In 2010, about 56% of the global population (5.9 billion people) had access to piped water supply through house connections or to an improved water source through other means than house, including standpipes, water kiosks, spring supplies and protected wells. However, about 13% (about 900 million people) did not have access to an improved water source and had to use unprotected wells or springs, canals, lakes or rivers for their water needs.
A clean water supply—in particular, water that is not polluted with fecal matter from lack of sanitation—is the single most important determinant of public health. Destruction of water supply and/or sanitation infrastructure after major catastrophes (earthquakes, floods, war, etc.) poses the immediate threat of severe epidemics of waterborne diseases, several of which can be life-threatening.
Water supply systems get water from a variety of locations after appropriate treatment, including groundwater (aquifers), surface water (lakes and rivers), and the sea through desalination. The water treatment steps include, in most cases, purification, disinfection through chlorination and sometimes fluoridation. Treated water then either flows by gravity or is pumped to reservoirs, which can be elevated such as water towers or on the ground (for indicators related to the efficiency of drinking water distribution see non-revenue water). Once water is used, wastewater is typically discharged in a sewer system and treated in a sewage treatment plant before being discharged into a river, lake or the sea or reused for landscaping, irrigation or industrial use (see also sanitation).
In the United States, the typical single family home uses about 520 l (138 US gal) of water per day (2016 estimate) or 222 l (58.6 US gal) per capita per day. This includes several common residential end use purposes (in decreasing order) like toilet use, showers, tap (faucet) use, washing machine use, leaks, other (unidentified), baths, and dishwasher use.
Water supply service quality has many dimensions: continuity; water quality; pressure; and the degree of responsiveness of service providers to customer complaints. Many people in developing countries receive a poor or very poor quality of service.
Continuity of water supply is taken for granted in most developed countries, but is a severe problem in many developing countries, where sometimes water is only provided for a few hours every day or a few days a week. It is estimated that about half of the population of developing countries receives water on an intermittent basis.
Drinking water quality has a micro-biological and a physico-chemical dimension. There are thousands of parameters of water quality. In public water supply systems water should, at a minimum, be disinfected—most commonly through the use of chlorination or the use of ultra violet light—or it may need to undergo treatment, especially in the case of surface water. For more details, please see the separate entries on water quality, water treatment and drinking water.
Water pressures vary in different locations of a distribution system. Water mains below the street may operate at higher pressures, with a pressure reducer located at each point where the water enters a building or a house. In poorly managed systems, water pressure can be so low as to result only in a trickle of water or so high that it leads to damage to plumbing fixtures and waste of water. Pressure in an urban water system is typically maintained either by a pressurised water tank serving an urban area, by pumping the water up into a water tower and relying on gravity to maintain a constant pressure in the system or solely by pumps at the water treatment plant and repeater pumping stations.
Typical UK pressures are 4–5 bar (60-70 PSI) for an urban supply. However, some people can get over eight bars or below one bar. A single iron main pipe may cross a deep valley, it will have the same nominal pressure, however each consumer will get a bit more or less because of the hydrostatic pressure (about 1 bar/10 m height). So people at the bottom of a 30-metre (100 ft) hill will get about 3 bars more than those at the top.
The effective pressure also varies because of the pressure loss due to supply resistance even for the same static pressure. An urban consumer may have 5 metres of 15 mm pipe running from the iron main, so the kitchen tap flow will be fairly unrestricted, so high flow. A rural consumer may have a kilometre of rusted and limed 22 mm iron pipe, so their kitchen tap flow will be small.
For this reason, the UK domestic water system has traditionally (prior to 1989) employed a "cistern feed" system, where the incoming supply is connected to the kitchen sink and also a header/storage tank in the attic. Water can dribble into this tank through a 12 mm pipe, plus ball valve, and then supply the house on 22 or 28 mm pipes. Gravity water has a small pressure (say ¼ bar in the bathroom) so needs wide pipes to allow for higher flows. This is fine for baths and toilets but is frequently inadequate for showers. A booster pump or a hydrophore is installed to increase and maintain pressure. For this reason urban houses are increasingly using mains pressure boilers (combies) which take a long time to fill a bath but suit the high back pressure of a shower.
A great variety of institutions have responsibilities in water supply. A basic distinction is between institutions responsible for policy and regulation on the one hand; and institutions in charge of providing services on the other hand.
Water supply policies and regulation are usually defined by one or several Ministries, in consultation with the legislative branch. In the United States the United States Environmental Protection Agency, whose administrator reports directly to the President, is responsible for water and sanitation policy and standard setting within the executive branch. In other countries responsibility for sector policy is entrusted to a Ministry of Environment (such as in Mexico and Colombia), to a Ministry of Health (such as in Panama, Honduras and Uruguay), a Ministry of Public Works (such as in Ecuador and Haiti), a Ministry of Economy (such as in German states) or a Ministry of Energy (such as in Iran). A few countries, such as Jordan and Bolivia, even have a Ministry of Water. Often several Ministries share responsibilities for water supply.
In the European Union, important policy functions have been entrusted to the supranational level. Policy and regulatory functions include the setting of tariff rules and the approval of tariff increases; setting, monitoring and enforcing norms for quality of service and environmental protection; benchmarking the performance of service providers; and reforms in the structure of institutions responsible for service provision. The distinction between policy functions and regulatory functions is not always clear-cut. In some countries they are both entrusted to Ministries, but in others regulatory functions are entrusted to agencies that are separate from Ministries.
Dozens of countries around the world have established regulatory agencies for infrastructure services, including often water supply and sanitation, in order to better protect consumers and to improve efficiency. Regulatory agencies can be entrusted with a variety of responsibilities, including in particular the approval of tariff increases and the management of sector information systems, including benchmarking systems. Sometimes they also have a mandate to settle complaints by consumers that have not been dealt with satisfactorily by service providers. These specialized entities are expected to be more competent and objective in regulating service providers than departments of government Ministries. Regulatory agencies are supposed to be autonomous from the executive branch of government, but in many countries have often not been able to exercise a great degree of autonomy.
In the United States regulatory agencies for utilities have existed for almost a century at the level of states, and in Canada at the level of provinces. In both countries they cover several infrastructure sectors. In many U.S. states they are called Public Utility Commissions. For England and Wales, a regulatory agency for water (OFWAT) was created as part of the privatization of the water industry in 1989. In many developing countries, water regulatory agencies were created during the 1990s in parallel with efforts at increasing private sector participation. (for more details on regulatory agencies in Latin America, for example, please see Water and sanitation in Latin America and the regional association of water regulatory agencies ADERASA.)
Many countries do not have regulatory agencies for water. In these countries service providers are regulated directly by local government, or the national government. This is, for example, the case in the countries of continental Europe, in China and India.
Water supply service providers, which are often utilities, differ from each other in terms of their geographical coverage relative to administrative boundaries; their sectoral coverage; their ownership structure; and their governance arrangements.
Many water utilities provide services in a single city, town or municipality. However, in many countries municipalities have associated in regional or inter-municipal or multi-jurisdictional utilities to benefit from economies of scale. In the United States these can take the form of special-purpose districts which may have independent taxing authority. An example of a multi-jurisdictional water utility in the United States is WASA, a utility serving Washington, D.C. and various localities in the state of Maryland. Multi-jurisdictional utilities are also common in Germany, where they are known as "Zweckverbaende", in France and in Italy.
In some federal countries, there are water service providers covering most or all cities and towns in an entire state, such as in all states of Brazil and some states in Mexico (see Water supply and sanitation in Mexico). In England and Wales, water supply and sewerage is supplied almost entirely through ten regional companies. Some smaller countries, especially developed countries, have established service providers that cover the entire country or at least most of its cities and major towns. Such national service providers are especially prevalent in West Africa and Central America, but also exist, for example, in Tunisia, Jordan and Uruguay (see also water supply and sanitation in Uruguay). In rural areas, where about half the world population lives, water services are often not provided by utilities, but by community-based organizations which usually cover one or sometimes several villages.
Some water utilities provide only water supply services, while sewerage is under the responsibility of a different entity. This is for example the case in Tunisia. However, in most cases water utilities also provide sewer and sewage treatment services. In some cities or countries utilities also distribute electricity. In a few cases such multi-utilities also collect solid waste and provide local telephone services. An example of such an integrated utility can be found in the Colombian city of Medellín. Utilities that provide water, sanitation and electricity can be found in Frankfurt, Germany (Mainova), in Casablanca, Morocco and in Gabon in West Africa. Multi-utilities provide certain benefits such as common billing and the option to cross-subsidize water services with revenues from electricity sales, if permitted by law.
Water supply providers can be either public, private, mixed or cooperative. Most urban water supply services around the world are provided by public entities. As Willem-Alexander, Prince of Orange (2002) stated, "The water crisis that is affecting so many people is mainly a crisis of governance—not of water scarcity." The introduction of cost-reflective tariffs together with cross-subsidization between richer and poorer consumers is an essential governance reform in order to reduce the high levels of Unaccounted-for Water (UAW) and to provide the finance needed to extend the network to those poorest households who remain unconnected. Partnership arrangements between the public and private sector can play an important role in order to achieve this objective.
An estimated 10 percent of urban water supply is provided by private or mixed public-private companies, usually under concessions, leases or management contracts. Under these arrangements the public entity that is legally responsible for service provision delegates certain or all aspects of service provision to the private service provider for a period typically ranging from 4 to 30 years. The public entity continues to own the assets. These arrangements are common in France and in Spain. Only in few parts of the world water supply systems have been completely sold to the private sector (privatization), such as in England and Wales as well as in Chile. The largest private water companies in the world are Suez and Veolia Environnement from France; Aguas de Barcelona from Spain; and Thames Water from the UK, all of which are engaged internationally (see links to website of these companies below). In recent years, a number of cities have reverted to the public sector in a process called "remunicipalization".
90% of urban water supply and sanitation services are currently in the public sector. They are owned by the state or local authorities, or also by collectives or cooperatives. They run without an aim for profit but are based on the ethos of providing a common good considered to be of public interest. In most middle and low-income countries, these publicly owned and managed water providers can be inefficient as a result of political interference, leading to over-staffing and low labor productivity.
Ironically, the main losers from this institutional arrangement are the urban poor in these countries. Because they are not connected to the network, they end up paying far more per liter of water than do more well-off households connected to the network who benefit from the implicit subsidies that they receive from loss-making utilities.
The fact that we are still so far from achieving universal access to clean water and sanitation shows that public water authorities, in their current state, are not working well enough. Yet some are being very successful and are modelling the best forms of public management. As Ryutaro Hashimoto, former Japanese Prime Minister, notes: "Public water services currently provide more than 90 percent of water supply in the world. Modest improvement in public water operators will have immense impact on global provision of services."
Governance arrangements for both public and private utilities can take many forms (Kurian and McCarney, 2010). Governance arrangements define the relationship between the service provider, its owners, its customers and regulatory entities. They determine the financial autonomy of the service provider and thus its ability to maintain its assets, expand services, attract and retain qualified staff, and ultimately to provide high-quality services. Key aspects of governance arrangements are the extent to which the entity in charge of providing services is insulated from arbitrary political intervention; and whether there is an explicit mandate and political will to allow the service provider to recover all or at least most of its costs through tariffs and retain these revenues. If water supply is the responsibility of a department that is integrated in the administration of a city, town or municipality, there is a risk that tariff revenues are diverted for other purposes. In some cases, there is also a risk that staff are appointed mainly on political grounds rather than based on their professional credentials.
International standards for water supply system are covered by International Classification of Standards (ICS) 91.140.60.
Comparing the performance of water and sanitation service providers (utilities) is needed, because the sector offers limited scope for direct competition (natural monopoly). Firms operating in competitive markets are under constant pressure to out perform each other. Water utilities are often sheltered from this pressure, and it frequently shows: some utilities are on a sustained improvement track, but many others keep falling further behind best practice. Benchmarking the performance of utilities allows the stimulation of competition, establish realistic targets for improvement and create pressure to catch up with better utilities. Information on benchmarks for water and sanitation utilities is provided by the International Benchmarking Network for Water and Sanitation Utilities.
The cost of supplying water consists, to a very large extent, of fixed costs (capital costs and personnel costs) and only to a small extent of variable costs that depend on the amount of water consumed (mainly energy and chemicals). The full cost of supplying water in urban areas in developed countries is about US$1–2 per cubic meter depending on local costs and local water consumption levels. The cost of sanitation (sewerage and wastewater treatment) is another US$1–2 per cubic meter. These costs are somewhat lower in developing countries. Throughout the world, only part of these costs is usually billed to consumers, the remainder being financed through direct or indirect subsidies from local, regional or national governments (see section on tariffs).
Besides subsidies water supply investments are financed through internally generated revenues as well as through debt. Debt financing can take the form of credits from commercial Banks, credits from international financial institutions such as the World Bank and regional development banks (in the case of developing countries), and bonds (in the case of some developed countries and some upper middle-income countries).
Almost all service providers in the world charge tariffs to recover part of their costs. According to estimates by the World Bank the average (mean) global water tariff is US$0.53 per cubic meter. In developed countries the average tariff is US$1.04, while it is only U$0.11 in the poorest developing countries. The lowest tariffs in developing countries are found in South Asia (mean of US$0.09/m3), while the highest are found in Latin America (US$0.41/m3). Data for 132 cities were assessed. The tariff is estimate for a consumption level of 15 cubic meters per month. Few utilities do recover all their costs. According to the same World Bank study only 30% of utilities globally, and only 50% of utilities in developed countries, generate sufficient revenue to cover operation, maintenance and partial capital costs.
According to another study undertaken in 2006 by NUS Consulting, the average water and sewerage tariff in 14 mainly OECD countries excluding VAT varied between US$0.66 per cubic meter in the United States and the equivalent of US$2.25 per cubic meter in Denmark. However, water consumption is much higher in the US than in Europe. Therefore, residential water bills may be very similar, even if the tariff per unit of consumption tends to be higher in Europe than in the US.
A typical family on the US East Coast paid between US$30 and US$70 per month for water and sewer services in 2005.
In developing countries, tariffs are usually much further from covering costs. Residential water bills for a typical consumption of 15 cubic meters per month vary between less than US$1 and US$12 per month.
Water and sanitation tariffs, which are almost always billed together, can take many different forms. Where meters are installed, tariffs are typically volumetric (per usage), sometimes combined with a small monthly fixed charge. In the absence of meters, flat or fixed rates — which are independent of actual consumption — are being charged. In developed countries, tariffs are usually the same for different categories of users and for different levels of consumption.
In developing countries, the situation is often characterized by cross-subsidies with the intent to make water more affordable for residential low-volume users that are assumed to be poor. For example, industrial and commercial users are often charged higher tariffs than public or residential users. Also, metered users are often charged higher tariffs for higher levels of consumption (increasing-block tariffs). However, cross-subsidies between residential users do not always reach their objective. Given the overall low level of water tariffs in developing countries even at higher levels of consumption, most consumption subsidies benefit the wealthier segments of society. Also, high industrial and commercial tariffs can provide an incentive for these users to supply water from other sources than the utility (own wells, water tankers) and thus actually erode the utility's revenue base.
Metering of water supply is usually motivated by one or several of four objectives: First, it provides an incentive to conserve water which protects water resources (environmental objective). Second, it can postpone costly system expansion and saves energy and chemical costs (economic objective). Third, it allows a utility to better locate distribution losses (technical objective). Fourth, it allows suppliers to charge for water based on use, which is perceived by many as the fairest way to allocate the costs of water supply to users. Metering is considered good practice in water supply and is widespread in developed countries, except for the United Kingdom. In developing countries it is estimated that half of all urban water supply systems are metered and the tendency is increasing.
Water meters are read by one of several methods:
Most cities are increasingly installing Automatic Meter Reading (AMR) systems to prevent fraud, to lower ever-increasing labor and liability costs and to improve customer service and satisfaction.
Examples of contamination include:
Examples of chemical contamination include:
Throughout history, people have devised systems to make getting and using water more convenient. Living in semi-arid regions, ancient Persians in the 1st millennium BC used qanat system to gain access to water in the mountains. Early Rome had indoor plumbing, meaning a system of aqueducts and pipes that terminated in homes and at public wells and fountains for people to use.
Until the Enlightenment era, little progress was made in water supply and sanitation and the engineering skills of the Romans were largely neglected throughout Europe. It was in the 18th century that a rapidly growing population fueled a boom in the establishment of private water supply networks in London. The Chelsea Waterworks Company was established in 1723 "for the better supplying the City and Liberties of Westminster and parts adjacent with water". Other waterworks were established in London, including at West Ham in 1743, at Lea Bridge before 1767, Lambeth Waterworks Company in 1785, West Middlesex Waterworks Company in 1806 and Grand Junction Waterworks Company in 1811.
The S-bend pipe was invented by Alexander Cummings in 1775 but became known as the U-bend following the introduction of the U-shaped trap by Thomas Crapper in 1880. The first screw-down water tap was patented in 1845 by Guest and Chrimes, a brass foundry in Rotherham.
In ancient Peru, the Nazca people employed a system of interconnected wells and an underground watercourse known as puquios. In Spain and Spanish America, a community operated watercourse known as an acequia, combined with a simple sand filtration system, provided potable water. Beginning in the Roman era a water wheel device known as a noria supplied water to aqueducts and other water distribution systems in major cities in Europe and the Middle East. London water supply infrastructure developed over many centuries from early mediaeval conduits, through major 19th-century treatment works built in response to cholera threats, to modern, large-scale reservoirs.
Water towers appeared around the late 19th century; as building height rose, and steam, electric and diesel-powered water pumps became available. As skyscrapers appeared, they needed rooftop water towers.
The technique of purification of drinking water by use of compressed liquefied chlorine gas was developed in 1910 by U.S. Army Major (later Brig. Gen.) Carl Rogers Darnall (1867–1941), professor of chemistry at the Army Medical School. Shortly thereafter, Major (later Col.) William J. L. Lyster (1869–1947) of the Army Medical Department used a solution of calcium hypochlorite in a linen bag to treat water. For many decades, Lyster's method remained the standard for U.S. ground forces in the field and in camps, implemented in the form of the familiar Lyster Bag (also spelled Lister Bag). Darnall's work became the basis for present day systems of municipal water purification.
Desalination appeared during the late 20th century, and is still limited to a few areas.
During the beginning of the 21st Century, especially in areas of urban and suburban population centers, traditional centralized infrastructure have not been able to supply sufficient quantities of water to keep up with growing demand. Among several options that have been managed are the extensive use of desalination technology, this is especially prevalent in coastal areas and in "dry" countries like Australia. Decentralization of water infrastructure has grown extensively as a viable solution including Rainwater harvesting and Stormwater harvesting where policies are eventually tending towards a more rational use and sourcing of water incorporation concepts such as "Fit for Purpose". Emirians have the highest per capita water consumption rate in the world, at 133 gallons.
The first documented use of sand filters to purify the water supply dates to 1804, when the owner of a bleachery in Paisley, Scotland, John Gibb, installed an experimental filter, selling his unwanted surplus to the public. The first treated public water supply in the world was installed by engineer James Simpson for the Chelsea Waterworks Company in London in 1829. The practice of water treatment soon became mainstream, and the virtues of the system were made starkly apparent after the investigations of the physician John Snow during the 1854 Broad Street cholera outbreak demonstrated the role of the water supply in spreading the cholera epidemic.
The Metropolis Water Act introduced regulation of the water supply companies in London, including minimum standards of water quality for the first time. The Act "made provision for securing the supply to the Metropolis of pure and wholesome water", and required that all water be "effectually filtered" from 31 December 1855. This legislation set a worldwide precedent for similar state public health interventions across Europe.
Permanent water chlorination began in 1905, when a faulty slow sand filter and a contaminated water supply led to a serious typhoid fever epidemic in Lincoln, England. Dr. Alexander Cruickshank Houston used chlorination of the water to stem the epidemic. His installation fed a concentrated solution of chloride of lime to the water being treated. The first continuous use of chlorine in the United States for disinfection took place in 1908 at Boonton Reservoir (on the Rockaway River), which served as the supply for Jersey City, New Jersey. Desalination appeared during the late 20th century, and is still limited to a few areas.
The technique of purification of drinking water by use of compressed liquefied chlorine gas was developed by a British officer in the Indian Medical Service, Vincent B. Nesfield, in 1903. U.S. Army Major Carl Rogers Darnall, Professor of Chemistry at the Army Medical School, gave the first practical demonstration of this in 1910. This work became the basis for present day systems of municipal water purification.
Water supply issues have specific adverse effects on women in developing nations. Women are often the primary family member responsible for providing water as well as collecting it. Inclusion of women in the design and implementation of water supply projects is an area of concern currently being addressed by multiple world organizations.
An aqueduct is a watercourse constructed to carry water from a source to a distribution point far away. In modern engineering, the term aqueduct is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose. The term aqueduct also often refers specifically to a bridge on an artificial watercourse. The word is derived from the Latin aqua ("water") and ducere ("to lead"). Aqueducts were used in ancient Greece, ancient Egypt, and ancient Rome. In modern times, the largest aqueducts of all have been built in the United States to supply the country's biggest cities. The simplest aqueducts are small ditches cut into the earth. Much larger channels may be used in modern aqueducts. Aqueducts sometimes run for some or all of their path through tunnels constructed underground. Modern aqueducts may also use pipelines. Historically, agricultural societies have constructed aqueducts to irrigate crops and supply large cities with drinking water.Chennai MetroWater Supply and Sewage Board
Chennai Metropolitan Water Supply and Sewerage Board known as CMWSSB provides Water supply and sewage treatment to the city of Chennai and areas around it.
Chennai is one of the metros in India which is dependent mostly on ground water supply. Ground water in Chennai is replenished by rain water and average rainfall in Chennai is 1276 mm. Chennai receives about 985 million liters per day (mld) from various sources against the required amount of 1200 mld and the demand is expected to rise to 2100 mld by 2031. The newly constructed Minjur desalination plant adds another 100 mlds to the city's growing demand.
As of 2012, Chennai Metrowater supplies about 830 million litres of water every day to residents and commercial establishments.Cistern
A cistern (Middle English cisterne, from Latin cisterna, from cista, "box", from Greek κίστη kistê, "basket") is a waterproof receptacle for holding liquids, usually water. Cisterns are often built to catch and store rainwater. Cisterns are distinguished from wells by their waterproof linings. Modern cisterns range in capacity from a few litres to thousands of cubic metres, effectively forming covered reservoirs.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.History of water supply and sanitation
The history of water supply and sanitation is one of a logistical challenge to provide clean water and sanitation systems since the dawn of civilization. Where water resources, infrastructure or sanitation systems were insufficient, diseases spread and people fell sick or died prematurely.
Major human settlements could initially develop only where fresh surface water was plentiful, such as near rivers or natural springs. Throughout history, people have devised systems to make getting water into their communities and households and disposing (and later also treating) wastewater more conveniently.The historical focus of sewage treatment was on the conveyance of raw sewage to a natural body of water, e.g. a river or ocean, where it would be diluted and dissipated. Early human habitations were often built next to water sources. Rivers would often serve as a crude form of natural sewage disposal.
Over the millennia, technology has dramatically increased the distances across which water can be relocated. Furthermore, treatment processes to purify drinking water and to treat wastewater have been improved.ISO 7027
ISO 7027:1999 is an ISO standard for water quality that enables the determination of turbidity. The ISO 7027 technique is used to determine the concentration of suspended particles in a sample of water by measuring the incident light scattered at right angles from the sample. The scattered light is captured by a photodiode, which produces an electronic signal that is converted to a turbidity.New York City water supply system
For historic background on the NYC water supply system see Old Croton Aqueduct
New York City's water supply system is one of the most extensive municipal water systems in the world. This complex system relies on a combination of aqueducts, reservoirs, and tunnels to meet the daily needs of New York City's more than eight million residents and its many visitors.
Thanks to well-protected wilderness watersheds, New York's water treatment process is simpler than in other American cities. One advantage of the system is that 95% of the total water supply is supplied by gravity. The other 5% needs to be pumped to maintain pressure, but this is sometimes increased in times of drought when the reservoirs are at lower than normal levels.The city has sought to restrict development throughout its watershed. One of its largest watershed protection programs is the Land Acquisition Program, under which the New York City Department of Environmental Protection (DEP) has purchased or protected, through conservation easement, over 130,000 acres (53,000 ha) since 1997.Rainwater harvesting
Rainwater harvesting is the accumulation and storage of rainwater for reuse on-site, rather than allowing it to run off. Rainwater can be collected from rivers or roofs, and in many places, the water collected is redirected to a deep pit (well, shaft, or borehole), a reservoir with percolation, or collected from dew or fog with nets or other tools. Its uses include water for gardens, livestock, irrigation, domestic use with proper treatment, indoor heating for houses, etc. The harvested water can also be used as drinking water, longer-term storage, and for other purposes such as groundwater recharge.
Rainwater harvesting is one of the simplest and oldest methods of self-supply of water for households usually financed by the user.Tap water
Tap water (running water, city water, town water, municipal water, etc.) is water supplied to a tap (valve). Its uses include drinking, washing, cooking, and the flushing of toilets. Indoor tap water is distributed through "indoor plumbing", which has existed since antiquity but was available to very few people until the second half of the 19th century when it began to spread in popularity in what are now developed countries. Tap water became common in many regions during the 20th century, and is now lacking mainly among people in poverty, especially in developing countries.
Tap water is often culturally assumed to be drinking water, especially in developed countries. Usually it is potable, although water quality problems are not rare. Household water purification methods such as water filters, boiling, or distillation can be used when tap water's potability is doubted. The application of technologies (such as water treatment plants) involved in providing clean water to homes, businesses, and public buildings is a major subfield of sanitary engineering. Calling a water supply "tap water" distinguishes it from the other main types of fresh water which may be available; these include water from rainwater-collecting cisterns, water from village pumps or town pumps, water from wells, or water carried from streams, rivers, or lakes (whose potability may vary).Water supply and sanitation in Bangladesh
In 1993, the country's groundwater, the source of drinking water for 97% of the rural population and a significant share of the urban population, was contaminated with arsenic. However, in 2004, 98% of the population already has access to an improved water source, a very high level for a low-income country. This has been achieved through the construction of hand pumps with the support of external donors.
Bangladesh has a low level of cost recovery due to low tariffs and poor economic efficiency, especially in urban areas where revenues from water sales do not cover operating costs.
Only 56% of the population was estimated to have access to adequate sanitation facilities in 2010. But a new approach to improve sanitation coverage in rural areas, namely the community-led total sanitation concept, was introduced in Bangladesh and is credited for having contributed significantly to the increase in sanitation coverage.The government has adopted policies that could remedy the challenges in the sector. These include the National Policies for Safe Water Supply and Sanitation, National Water Management Plan, the National Policy for Arsenic Mitigation which gives preference to surface water over groundwater and the National Sanitation Strategy of 2005. These policies emphasize decentralization, user participation, the role of women, and appropriate pricing rules.Water supply and sanitation in Brazil
Access to at least basic water increased from 94% to 97% between 2000 and 2015; an increase in access to at least basic sanitation from 73% to 86% in the same period;Brazil has a national system to finance water and sanitation infrastructure; [a high level of cost recovery compared to most other developing countries.
A high number of poor Brazilians live in urban slums (favela) and in rural areas without access to piped water or sanitation. Water is scarce in the northeast of Brazil. Water pollution is common, especially in the southeast of the country. Brazil has a low share of collected wastewater that is being treated (35% in 2000), and long-standing tensions between the federal, state and municipal governments about their respective roles in the sector.Water supply and sanitation in China
Water supply and sanitation in China is undergoing a massive transition while facing numerous challenges such as rapid urbanization, increasing economic inequality, and the supply of water to rural areas. Water scarcity and pollution also impact access to water.Progress has been made in the past decades, with increased access to services, increased municipal wastewater treatment, the creation of water and wastewater utilities that are legally and financially separated from local governments, and increasing cost recovery as part of the transformation of the Chinese economy to a more market-oriented system. The government quadrupled investments in the sector during the Eleventh Five-Year Plan (2006–10).
Nevertheless, much remains to be achieved. According to survey data analyzed by the Joint Monitoring Program for Water and Sanitation of WHO and UNICEF, about 100 million Chinese still did not have access to an improved water source in 2008, and about 460 million did not have access to improved sanitation. Progress in rural areas appears to lag behind what has been achieved in urban areas. According to data presented by the Joint Monitoring Program for Water Supply and Sanitation of WHO and UNICEF in 2015, about 36% of the rural population in China still did not have access to improved sanitation.Water supply and sanitation in Ethiopia
Access to water supply and sanitation in Ethiopia is amongst the lowest in Sub-Saharan Africa and the entire world. While access has increased substantially with funding from foreign aid, much still remains to be done to achieve the Millennium Development Goal of halving the share of people without access to water and sanitation by 2015, to improve sustainability and to improve service quality.
Some factors inhibiting the achievement of these goals are the limited capacity of water bureaus in the country's nine regions,two city administrations and water desks in the 550 districts of Ethiopia (woredas); insufficient cost recovery for proper operation and maintenance; and different policies and procedures used by various donors, notwithstanding the Paris Declaration on Aid Effectiveness.
In 2001 the government adopted a water and sanitation strategy that called for more decentralized decision-making; promoting the involvement of all stakeholders, including the private sector; increasing levels of cost recovery; as well as integrating water supply, sanitation and hygiene promotion activities. Implementation of the policy apparently is uneven.
In 2005 the government announced highly ambitious targets to increase coverage in its Plan for Accelerated Sustained Development and to End Poverty (PASDEP) for 2010. The investment needed to achieve the goal is about US$300 million per year, compared to actual investments of US$39 million in 2001–2002. In 2010 the government presented the equally ambitious Growth and Transformation Plan (GTP) 2011–2015, which aims at increasing drinking water coverage, based on the government's definition, from 68.5% to 98.5%. While donors have committed substantial funds to the sector, effectively spending the money and to ensure the proper operation and maintenance of infrastructure built with these funds remain a challenge.Water supply and sanitation in Ghana
The drinking water supply and sanitation sector in Ghana faces a number of challenges, including very limited access to sanitation, intermittent supply, high water losses and low water pressure. Since 1994, the sector has been gradually reformed through the creation of an autonomous regulatory agency, introduction of private sector participation, decentralization of the rural supply to 138 districts and increased community participation in the management of rural water systems.An international company has managed all urban water systems since 2006 under a 5-year management contract which expired after achieving only some of its objectives. The reforms also aim at increasing cost recovery and a modernization of the urban utility Ghana Water Company Limited (GWCL). Another problem which partly arose from the recent reforms is the existence of a multitude of institutions with overlapping responsibilities. The National Water Policy (NWP), launched at the beginning of 2008, seeks to introduce a comprehensive sector policy.Water supply and sanitation in India
Rapid improvements are being made in augmenting drinking water supply and sanitation in India, due to concerted efforts by the various levels of government and communities at improving coverage. The level of investment in water and sanitation, albeit low by international standards, has increased in size during the 2000s. For example, in 1980 rural sanitation coverage was estimated at 1% and reached 95% in 2018. Also, the share of Indians with access to improved sources of water has increased significantly from 72% in 1990 to 88% in 2008. At the same time, local government institutions in charge of operating and maintaining the infrastructure are seen as weak and lack the financial resources to carry out their functions. In addition, only two Indian cities have continuous water supply and according to an estimate from 2018 about 8% of Indians still lack access to improved sanitation facilities. A study by Water Aid estimated as many as 10 million Indians, or 5 percent of Indians living in urban areas, live without adequate sanitation. India comes in first place globally for having the greatest number of urban-dwelling inhabitants living without sanitation. India tops the urban sanitation crisis, has the largest amount of urban dwellers without sanitation, and the most open defecators(urban) with over 5 million people.A number of innovative approaches to improve water supply and sanitation have been tested in India, in particular in the early 2000s. These include demand-driven approaches in rural water supply since 1999, community-led total sanitation, a public-private partnerships to improve the continuity of urban water supply in Karnataka, and the use of micro credits for water supply and sanitation in order to improve access to water and sanitation.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 supply and sanitation in Russia
In Russia, approximately 70 per cent of drinking water comes from surface water and 30 per cent from groundwater. In 2004, water supply systems had a total capacity of 90 million cubic metres a day. The average residential water use was 248 litres per capita per day. One quarter of the world’s fresh surface and groundwater is located in Russia. The water utilities sector is one of the largest industries in Russia serving the entire Russian population.Water supply and sanitation in the Philippines
Water supply is the process of providing water in a systematic way through installed pumps and pipe lines. Before water is provided to a specific area, it undergoes a process called sanitation to ensure that the quality of water received is safe for human consumption. The Philippines’ water supply system dates back to 1946 after the country achieved its independence. Government agencies, local institutions, non-government organizations, and other corporations are primarily in charge in the operation and administration of water supply and sanitation in the country.Water supply network
A water supply system or water supply network is a system of engineered hydrologic and hydraulic components which provide water supply. A water supply system typically includes:
A drainage basin (see water purification - sources of drinking water).
A raw water collection point (above or below ground) where the water accumulates, such as a lake, a river, or groundwater from an underground aquifer. Raw water may be transferred using uncovered ground-level aqueducts, covered tunnels or underground water pipes to water purification facilities.
Water purification facilities. Treated water is transferred using water pipes (usually underground).
Water storage facilities such as reservoirs, water tanks, or water towers. Smaller water systems may store the water in cisterns or pressure vessels. Tall buildings may also need to store water locally in pressure vessels in order for the water to reach the upper floors.
Additional water pressurizing components such as pumping stations may need to be situated at the outlet of underground or above ground reservoirs or cisterns (if gravity flow is impractical).
A pipe network for distribution of water to the consumers (which may be private houses or industrial, commercial or institution establishments) and other usage points (such as fire hydrants).
Connections to the sewers (underground pipes, or aboveground ditches in some developing countries) are generally found downstream of the water consumers, but the sewer system is considered to be a separate system, rather than part of the water supply system.Water supply networks are often run by public utilities of the water industry.