Tap water (also known asrunning water,piped water ormunicipal water) iswater supplied through atap, a water dispenser valve. In many countries, tap water usually has the quality ofdrinking water. Tap water is commonly used fordrinking,cooking, andwashing. Indoor tap water is distributed through indoorplumbing, which has been around sinceantiquity 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 nowdeveloped countries. Tap water became common in many regions during the 20th century, and is now lacking mainly among people inpoverty, especially indeveloping countries.
Governmental agencies commonly regulatetap water quality. Calling a water supply "tap water" distinguishes it from the other main types of fresh water which may be available; these include water fromrainwater-collectingcisterns, water fromvillage pumps or town pumps, water fromwells, or water carried from streams, rivers, or lakes (whose potability may vary).
A synonym fortap water ispiped water, a term used by theJoint Monitoring Programme (JMP) for Water Supply and Sanitation byWHO andUNICEF to describe the situation foraccess to drinking water indeveloping countries.[2] Piped water is not necessarily of drinking water quality but does count as an "improved water source" in the logic ofSustainable Development Goal 6. Other improved water sources include boreholes, protected dug wells or springs, rainwater, andbottled or water delivered by tanker.[2]: 12
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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. Seecross 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.[citation needed]
Fixtures are devices that use water without an additional source of power.
Potable water supply systems are composed ofpipes,fittings, andvalves.
Water flow through a tap can be reduced by inexpensive small plastic flow reducers. These restrict flow between 15 and 50%, aidingwater conservation and reducing the burden on bothwater supply andtreatment facilities.
The installation ofwater pipes can be done using the following plastic[3] and metal[3] materials:
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.
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.[4] 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.
Modernplumbing delivers clean, safe, and potable water to each service point inwater distribution system, including taps.[5] 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.[6]
Most of the mandates for enforcingdrinking 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.[5]
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.[7]
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Water supply is the provision ofwater bypublic utilities, commercial organisations, community endeavors or by individuals, usually via a system of pumps andpipes. Public water supply systems are crucial to properly functioning societies. These systems are what supply drinking water to populations around the globe.[8] Aspects of service quality include continuity of supply,water quality and water pressure. The institutional responsibility for water supply is arranged differently in different countries and regions (urban versus rural). It usually includes issues surrounding policy and regulation, service provision andstandardization.
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). Almost all service providers in the world charge tariffs to recover part of their costs. | The examples and perspective in this sectionmay not represent aworldwide view of the subject. You mayimprove this section, discuss the issue on thetalk page, or create a new section, as appropriate.(October 2023) (Learn how and when to remove this message) |
Bottled water may have reduced amounts of copper, lead, and other metal contaminants since it does not run through the plumbing pipes where tap water is exposed to metal corrosion; however, this varies by the household and plumbing system.[9]
In much of the developed world,chlorine often is added as a disinfectant to tap water. If the water contains organic matter, this may produce other byproducts in the water such astrihalomethanes andhaloacetic acids, which has shown to increase the risk of cancer.[10] The level of residual chlorine found at around 0.0002 g per litre, which is too small to cause any health problems directly.[9] The chlorine concentration recommended byWorld Health Organization is between 0.0002 and 0.0005 g/L.[11]
The documentaryTapped argues against the bottled water industry, asserting that tap water is healthier, more environmentally sustainable, and more ecologically sound than bottled water. The film focuses on the bottled water industry in the United States. The film has received largely positive reviews, and has spawned college campus groups such asBeyond the Bottle. Yet, as many people remain generally unaware of the negative health and environmental impacts associated with bottled water, recent research inenvironmental psychology has started to investigate how to reduce the public's consumption of bottled water.[12][13][14]Contaminant levels found in tap water vary betweenhouseholds andplumbing systems. While the majority of US households have access to high-quality tap water, demand forbottled water increases.[15] In 2002, theGallup 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.[16]
The trust level towards tap water depends on various criteria, including the existing governmental regulations towards the water quality and their appliance. In 1993,a cryptosporidiosis outbreak in Milwaukee, Wisconsin led to a massive hospitalization of more than 400,000 residents and was considered the largest in US history.[17] Severe violations of tap water standards influence the decrease in public trust.[18]
The difference in water quality between bottled and tap water is debatable. In 1999, theNatural 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 withsynthetic organic chemicals,bacteria, andarsenic. At least one sample exceeded state guidelines for contamination levels in bottled water.[19]
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.[20][21]
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