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Tap water (also known as faucet water, running water, or municipal water) is
water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...
supplied through a tap, a water dispenser valve. In many countries, tap water usually has the quality of
drinking water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, ...
. Tap water is commonly used for drinking,
cooking Cooking, cookery, or culinary arts is the art, science and craft of using heat to prepare food for consumption. Cooking techniques and ingredients vary widely, from grilling food over an open fire to using electric stoves, to baking in vario ...
, washing, and
toilet flushing A flush toilet (also known as a flushing toilet, water closet (WC) – see also toilet names) is a toilet that disposes of human waste (principally urine and feces) by using the force of water to ''flush'' it through a drainpipe to another loca ...
. Indoor tap water is distributed through "indoor
plumbing Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, and other apparatuses to convey fluids. Heating and cooling (HVAC), waste removal, and potable water delive ...
", which has existed since
antiquity Antiquity or Antiquities may refer to: Historical objects or periods Artifacts *Antiquities, objects or artifacts surviving from ancient cultures Eras Any period before the European Middle Ages (5th to 15th centuries) but still within the histo ...
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 A developed country (or industrialized country, high-income country, more economically developed country (MEDC), advanced country) is a sovereign state that has a high quality of life, developed economy and advanced technological infrastruct ...
. Tap water became common in many regions during the 20th century, and is now lacking mainly among people in
poverty Poverty is the state of having few material possessions or little income. Poverty can have diverse
, especially in
developing countries A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...
. Governmental agencies commonly regulate tap water quality. Household water purification methods such as water filters,
boiling Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere. Th ...
, or
distillation Distillation, or classical distillation, is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a still. Dry distillation is the he ...
can be used to treat tap water's microbial contamination to improve its potability. The application of technologies (such as
water treatment Water treatment is any process that improves the quality of water to make it appropriate for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, inc ...
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).


Background

Providing tap water to large urban or
suburb A suburb (more broadly suburban area) is an area within a metropolitan area, which may include commercial and mixed-use, that is primarily a residential area. A suburb can exist either as part of a larger city/urban area or as a separ ...
an populations requires a complex and carefully designed system of collection, storage, treatment and
distribution Distribution may refer to: Mathematics * Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations *Probability distribution, the probability of a particular value or value range of a vari ...
, and is commonly the responsibility of a government agency. Publicly available treated water has historically been associated with major increases in
life expectancy Life expectancy is a statistical measure of the average time an organism is expected to live, based on the year of its birth, current age, and other demographic factors like sex. The most commonly used measure is life expectancy at birth ...
and improved
public health Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the det ...
.
Water disinfection Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for hu ...
can greatly reduce the risks of waterborne diseases such as
typhoid Typhoid fever, also known as typhoid, is a disease caused by ''Salmonella'' serotype Typhi bacteria. Symptoms vary from mild to severe, and usually begin six to 30 days after exposure. Often there is a gradual onset of a high fever over several d ...
and
cholera Cholera is an infection of the small intestine by some strains of the bacterium '' Vibrio cholerae''. Symptoms may range from none, to mild, to severe. The classic symptom is large amounts of watery diarrhea that lasts a few days. Vomiting an ...
. There is a great need around the world to disinfect drinking water. Chlorination is currently the most widely used water disinfection method, although chlorine compounds can react with substances in water and produce disinfection by-products (DBP) that pose problems to human health. Local geological conditions affecting
groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit ...
are determining factors for the presence of various metal ions, often rendering the water " soft" or " hard". Tap water remains susceptible to biological or chemical contamination. Water contamination remains a serious health issue around the world, and diseases resulted from consuming contaminated water cause the death of 1.6 million children each year. In the event of contamination deemed dangerous to public health, government officials typically issue an advisory regarding water consumption. In the case of
biological contamination A biological hazard, or biohazard, is a biological substance that poses a threat to the health of living organisms, primarily humans. This could include a sample of a microorganism, virus or toxin that can adversely affect human health. A ...
, residents are usually advised to boil their water before consumption or to use bottled water as an alternative. In the case of chemical contamination, residents may be advised to refrain from consuming tap water entirely until the matter is resolved. In many areas, low concentration of
fluoride Fluoride (). According to this source, is a possible pronunciation in British English. is an inorganic, monatomic anion of fluorine, with the chemical formula (also written ), whose salts are typically white or colorless. Fluoride salts ty ...
(< 1.0 ppm F) is intentionally added to tap water to improve
dental health Dental Public Health (DPH) is a para-clinical specialty of dentistry that deals with the prevention of oral disease and promotion of oral health. Dental public health is involved in the assessment of key dental health needs and coming up with effe ...
, although in some communities " fluoridation" remains a controversial issue. (See water fluoridation controversy). However, long-term consumption of water with high fluoride concentration (> 1.5 ppm F) can have serious undesirable consequences such as dental fluorosis, enamel mottle and skeletal fluorosis, bone deformities in children. Fluorosis severity depends on how much fluoride is present in the water, as well as people's diet and physical activity. Defluoridation methods include membrane-based methods, precipitation, absorption, and electrocoagulation.


Fixtures and appliances

Everything in a building that uses water falls under one of two categories; fixture or appliance. As the consumption points above perform their function, most produce waste/sewage components that will require removal by the waste/sewage side of the system. The minimum is an air gap. See cross connection control & backflow prevention for an overview of backflow prevention methods and devices currently in use, both through the use of mechanical and physical principles. Fixtures are devices that use water without an additional source of power.


Fittings and valves

Potable water supply systems are composed of pipes, fittings and
valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fitting ...
s.


Materials

The installation of water pipes can be done using the following plastic and metal materials:


Plastic

* polybutylene (PB) * high density cross-linked
polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging ( plastic bags, plastic films, geomembranes and containers including b ...
(PE-X) * block
copolymer In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are ...
of polypropylene (PP-B) * the polypropylene copolymer (PP-H) * random copolymer of polypropylene (random) (PP-R) * Layer: cross-linked polyethylene, aluminum, high-density polyethylene (PE-X / Al / PE-HD) * Layer: polyethylene crosslinked, aluminum, cross-linked polyethylene (PE-X / Al / PE-X) * Layer copolymer of a random polypropylene, aluminum, polypropylene random copolymer (PP-R / Al / PP-R) * polyvinyl chloride, chlorinated (PVC-C) * polyvinyl chloride - not softened(only cold water) (PVC-U)


Metals

*
carbon steel Carbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states: * no minimum content is specified or required for chromium, coba ...
, ordinary galvanized * corrosion resistant steel * Deoxidized High Phosphorus
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...
(Cu-DHP) *
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, ...
(no longer used for new installations due to its
toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subs ...
) Other materials, if the pipes made from them have been let into circulation and the widespread use in the construction of the water supply systems.


Lead pipes

For many centuries, water pipes were made of lead, because of its ease of processing and durability. The use of lead pipes was a cause of health problems due to ignorance of the dangers of lead on the human body, which causes miscarriages and high death rates of newborns. Lead pipes, which were installed mostly in the late 1800s in the US, are still common today, much of which are located in the Northeast and the Midwest. Their impact is relatively small due to the fouling of pipes and stone cessation of the evolution of lead in the water; however, lead pipes are still detrimental. Most of the lead pipes that exist today are being removed and replaced with the more common material, copper or some type of plastic. Remnants of pipes in some languages are the names of the experts involved in the execution, reparation, maintenance, and installation of water supply systems, which have been formed from the Latin word 'lead', English word 'plumber', French word, 'plombier'.


Potable water supply

Potable water is water that is drinkable and does not pose a risk to health. This supply may come from several possible sources. * Municipal water supply *
Water well A well is an excavation or structure created in the ground by digging, driving, or drilling to access liquid resources, usually water. The oldest and most common kind of well is a water well, to access groundwater in underground aquifers. T ...
s * Processed water from creeks, streams, rivers, lakes, rainwater, etc. Domestic water systems have been evolving since people first located their homes near a running water supply, such as a stream or river. The water flow also allowed sending wastewater away from the residences. Modern
plumbing Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, and other apparatuses to convey fluids. Heating and cooling (HVAC), waste removal, and potable water delive ...
delivers clean, safe, and potable water to each service point in
water distribution system A water distribution system is a part of water supply network with components that carry potable water from a centralized treatment plant or wells to consumers to satisfy residential, commercial, industrial and fire fighting requirements. Defin ...
, including taps. It is important that the clean water not be contaminated by the wastewater (disposal) side of the process system. Historically, this contamination of drinking water has been one of the largest killers of humans. Most of the mandates for enforcing drinking water quality standards are not for the distribution system, but for the treatment plant. Even though the water distribution system is supposed to deliver the treated water to the consumers' taps without water quality degradation, complicated physical, chemical, and biological factors within the system can cause contamination of tap water. There is a huge gap regarding the potable water supply between the developed and developing world. In general, Africa, especially Sub-Saharan Africa, has the poorest water supply system in the world because of the insufficient access to the system and the low quality of the water in the region, while
Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bot ...
has the best tap water quality in the world according to a reports by
UNICEF UNICEF (), originally called the United Nations International Children's Emergency Fund in full, now officially United Nations Children's Fund, is an agency of the United Nations responsible for providing humanitarian and developmental aid to c ...
and
UNESCO The United Nations Educational, Scientific and Cultural Organization is a List of specialized agencies of the United Nations, specialized agency of the United Nations (UN) aimed at promoting world peace and security through international coope ...
. Tap water can sometimes appear cloudy and is often mistaken for mineral impurities in the water. It is usually caused by air bubbles coming out of solution due to change in temperature or pressure. Because cold water holds more air than warm water, small bubbles will appear in water. It has a high dissolved gas content that is heated or depressurized, which reduces how much dissolved gas the water can hold. The harmless cloudiness of the water disappears quickly as the gas is released from the water.


Hot water supply

Domestic hot water is provided by means of water heater appliances, or through
district heating District heating (also known as heat networks or teleheating) is a system for distributing heat generated in a centralized location through a system of insulated pipes for residential and commercial heating requirements such as space heating ...
. The hot water from these units is then piped to the various fixtures and appliances that require hot water, such as lavatories, sinks, bathtubs, showers, washing machines, and dishwashers.


Water flow reduction

Water flow through a tap can be reduced by inexpensive small plastic flow reducers. These restrict flow between 15 and 50%, aiding
water conservation Water conservation includes all the policies, strategies and activities to sustainably manage the natural resource of fresh water, to protect the hydrosphere, and to meet the current and future human demand (thus avoiding water scarcity). Popula ...
and reducing the burden on both
water supply Water supply is the provision of water by public utilities, commercial organisations, community endeavors or by individuals, usually via a system of pumps and pipes. Public water supply systems are crucial to properly functioning societies. Th ...
and treatment facilities.


Wastewater

Wastewater from various appliances, fixtures, and taps is transferred to the waste and sewage removal system via the sewage drain system to treatment plants. This system consists of larger diameter piping, water traps, and ventilation to prevent toxic gases from entering the living space.


Comparison to bottled water


United States

Contaminant levels found in tap water vary between
household A household consists of two or more persons who live in the same dwelling. It may be of a single family or another type of person group. The household is the basic unit of analysis in many social, microeconomic and government models, and is i ...
s and plumbing systems. While the majority of US households have access to high-quality tap water, demand for bottled water increases. In 2002, the Gallup Public Opinion Poll revealed that the possible health risk associated with tap water consumption is one of the main reasons that cause American consumers to prefer bottled water over tap water. The trust level towards tap water depends on various criteria, including the existing governmental regulations towards the water quality and their appliance. In 1993, the cryptosporidium outbreak in
Milwaukee, Wisconsin Milwaukee ( ), officially the City of Milwaukee, is both the most populous and most densely populated city in the U.S. state of Wisconsin and the county seat of Milwaukee County. With a population of 577,222 at the 2020 census, Milwaukee i ...
, led to a massive hospitalization of more than 400,000 residents and was considered the largest in US history. Severe violations of tap water standards influence the decrease in public trust. The difference in water quality between bottled and tap water is debatable. In 1999, the Natural Resources Defense Council (NRDC) released controversial findings from a 4-year study on bottled water. The study claimed that one-third of the tested waters were contaminated with synthetic organic chemicals,
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...
, and
arsenic Arsenic is a chemical element with the 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, b ...
. At least one sample exceeded state guidelines for contamination levels in bottled water. In the United States, some municipalities make an effort to use tap water over bottled water on governmental properties and events. Voters in Washington State repealed a bottled water tax via citizen initiative.


Regulation and compliance


United States

The US Environmental Protection Agency (EPA) regulates the allowable levels of some contaminants in
public water system Public water system is a regulatory term used in the United States and Canada, referring to certain utilities and organizations providing drinking water. United States The US Safe Drinking Water Act and derivative legislation define "public wate ...
s. There may also be numerous contaminants in tap water that are not regulated by EPA and yet potentially harmful to human health. Community water systems—those systems that serve the same people throughout the year—must provide an annual " Consumer Confidence Report" to customers. The report identifies contaminants, if any, in the water system and explains the potential health impacts. After the Flint lead crisis (2014), researchers have paid special attention in studying quality trends in drinking water all across the USA. Unsafe level of lead were found in tap water in different cities, such as Sebring, Ohio in August 2015, and Washington, DC, in 2001. Several studies show that a Safe Drinking Water Act (SDWA) health violation occurs in around 7-8% of community water system (CWS) in an average year. Around 16 million cases of acute gastroenteritis occur each year in the US, due to the existence of contaminants in drinking water. Before a water supply system is constructed or modified, the designer and contractor are required to consult the local plumbing code and obtain a building permit prior to construction.''International Plumbing Code'', ICC Replacing an existing water heater may require a permit and inspection of the work. The US national standard for potable water piping guidelines is NSF/ANSI 61 certified materials. NSF/ANSI also sets standards for certifying polytanks, though the
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...
(FDA) approves the materials.


Japan

To improve water quality, Japan’s Ministry of Health revised its water quality standards, which were implemented in April 2004. Numerous professionals developed the drinking water standards. They also determined ways to manage the high quality water system. In 2008, improved regulations were conducted to improve the water quality and reduce the risk of water contamination.


See also

* * * * * * * * * * * * * *


References

*
ASTM ASTM International, formerly known as American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, an ...
B75-02 Specification for Seamless Copper Tube *
ASTM ASTM International, formerly known as American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, an ...
B42-02e1 Standard Specification for Seamless Copper Pipe, Standard Sizes *
ASTM ASTM International, formerly known as American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, an ...
B88-03 Standard Specification for Seamless Copper Water Tube * AWWA Research Foundation, Residential End Uses of Water, , 1999


External links


The Water Information Center
- An online resource for public water system basics and water management issues from the National Academy of Sciences.

- One-stop resource for information on public water systems supplying tap water including information on drinking water, fluoridation, water testing, water-related diseases and contaminants, etc., plus links to EPA, WHO, and other resources.
the International Code Councilthe American Society for Testing and Materialsthe National Ground Water AssociationThe Copper Development Association
��Copper Pipe weights and max PSI {{DEFAULTSORT:Tap Water Water Drinking water Water pollution Water supply infrastructure