Tap water

Tap water (running water, city water, municipal water, etc.) is potable water supplied to a tap (valve) inside the household or workplace. It is a principal component of "outdoor plumbing", which became available in suburban areas of the developed world during the last half of the 19th century, and common during the mid-20th century. The application of technologies involved in providing clean (potable) water to homes, businesses and public buildings is a major subfield of sanitary engineering. Calling potable water "tap water" distinguishes it from the other main types of potable water, such as water from rainwater-collecting cisterns, from village pumps (town pumps), or from streams, rivers, or lakes (whose potability varies). The availability of tap water has major public health disadvantages, since it typically vastly increases the risk to the public of contracting water-borne diseases. Providing tap water to large urban or suburban populations requires a complex and carefully designed system of collection, storage, treatment and distribution, and is commonly the responsibility of a government agency, often the same agency responsible for the removal and treatment of clean water. Specific chemical compounds are often taken out of tap water during the treatment process to adjust the pH or remove contaminants, as well as chlorine to kill biological toxins. Local geological conditions affecting groundwater 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. In the event of contamination deemed angerous to public health, government officials typically issue an advisory regarding water consumption. In the case of biological contamination, 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 a compound of fluoride is added to tap water in an effort to improve dental health among the public. In some communities "fluoridation" remains a controversial issue. (See water fluoridation controversy.) This supply may come from several possible sources. Municipal water supply Water wells 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, e.g., a stream or river. The water flow also allowed sending waste water away from the domiciles. Modern indoor plumbing delivers clean, safe, potable water to each service point in the distribution system. It is imperative that the clean water not be contaminated by the waste water (disposal) side of the process system. Historically, this contamination of drinking water has been the largest killer of humans.[1] [edit]Hot water supply Main article: Hot water system Domestic hot water is provided by means of water heater appliances, or through district 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.