautioned against the consumption of water, rather favouring processed beverages such as beer, wine and tea. For example, in the camel caravans that crossed Central Asia along the Silk Road, the explorer Owen Lattimore noted, "The reason we drank so much tea was because of the bad water. Water alone, unboiled, is never drunk. There is a superstition that it causes blisters on the feet."