Swimming pool
Overview
A swimming pool, swimming bath, wading pool, or simply a pool, is a container filled with water intended for swimming or water-based recreation
Recreation
Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or pleasure and are considered to be "fun"...

. There are many standard sizes; the largest is the Olympic-size swimming pool. A pool can be built either above or in the ground, and from materials such as concrete (also known as gunite), metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

, plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

 or fiberglass
Fiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...

.

Pools that may be used by many people or by the general public are called public, while pools used exclusively by a few people or in a home are called private.
Encyclopedia
A swimming pool, swimming bath, wading pool, or simply a pool, is a container filled with water intended for swimming or water-based recreation
Recreation
Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or pleasure and are considered to be "fun"...

. There are many standard sizes; the largest is the Olympic-size swimming pool. A pool can be built either above or in the ground, and from materials such as concrete (also known as gunite), metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

, plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

 or fiberglass
Fiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...

.

Pools that may be used by many people or by the general public are called public, while pools used exclusively by a few people or in a home are called private. Many health club
Health club
A health club is a place which houses exercise equipment for the purpose of physical exercise.-Main workout area:...

s, fitness centers and private clubs have public pools used mostly for exercise. Many hotel
Hotel
A hotel is an establishment that provides paid lodging on a short-term basis. The provision of basic accommodation, in times past, consisting only of a room with a bed, a cupboard, a small table and a washstand has largely been replaced by rooms with modern facilities, including en-suite bathrooms...

s and massage parlor
Massage parlor
A massage parlor is a business where customers can receive a massage. Sometimes the term is synonymous with brothel as the term "massage" may be used as a euphemism for paid sexual favours....

s have public pools for relaxation. Hot tub
Hot tub
A hot tub is a large tub or small pool full of heated water and used for soaking, relaxation, massage, or hydrotherapy. In most cases, they have jets for massage purposes. Hot tubs are usually located outdoors, and are often sheltered for protection from the elements, as well as for privacy....

s and spa
Spa
The term spa is associated with water treatment which is also known as balneotherapy. Spa towns or spa resorts typically offer various health treatments. The belief in the curative powers of mineral waters goes back to prehistoric times. Such practices have been popular worldwide, but are...

s are pools with hot water, used for relaxation or therapy, and are common in homes, hotels, clubs and massage parlors. Swimming pools are also used for diving
Diving
Diving is the sport of jumping or falling into water from a platform or springboard, sometimes while performing acrobatics. Diving is an internationally-recognized sport that is part of the Olympic Games. In addition, unstructured and non-competitive diving is a recreational pastime.Diving is one...

 and other water sports, as well as for the training of lifeguard
Lifeguard
A lifeguard supervises the safety and rescue of swimmers, surfers, and other water sports participants such as in a swimming pool, water park, or beach. Lifeguards are strong swimmers and trained in first aid, certified in water rescue using a variety of aids and equipment depending on...

s and astronaut
Astronaut
An astronaut or cosmonaut is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft....

s.

Chemical disinfectants such as chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

, bromine
Bromine
Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...

 or mineral sanitizers, and additional filters are often used in swimming pools to prevent growth and spread of bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

, virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

es, algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

 and insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

 larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e. Alternatively, pools can be made without chemical disinfectants by using a biofilter with additional carbon filters and UV
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

 disinfection. In both cases, pools need to be fitted with an adequate flow rate.

History

The "Great Bath
Great Bath, Mohenjo-daro
The Great Bath is one of the best known structures among the ruins of the ancient Indus Valley Civilization at Mohenjo-daro in Sindh, Pakistan. It is located in the well-preserved northern part of Mohenjo-daro's western mound, which is also known as the "Mound of the Great Bath" or the...

" at the site of Mohenjo-Daro
Mohenjo-daro
Mohenjo-daro is an archeological site situated in what is now the province of Sindh, Pakistan. Built around 2600 BC, it was one of the largest settlements of the ancient Indus Valley Civilization, and one of the world's earliest major urban settlements, existing at the same time as the...

 in modern-day Pakistan was most likely the first swimming pool, dug during the 3rd millennium BC. This pool is 12 by 7 meters, is lined with bricks and was covered with a tar-based sealant.

Ancient Greeks
Ancient Greece
Ancient Greece is a civilization belonging to a period of Greek history that lasted from the Archaic period of the 8th to 6th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and the Byzantine era. Included in Ancient Greece is the...

 and Romans
Ancient Rome
Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....

 built artificial pools for athletic training in the palaestra
Palaestra
The palaestra was the ancient Greek wrestling school. The events that did not require a lot of space, such as boxing and wrestling, were practised there...

s, for nautical games and for military exercises. Roman emperors had private swimming pools in which fish were also kept, hence one of the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 words for a pool, piscina. The first heated swimming pool was built by Gaius Maecenas
Gaius Maecenas
Gaius Cilnius Maecenas was a confidant and political advisor to Octavian as well as an important patron for the new generation of Augustan poets...

 of Rome in the first century BC. Gaius Maecenas was a rich Roman lord and considered one of the first patrons of arts.

Ancient Sinhalese
Sinhalese people
The Sinhalese are an Indo-Aryan ethnic group,forming the majority of Sri Lanka,constituting 74% of the Sri Lankan population.They number approximately 15 million worldwide.The Sinhalese identity is based on language, heritage and religion. The Sinhalese speak Sinhala, an Indo-Aryan language and the...

 built pairs of pools called "Kuttam Pokuna
Kuttam Pokuna
One of the best specimen of bathing tanks or pools in ancient Sri Lanka is the pair of pools known as Kuttam Pokuna . The said pair of pools were built by the Sinhalese in the ancient kingdom of Anuradhapura...

" in the kingdom of Anuradhapura
Anuradhapura
Anuradhapura, , is one of the ancient capitals of Sri Lanka, famous for its well-preserved ruins of ancient Lankan civilization.The city, now a UNESCO World Heritage Site, lies 205 km north of the current capital Colombo in Sri Lanka's North Central Province, on the banks of the historic...

, Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

 in the 4th century BC. They were decorated with flights of steps, punkalas or pots of abundance and scroll design.
Swimming pools became popular in Britain in the mid 19th century. By 1837, six indoor pools with diving boards were built in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

. The oldest surviving Swimming Club in the World is believed to be Maidstone Swimming Club in Maidstone
Maidstone
Maidstone is the county town of Kent, England, south-east of London. The River Medway runs through the centre of the town linking Maidstone to Rochester and the Thames Estuary. Historically, the river was a source and route for much of the town's trade. Maidstone was the centre of the agricultural...

, Kent
Kent
Kent is a county in southeast England, and is one of the home counties. It borders East Sussex, Surrey and Greater London and has a defined boundary with Essex in the middle of the Thames Estuary. The ceremonial county boundaries of Kent include the shire county of Kent and the unitary borough of...

, England. It was formed in 1844 when there was concern over drownings in the River Medway
River Medway
The River Medway, which is almost entirely in Kent, England, flows for from just inside the West Sussex border to the point where it enters the Thames Estuary....

. Rescuers would often die in the water because they could usually not swim to safety themselves. The club used to swim in the river and would hold races, diving competitions and water polo
Water polo
Water polo is a team water sport. The playing team consists of six field players and one goalkeeper. The winner of the game is the team that scores more goals. Game play involves swimming, treading water , players passing the ball while being defended by opponents, and scoring by throwing into a...

 matches in the Medway. The South East Gazette July 1844 reported an aquatic breakfast party. Coffee and biscuits were served on a floating raft in the river, the coffee was kept hot over a fire and club members had to tread water and drink coffee at the same time. The last swimmers managed to overturn the raft to the amusement of the 150 spectators!

After the modern Olympic Games
Olympic Games
The Olympic Games is a major international event featuring summer and winter sports, in which thousands of athletes participate in a variety of competitions. The Olympic Games have come to be regarded as the world’s foremost sports competition where more than 200 nations participate...

 began in 1896 and included swimming races, the popularity of swimming pools began to spread. In 1839, Oxford
Oxford
The city of Oxford is the county town of Oxfordshire, England. The city, made prominent by its medieval university, has a population of just under 165,000, with 153,900 living within the district boundary. It lies about 50 miles north-west of London. The rivers Cherwell and Thames run through...

 had its first major public indoor pool at Temple Cowley, and swimming began to take off. The Amateur Swimming Association was founded in 1869 in England, and the Oxford Swimming Club in 1909 with its home at Temple Cowley Pool. The presence of indoor baths in the cobbled area of Merton Street
Merton Street
Merton Street is a historic and picturesque cobbled lane in central Oxford, England. It joins the High Street at its northeastern end, between the Ruskin School of Drawing & Fine Art and the Eastgate Hotel at the historic east gate of the city...

, London may have persuaded the less hardy of the aquatic brigade to join. So, bathers gradually became swimmers, and bathing pools swimming pools.

In the USA, the Racquet Club of Philadelphia
Racquet Club of Philadelphia
The Racquet Club of Philadelphia is a private social club and athletic club in Philadelphia, Pennsylvania. It has facilities for squash, real tennis, and racquets....

 clubhouse (1907) boasts one of the world's first modern above-ground swimming pools. The first swimming pool to go to sea on an ocean liner was installed on the White Star Line
White Star Line
The Oceanic Steam Navigation Company or White Star Line of Boston Packets, more commonly known as the White Star Line, was a prominent British shipping company, today most famous for its ill-fated vessel, the RMS Titanic, and the World War I loss of Titanics sister ship Britannic...

's Adriatic
RMS Adriatic (1907)
RMS Adriatic was an ocean liner of the White Star Line. She was the fourth of a quartet of ships measuring over 20,000 tons, dubbed The Big Four, the ship was the only one of the four which was never the world's largest ship however, she was the fastest of the Big Four...

 in 1907.

Interest in competitive swimming grew following World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. Standards improved and training became essential. Home swimming pools became popular in the United States after World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 and the publicity given to swimming sports by Hollywood films like Esther Williams
Esther Williams
Esther Jane Williams is a retired American competitive swimmer and MGM movie star.Williams set multiple national and regional swimming records in her late teens as part of the Los Angeles Athletic Club swim team...

 Million Dollar Mermaid made a home pool a desirable status symbol. More than fifty years later, the home or residential swimming pool is ubiquitous and even small nations enjoy a thriving swimming pool industry (e.g. New Zealand pop. 4,116,900 [Source NZ Census 7 March 2006] - holds the record in pools per capita with 65,000 home swimming pools and 125,000 spa pools).
A two-storey, white concrete swimming pool building composed of horizontal cubic volumes built in 1959 at the Royal Roads Military College
Royal Roads Military College
Royal Roads Military College was a Canadian military college located in Hatley Park, Colwood, British Columbia near Victoria, British Columbia, Canada. The facility is currently being used as the campus for Royal Roads University, a public university that offers applied and professional academic...

 is on the Registry of Historic Places of Canada.

Swimming pool records

According to the Guinness World Records
Guinness World Records
Guinness World Records, known until 2000 as The Guinness Book of Records , is a reference book published annually, containing a collection of world records, both human achievements and the extremes of the natural world...

, the largest swimming pool in the world is San Alfonso del Mar
San Alfonso del Mar
San Alfonso del Mar is a private resort located in Algarrobo, Chile, about west of the capital Santiago. It is notable for having the Guinness world record for the largest and deepest swimming pool in the world. It has been attracting tourists since it opened in December 2006.-Pool and resort:San...

 Seawater pool in Algarrobo
Algarrobo, Chile
Algarrobo is a Chilean city and commune in San Antonio Province, Valparaíso Region. Located on the country's central coast, it is a popular summer resort for the population of Santiago...

, Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

. It is 1013 m (3,323.5 ft) long and has an area of 8 ha (20 acres). At its deepest, it is 35 m (114.8 ft) deep. It was completed in December 2006.

The largest indoor wave pool
Wave pool
A wave pool is a swimming pool in which there are artificially generated, reasonably large waves, similar to the ocean's. Wave pools are often a major feature of water parks...

 in North America is at the West Edmonton Mall
West Edmonton Mall
West Edmonton Mall , located in Edmonton, Alberta, Canada, is the largest shopping mall in North America and the fifth largest in the world. The mall was founded by the Ghermezian brothers, who emigrated from Iran in 1959. It was the world's largest mall until 2004.West Edmonton Mall covers a gross...

 and the largest indoor pool is at the Neutral Buoyancy Lab in the Sonny Carter Training Facility at NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 JSC
Lyndon B. Johnson Space Center
The Lyndon B. Johnson Space Center is the National Aeronautics and Space Administration's center for human spaceflight training, research and flight control. The center consists of a complex of 100 buildings constructed on 1,620 acres in Houston, Texas, USA...

 in Houston.

The recreational diving center Nemo 33
Nemo 33
Nemo 33 is the deepest indoor swimming pool in the world. The pool is located in Brussels, Belgium. Its maximum depth is . It contains 2.5 million liters of non-chlorinated, highly filtered spring water maintained at 30 °C and holds several simulated underwater caves at the depth level...

 near Brussels
Brussels
Brussels , officially the Brussels Region or Brussels-Capital Region , is the capital of Belgium and the de facto capital of the European Union...

, Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...

 is home to the world's deepest indoor pool. The pool has two large flat-bottomed areas at depth levels of 5 m (16.4 ft) and 10 m (32.8 ft), and a large circular pit descending to a depth of 33 m (108.3 ft).

The Fleishhacker Pool
Fleishhacker Pool
Fleishhacker Pool was a public saltwater swimming pool located in the southwest corner of San Francisco, California next to the zoo for 47 years. It was the largest swimming pool in the United States and it was said that it could be seen from space....

 in San Francisco, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 was the largest swimming pool in the United States. Opened on 23 April 1925, it measured 1000 by and was so large that the lifeguards required kayak
Kayak
A kayak is a small, relatively narrow, human-powered boat primarily designed to be manually propelled by means of a double blade paddle.The traditional kayak has a covered deck and one or more cockpits, each seating one paddler...

s for patrol. It was closed in 1971 due to low patronage.

In Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, the largest swimming pool opened on 6 August 1965 in Fürstenfeld
Fürstenfeld
Fürstenfeld is a town and a district in southeastern Austria. It is situated within the Austrian federal state of StyriaAccording to the 2005 census, Fürstenfeld has 5,986 citizens within its communal area, the larger urban area of Fürstenfeld includes approximately 20% more citizens.Fürstenfeld...

 (Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...

), providing a water area of 23000 m2.

One of the largest swimming pools ever built was reputedly in Moscow
Moscow
Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent...

 after the Palace of Soviets
Palace of Soviets
The Palace of the Soviets was a project to construct an administrative center and a congress hall in Moscow, Russia, near the Kremlin, on the site of the demolished Cathedral of Christ the Saviour...

 remained uncompleted. The foundations were converted into the Moskva Pool
Moskva Pool
The Moskva Pool was, for a time, the world's largest open air swimming pool.It was built in Moscow in 1958 on the foundation of the abandoned Palace of Soviets, to the designs of prominent Moscow architect Dmitry Chechulin...

 open air swimming pool after the process of de-Stalinisation. After the fall of communism
Communism
Communism is a social, political and economic ideology that aims at the establishment of a classless, moneyless, revolutionary and stateless socialist society structured upon common ownership of the means of production...

, Christ the Saviour Cathedral was re-built (it had originally been on the site) between 1995 and 2000.

The highest swimming pool is probably located in Yangbajain (Tibet, China). This resort is located at 4200 m AMSL and has two indoor swimming pools and one outdoor swimming pool, all filled with water from hot spring
Hot spring
A hot spring is a spring that is produced by the emergence of geothermally heated groundwater from the Earth's crust. There are geothermal hot springs in many locations all over the crust of the earth.-Definitions:...

s.

Dimensions

See: #Competition pools (below)

Length:
Most pools in the world are measured in metres, but in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 pools are almost always measured in feet and yard
Yard
A yard is a unit of length in several different systems including English units, Imperial units and United States customary units. It is equal to 3 feet or 36 inches...

s. In the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 most pools are in metres, but older pools measured in yards still exist. In the US, pools tend to either be 25 yards (SCY-short course
Short course
In Swimming, the term Short Course is used to identify a pool that is 25 metres in length. The term is also often included in meet names when conducted in a short course pool...

 yards), 25 metres (SCM-short course metres) or 50 metres (long course). US high schools and the NCAA conduct short course (25 yards) competition. There also exist many pools 33⅓ m long, so that 3 lengths = 100 m. This pool dimension is commonly used to accommodate water polo
Water polo
Water polo is a team water sport. The playing team consists of six field players and one goalkeeper. The winner of the game is the team that scores more goals. Game play involves swimming, treading water , players passing the ball while being defended by opponents, and scoring by throwing into a...

.

USA Swimming
USA Swimming
USA Swimming is the national governing body for competitive swimming in the United States. It is charged with selecting the United States Olympic Swimming team and any other teams which officially represent the United States, as well as the overall organization and operation of the sport within the...

 (USA-S) swims in both metric and non-metric pools. However, the international standard is metres, and world records are only recognized when swum in 50 m pools (or 25 m for short course). In general, the shorter the pool, the faster the time for the same distance, since the swimmer gains speed from pushing off the wall after each turn at the end of the pool.

Width:
Most European pools are between 10 m and 50 m wide.

Depth:
The depth of a swimming pool depends on the purpose of the pool, and whether it is open to the public or strictly for private use. If it is a private casual, relaxing pool, it may go from 1 to 2 m (3.3 to 6.6 ft) deep. If it is a public pool designed for diving, it may slope from 3 to 5.5 m (9.8 to 18 ft) in the deep end. A children's play pool may be from 0.3 to 1.2 m (0.984251968503937 to 3.9 ft) deep. Most public pools have differing depths to accommodate different swimmer requirements. In many jurisdictions, it is a requirement to show the water depth with clearly marked depths affixed to the pool walls.

Private pools

Private pools are usually smaller than public pools, on average 12 by 24 ft (3.7 by 7.3 m) to 20 by 40 ft (6.1 by 12.2 m) whereas public pools usually start at 80 ft (24.4 m). Home pools can be permanently built-in, or be assembled above ground and disassembled after summer. Privately owned outdoor pools in backyards or gardens started to proliferate in the 1950s in regions with warm summer climates, particularly in the United States.
Private pools are increasingly a feature of homes in greater latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

s. For example, in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

 many larger homes are now refurbished with indoor pools, usually in the basement
Basement
__FORCETOC__A basement is one or more floors of a building that are either completely or partially below the ground floor. Basements are typically used as a utility space for a building where such items as the furnace, water heater, breaker panel or fuse box, car park, and air-conditioning system...

 or in a conservatory.

Construction methods for private pools vary greatly. The main types of in-ground pools are concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

, vinyl
Vinyl
A vinyl compound is any organic compound that contains a vinyl group ,which are derivatives of ethene, CH2=CH2, with one hydrogen atom replaced with some other group...

 liner, and one-piece fiberglass
Fiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...

. Above-ground pools (also called "on-ground pools") are cheaper to build.

Inexpensive temporary Polyvinyl chloride
Polyvinyl chloride
Polyvinyl chloride, commonly abbreviated PVC, is a thermoplastic polymer. It is a vinyl polymer constructed of repeating vinyl groups having one hydrogen replaced by chloride. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene. PVC is widely used in...

 pools can be bought in supermarket
Supermarket
A supermarket, a form of grocery store, is a self-service store offering a wide variety of food and household merchandise, organized into departments...

s and taken down after summer. They are used mostly outdoors in yards, are typically shallow, and often their sides are inflated with air to stay rigid. When finished, the water and air can be let out and this type of pool can be folded up for convenient storage. They are regarded in the swimming pool industry as "splasher" pools intended for cooling off and amusing toddlers and children, not for swimming, hence the alternate name of "kiddie" pools.

Toy
Toy
A toy is any object that can be used for play. Toys are associated commonly with children and pets. Playing with toys is often thought to be an enjoyable means of training the young for life in human society. Different materials are used to make toys enjoyable and cuddly to both young and old...

s are available for children and other people to play with in pool water. They are often blown up with air so they are soft but still reasonably rugged, and can float in water.

Many countries now have strict pool fencing
Pool fence
A pool fence is a type of fence placed around backyard swimming pools, commonly to improve pool safety and to help prevent small children from accidentally falling into the pool and drowning.-Various materials:...

 laws for private swimming pools, which require pool areas to be isolated so that unauthorized children younger than six years cannot enter. Many countries require a similar level of protection for the children residing in or visiting the house, although many pool owners prefer the visual aspect of the pool in close proximity to their living areas, and will not provide this level of protection. There is no consensus between states or countries on the requirements to fence private swimming pools, and in many places they are not required at all, particularly in rural settings.

Public pools

Public pools are often found as part of a larger leisure centre or recreational complex. These centres often have more than one pool, such as an indoor heated pool, an outdoor (chlorinated
Chlorination
Chlorination is the process of adding the element chlorine to water as a method of water purification to make it fit for human consumption as drinking water...

 or saltwater
Saltwater pool
Salt water chlorination is a process that uses dissolved salt as a store for the chlorination system. The chlorinator uses electrolysis to break down the salt . The resulting chemical reaction eventually produces hypochlorous acid , and sodium hypochlorite , which are the sanitizing agents already...

) which may be heated or unheated pool, a shallower children's pool, and a paddling pool for toddler
Toddler
A toddler is a young child, usually defined as being between the ages of one and three. Registered nurse, midwife and author, Robin Barker, states 'Any time from eight months onwards your baby will begin to realise he is a separate person from you...

s and infant
Infant
A newborn or baby is the very young offspring of a human or other mammal. A newborn is an infant who is within hours, days, or up to a few weeks from birth. In medical contexts, newborn or neonate refers to an infant in the first 28 days after birth...

s. There may also be a sauna
Sauna
A sauna is a small room or house designed as a place to experience dry or wet heat sessions, or an establishment with one or more of these and auxiliary facilities....

 and one or more hot tub
Hot tub
A hot tub is a large tub or small pool full of heated water and used for soaking, relaxation, massage, or hydrotherapy. In most cases, they have jets for massage purposes. Hot tubs are usually located outdoors, and are often sheltered for protection from the elements, as well as for privacy....

s or spa
Spa
The term spa is associated with water treatment which is also known as balneotherapy. Spa towns or spa resorts typically offer various health treatments. The belief in the curative powers of mineral waters goes back to prehistoric times. Such practices have been popular worldwide, but are...

 pools ("jacuzzi
Jacuzzi
Jacuzzi is a company that produces whirlpool bathtubs and spas. Its first product was a bath with massaging jets. The term "jacuzzi" is now often used generically to refer to any bathtub with massaging jets.-History:...

s").

Public pools may occasionally belong to a hotel
Hotel
A hotel is an establishment that provides paid lodging on a short-term basis. The provision of basic accommodation, in times past, consisting only of a room with a bed, a cupboard, a small table and a washstand has largely been replaced by rooms with modern facilities, including en-suite bathrooms...

 or holiday resort, as an amenity for the recreation of their guests. If a pool is in a separate building, the building may be called a "natatorium". The building sometimes also has facilities for related activities, such as a diving tank. Larger pools sometimes have a diving board
Springboard
A springboard or diving board is used for diving and is a board that is itself a spring, i.e. a linear flex-spring, of the cantilever type....

 affixed at one edge above the water.

Many public swimming pools are rectangle
Rectangle
In Euclidean plane geometry, a rectangle is any quadrilateral with four right angles. The term "oblong" is occasionally used to refer to a non-square rectangle...

s 25 m or 50 m long, but may be any size and shape desired. There are also elaborate pools with artificial waterfall
Waterfall
A waterfall is a place where flowing water rapidly drops in elevation as it flows over a steep region or a cliff.-Formation:Waterfalls are commonly formed when a river is young. At these times the channel is often narrow and deep. When the river courses over resistant bedrock, erosion happens...

s, fountain
Fountain
A fountain is a piece of architecture which pours water into a basin or jets it into the air either to supply drinking water or for decorative or dramatic effect....

s, splash pad
Splash pad
A splash pad is an area for water play that has no standing water. This is said to eliminate the need for lifeguards or other supervision, as there is practically no risk of drowning. Splash pads have been around in the commercial industry for decades....

s, wave machines, varying depths of water, bridges, and island bars.

There are often lockers for clothing and other belongings. The lockers often require a coin to be inserted as deposit or payment. There are usually showers - sometimes mandatory - before and/or after swimming. There are often also Lifeguard
Lifeguard
A lifeguard supervises the safety and rescue of swimmers, surfers, and other water sports participants such as in a swimming pool, water park, or beach. Lifeguards are strong swimmers and trained in first aid, certified in water rescue using a variety of aids and equipment depending on...

s to protect the users.

Wading or paddling pools are shallow bodies of water intended for use by small children, usually in park
Park
A park is a protected area, in its natural or semi-natural state, or planted, and set aside for human recreation and enjoyment, or for the protection of wildlife or natural habitats. It may consist of rocks, soil, water, flora and fauna and grass areas. Many parks are legally protected by...

s. Concrete wading pools come in many shapes, traditionally rectangle
Rectangle
In Euclidean plane geometry, a rectangle is any quadrilateral with four right angles. The term "oblong" is occasionally used to refer to a non-square rectangle...

, square
Square (geometry)
In geometry, a square is a regular quadrilateral. This means that it has four equal sides and four equal angles...

 or circle
Circle
A circle is a simple shape of Euclidean geometry consisting of those points in a plane that are a given distance from a given point, the centre. The distance between any of the points and the centre is called the radius....

. Some are filled and drained daily due to lack of a filter system. Staff chlorinate the water to ensure health and safety standards.

Competition pools

See: #Dimensions (above) and Swimming (sport)#Competition pools


The Fédération Internationale de la Natation
Fina
Fina may refer to:*Fina, a character in the Skies of Arcadia video game*FINA, the International Swimming Federation*FINA, the North American Forum on Integration...

 (FINA, International Swimming Federation) sets standards for competition pools: 25 or long and at least 1.35 m (4.4 ft) deep. Competition pools are generally indoors and heated to enable their use all year round, and to more easily comply with the regulations regarding temperature, lighting, and automatic officiating equipment.

An Olympic sized swimming pool (first used at the 1924 Olympics
1924 Summer Olympics
The 1924 Summer Olympics, officially known as the Games of the VIII Olympiad, were an international multi-sport event which was celebrated in 1924 in Paris, France...

) is a pool that meets FINA's additional standards for the Olympic Games and for world championship events. It must be 50 m (164 ft) in length by 25 m (82 ft) wide, divided into eight lanes of 2.5 m (8.2 ft) each plus two areas of 2.5 m (8.2 ft) at each side of the pool. The water must be kept at 25 – and the lighting level at greater than 1500 lux
Lux
The lux is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area. It is used in photometry as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface...

. Depth must be at least 2 m (6.6 ft), and there are also regulations for color of lane rope, positioning of backstroke flags (5 meters from each wall), and so on. Pools claimed to be "Olympic pools" do not always meet these regulations, as FINA cannot police use of the term. Touchpads
Aquatic timing system
Aquatic timing systems are designed to automate the process of timing, judging, and scoring in competitive swimming and other aquatic sports, including diving, water polo, and synchronised swimming...

 are mounted on both walls for long course meets and each end for short course.

A pool may be referred to as fast or slow, depending on its physical layout.
Some design considerations allow the reduction of swimming resistance
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...

 making the pool faster: namely, proper pool depth, elimination of currents, increased lane width, energy absorbing racing lane lines and gutters, and the use of other innovative hydraulic, acoustic and illumination designs.

Exercise pools

In the last two decades, a new style of pool has gained popularity. These consist of a small vessel (usually about 2.5 m x 5 m) in which the swimmer swims in place, either against the push of an artificially generated water current or against the pull of restraining devices. These pools have several names, such as swim spas, swimming machine
Swimming machine
A swimming machine is a resistance swimming apparatus, often self-contained, enabling the swimmer to swim in place. This may be accomplished either by accelerating the water past the swimmer or by supporting the swimmer, either in water or on dry land...

s
, or swim systems. They are all examples of different modes of resistance swimming
Resistance swimming
Resistance swimming is a form of swimming exercise undertaken either for athletic or therapeutic purposes. In optimal circumstances, it lends itself to any stroke the swimmer wishes to perform...

.

Hot tubs and spa pools

Hot tub
Hot tub
A hot tub is a large tub or small pool full of heated water and used for soaking, relaxation, massage, or hydrotherapy. In most cases, they have jets for massage purposes. Hot tubs are usually located outdoors, and are often sheltered for protection from the elements, as well as for privacy....

s and spa
Spa
The term spa is associated with water treatment which is also known as balneotherapy. Spa towns or spa resorts typically offer various health treatments. The belief in the curative powers of mineral waters goes back to prehistoric times. Such practices have been popular worldwide, but are...

 pools are common heated pools used for relaxation and sometimes for therapy. Commercial spas are common in the swimming pool area or sauna
Sauna
A sauna is a small room or house designed as a place to experience dry or wet heat sessions, or an establishment with one or more of these and auxiliary facilities....

 area of a health club
Health club
A health club is a place which houses exercise equipment for the purpose of physical exercise.-Main workout area:...

 or fitness centre, in men's clubs, women's clubs, motels and exclusive five star hotel suites. Spa clubs may have very large pools, some segmented into increasing temperatures. In Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, men's clubs with many spas of different size and temperature are common. Commercial spas are generally made of concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

, with a mosaic
Mosaic
Mosaic is the art of creating images with an assemblage of small pieces of colored glass, stone, or other materials. It may be a technique of decorative art, an aspect of interior decoration, or of cultural and spiritual significance as in a cathedral...

 tile
Tile
A tile is a manufactured piece of hard-wearing material such as ceramic, stone, metal, or even glass. Tiles are generally used for covering roofs, floors, walls, showers, or other objects such as tabletops...

d interior. More recently with the innovation of the Pre-Form Composite method where Mosaic tiles are bonded to the shell this enables Commercial SPA's to be completely factory manufactured to specification and delivered in one piece. Hot tubs are typically made somewhat like a wine barrel
Wine barrel
The use of oak plays a significant role in winemaking and can have a profound effect on the resulting wine, affecting the color, flavor, tannin profile and texture of the wine. Oak can come into contact with wine in the form of a barrel during the fermentation or aging periods...

 with straight sides, from wood such as Californian redwood held in place by metal hoops. Immersion of the head is not recommended in spas or hot tubs due to a potential risk of underwater entrapment from the pump suction forces. However, commercial installations in many countries must comply with various safety standards which reduce this risk considerably.

Home spas are a worldwide retail item in western countries since the 1980s, and are sold in dedicated spa stores, pool shops, department store
Department store
A department store is a retail establishment which satisfies a wide range of the consumer's personal and residential durable goods product needs; and at the same time offering the consumer a choice of multiple merchandise lines, at variable price points, in all product categories...

s, the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...

, and catalog
Mail order
Mail order is a term which describes the buying of goods or services by mail delivery. The buyer places an order for the desired products with the merchant through some remote method such as through a telephone call or web site. Then, the products are delivered to the customer...

 sales books. They are almost always made from heat-extruded acrylic sheet Perspex, often colored in marble
Marble
Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite.Geologists use the term "marble" to refer to metamorphosed limestone; however stonemasons use the term more broadly to encompass unmetamorphosed limestone.Marble is commonly used for...

 look-alike patterns. They rarely exceed 8 ft2 and are typically 3 in 6 in (1.07 m) deep, restricted by the availability of the raw sheet sizes (typically manufactured in Japan). There is often a mid-depth seating or lounging system, and contoured lounger style reclining seats are common. Upmarket spas include various jet nozzles (massage, pulsating, etc.), a drinks tray, lights, LCD flat-screen TV sets and other features that make the pool a recreation center. Due to their family-oriented nature, home spas are normally operated from 36 to 39 °C (96.8 to 102.2 F). Many pools are incorporated in a redwood or simulated wood surround, and are termed "portable" as they may be placed on a patio
Patio
A patio is an outdoor space generally used for dining or recreation that adjoins a residence and is typically paved. It may refer to a roofless inner courtyard of the sort found in Spanish-style dwellings or a paved area between a residence and a garden....

 rather than sunken into a permanent location. Some portable spas are shallow and narrow enough to fit sideways through a standard door and be used inside a room. Low power electric immersion heaters are common with home spas.

Whirlpool tubs first became popular in America during the 1960s and 1970s. A spa is also called a "jacuzzi" in USA since the word became a generic after plumbing component manufacturer Jacuzzi
Jacuzzi
Jacuzzi is a company that produces whirlpool bathtubs and spas. Its first product was a bath with massaging jets. The term "jacuzzi" is now often used generically to refer to any bathtub with massaging jets.-History:...

 introduced the "Spa Whirlpool" in 1968. Air bubbles may be introduced into the nozzle
Nozzle
A nozzle is a device designed to control the direction or characteristics of a fluid flow as it exits an enclosed chamber or pipe via an orifice....

s via an air-bleed venturi pump that combines cooler air with the incoming heated water to cool the pool if the temperature rises uncomfortably high. Some spas have a constant stream of bubbles fed via the seating area of the pool, or a footwell area. This is more common as a temperature control device where the heated water comes from a natural (uncontrolled heat) geothermal
Geothermal
Geothermal is related to energy and may refer to:* The geothermal gradient and associated heat flows from within the Earth- Renewable technology :...

 source, rather than artificially heated. Water temperature is usually very warm to hot — 38 to 42 °C (100.4 to 107.6 F), so bathers usually stay in for only 20 to 30 minutes. Bromine
Bromine
Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...

 or mineral sanitizer
Mineral sanitizer
Mineral sanitizers for the swimming pool and spa use minerals, metals, or elements derived from the natural environment to produce water quality benefits that would otherwise be produced by harsh or synthetic chemicals....

s are often recommended as sanitizers for spas because chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 dissipates at a high temperature thereby heightening its strong chemical smell. Ozone
Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

 is an effective bactericide and is commonly included in the circulation system with cartridge filtration, but not with sand media filtration due to clogging problems with turbid body fats.

Ocean pools

In the early 20th century, especially in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, ocean pools were built, typically on headlands by enclosing part of the rock shelf, with water circulated through the pools by flooding from tidal tanks or by regular flooding over the side of the pools at high tide. This continued a pre-European tradition of bathing in rockpools, or bogey holes with many of the current sites being expanded from sites used by Australian Aborigines
Australian Aborigines
Australian Aborigines , also called Aboriginal Australians, from the latin ab originem , are people who are indigenous to most of the Australian continentthat is, to mainland Australia and the island of Tasmania...

. Bathing in these pools provided security against both rough surf and against sharks. There were often separate pools for women and men, or the pool was open to the sexes at different times with a break for bathers to come without fear of observation by the other sex.
These were the fore-runners of modern 'Olympic' pools. A variation was the later development of sea- or harbour-side pools that circulated sea water using pumps. A pool of this type was the training ground for Australian Olympian Dawn Fraser
Dawn Fraser
Dawn Fraser AO, MBE is an Australian champion swimmer. She is one of only two swimmers to win the same Olympic event three times – in her case the 100 meters freestyle....

.

There are currently about 100 ocean baths in New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

, which can range from small pools roughly 25 metres long and "Olympic Sized" (50m) to the very large, such as the 50x100m baths in Newcastle
Newcastle, New South Wales
The Newcastle metropolitan area is the second most populated area in the Australian state of New South Wales and includes most of the Newcastle and Lake Macquarie Local Government Areas...

. While most are free, a number charge fees, such as the Icebergs pool at Bondi Beach. Despite the development of chlorinated and heated pools, ocean baths remain a popular form of recreation in New South Wales.

Infinity pools

An infinity edge pool (also named negative edge or vanishing edge pool) is a swimming pool which produces a visual effect of water extending to the horizon, vanishing, or extending to "infinity". Often, the water appears to fall into an ocean, lake, bay, or other similar body of water. The illusion is most effective whenever there is a significant change in elevation, though having a natural body of water on the horizon is not a limiting factor.

Natural pools and ponds

Natural pool
Natural Pool
The Natural Pool, also known as "conchi" or "Cura di Tortuga", is a natural pool of water located in a very remote area in the north of Aruba. It is formed by rock and volcanic stone circles...

s were developed in central and western Europe in the early and mid 1980s by designers and landscape architects with environmental concerns. They have recently been growing in popularity as an alternative to traditional swimming pools. NSPs are constructed bodies of water in which no chemicals or devices that disinfect or sterilize water are used, and all the cleaning of the pool is achieved purely with the motion of the water through biological filters and plants rooted hydroponically in the system. In essence, NSPs seek to recreate swimming holes and swimmable lakes, the environment where people feel safe swimming in a non-polluted, healthy, and ecologically balanced body of water.

Water in NSPs has many desirable characteristics. For example, red eyes, dried-out skin and hair, and bleached bathing suits associated with overly chlorinated water are naturally absent in NSPs. NSPs, by requiring a water garden to be a part of the system, offer different aesthetic options and can support amphibious wild life such as snails, frogs, and salamanders.

Zero-entry swimming pools

A zero-entry swimming pool, also called a beach entry swimming pool, is a swimming pool having an edge or entry that gradually slopes from the deck into the water, becoming deeper with each step, in the manner of a natural beach. As there are no stairs or ladders to navigate, this type of entry assists older people, young children and people with accessibility
Disability
A disability may be physical, cognitive, mental, sensory, emotional, developmental or some combination of these.Many people would rather be referred to as a person with a disability instead of handicapped...

 problems where gradual entry is useful.

Other uses

Swimming pools are also used for events such as underwater hockey
Underwater hockey
Underwater hockey is a global non-contact sport in which two teams compete to maneuver a puck across the bottom of a swimming pool into goals.-Play:...

, synchronized swimming
Synchronized swimming
Synchronized swImming is a hybrid form of swimming, dance and gymnastics, consisting of swimmers performing a synchronized routine of elaborate moves in the water, accompanied by music....

, water polo
Water polo
Water polo is a team water sport. The playing team consists of six field players and one goalkeeper. The winner of the game is the team that scores more goals. Game play involves swimming, treading water , players passing the ball while being defended by opponents, and scoring by throwing into a...

 and canoe polo
Canoe polo
Canoe Polo is a competitive ball sport played on water, in a defined "field", between two teams of 5 players, each in a kayak...

 as well as for teaching diving
Diving
Diving is the sport of jumping or falling into water from a platform or springboard, sometimes while performing acrobatics. Diving is an internationally-recognized sport that is part of the Olympic Games. In addition, unstructured and non-competitive diving is a recreational pastime.Diving is one...

 and lifesaving techniques. They have also been used for specialist tasks such as teaching water-ditching survival techniques for aircraft and submarine crews and astronaut
Astronaut
An astronaut or cosmonaut is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft....

 training. Round-cornered, irregular swimming pools, such as the Nude Bowl
Nude Bowl
The Nude Bowl was a popular skateboarding locale from the late 1970s to the early 1990s. The name comes from the fact that the site was once a nudist resort named "Desert Gardens Ranch."...

, were drained of water and used for vertical skateboarding
Skateboarding
Skateboarding is an action sport which involves riding and performing tricks using a skateboard.Skateboarding can be a recreational activity, an art form, a job, or a method of transportation. Skateboarding has been shaped and influenced by many skateboarders throughout the years. A 2002 report...

.

Sanitation

Swimming pool water must maintain low levels of bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 and virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

es to prevent the spread of disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...

s and pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...

s. Bacteria, algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

 and insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

 larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e can enter the pool if water is not properly sanitized. Pump
Pump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...

s, mechanical filters, and disinfectants are often used to filter the water.

Chemical disinfectants, such as chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 (usually as a hypochlorite
Hypochlorite
The hypochlorite ion, also known as chlorate anion is ClO−. A hypochlorite compound is a chemical compound containing this group, with chlorine in oxidation state +1.Hypochlorites are the salts of hypochlorous acid...

 salt, such as calcium hypochlorite
Calcium hypochlorite
Calcium hypochlorite is a chemical compound with formula 2. It is widely used for water treatment and as a bleaching agent...

) and bromine
Bromine
Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...

, are commonly used to kill pathogens. If not properly maintained, chemical sanitation can produce high levels of Disinfection byproducts. Sanitized swimming pool water can theoretically appear green if iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 or certain minerals are in the water. The green color is often attributed to oxidized copper compounds, such as copper chloride
Copper chloride
Copper forms two stable chlorides:*Copper chloride , CuCl, mineral name nantokite.*Copper chloride , CuCl2, mineral name eriochalcite....

.

Electronic oxidation water sanitation is an alternative to chlorination and ozone
Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

 ((O3)), though it typically relies upon metals which can be toxic to aquatic life in minute quantities. Oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 pools are produced via the electronic oxidation of the water molecule itself to generate the natural oxidisers hydroxyl
Hydroxyl
A hydroxyl is a chemical group containing an oxygen atom covalently bonded with a hydrogen atom. In inorganic chemistry, the hydroxyl group is known as the hydroxide ion, and scientists and reference works generally use these different terms though they refer to the same chemical structure in...

 (HO), atomic oxygen (O), hydrogen peroxide (H2O2) and molecular oxygen (O2). All of these have a higher oxidation reduction potential (ORP) value than chlorine. Electronic oxidation generates more oxidisers in under 1 minute than salt, chlorine, ozone or UV
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

 can generate in an hour. Electronic oxidation combined with low levels of copper ionization (0.5 PPM) provides effective sanitation without chlorine. Copper is toxic to aquatic life in the parts per billion range.

Covers

Swimming pool heating costs can be significantly reduced by using a pool cover. Use of a pool cover also can help reduce the amount of chemicals (chlorine, etc) required by the pool. Outdoor pools gain heat from the sun, absorbing 75%–85% of the solar energy striking the pool surface. Though a cover decreases the total amount of solar heat absorbed by the pool, the cover eliminates heat loss due to evaporation and reduces heat loss at night through its insulating properties. Most swimming pool heat loss is through evaporation.

The heating effectiveness of a cover depends on type. A transparent bubble cover is the most effective, as it allows the largest amount of solar flux into the pool itself. Thermal bubble covers are lightweight UV
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

 stabilized floating covers designed to minimize heat loss on heated swimming pools. Typically they are only fitted in spring and fall (autumn) when the temperature difference between pool water and air temperature is greatest. They raise temperature of a pool by around 20 °Fahrenheit, or 11 °Celsius, after being on the pool for a week. Bubble covers are typically applied and removed by being rolled up on a device fitted to one side of the pool (see illustration). Covers fall apart after 4 or 5 years due to sun exposure, overheating in the sun while off the pool, and chlorine attacking the plastic. Bubble covers should be removed during super chlorination.

A vinyl cover absorbs more sunlight directly, allowing temperature to rise faster, but ultimately prevents the pool from reaching as high a temperature as a clear cover. Vinyl covers consist of a heavier material and have a longer life expectancy than bubble covers. Insulated vinyl covers are also available with a thin layer of flexible insulation sandwiched between two layers of vinyl. These covers are mandatory to be fitted to all pools in areas of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 that have experienced drought since 2006. This is an effort to conserve water, as much water evaporates and transpires.

An alternative to a continuous sheet of pool covering is multiple floating disks which are deployed and removed disk by disk. They cover most of the surface of the pool and offer evaporation reduction similar to continuous covers. Various types are available, for example opaque (for UV resistance and possible reduced algal growth), transparent (for esthetics), heavy and solid (for wind resistance), light and inflatable (for ease of handling).

Safety covers:
These covers are typically attached all winter, by hooked bungee cords or hooked springs connected to the pool deck, and are usually made in a variety of materials including coated or laminated vinyl or polypropylene mesh. They are custom designed to stop leaf debris from entering the pool but more importantly they also provide safety for animals and small children when designed and installed properly. The custom safety cover was invented in 1957 by Fred Meyer Jr. of Meyco Pool Covers when he found a dead animal in his pool. Today covers are made to meet ASTM safety barrier standards and have kept animals, people and even large vehicles out of the pool. They are not popular in warmer climates, due to the five to ten minutes it takes to fit/remove them, making them inconvenient for repeated application and removal.

Pool cover automation

A pool cover can be either manually, semi-automatically, or automatically operated. Manual covers can be folded and stored in an off site location. Pool cover reels can also be used to help manually roll up the pool cover. The reel, usually on wheels, can be rolled in or out of place.

Semi-automatic covers use a motor-driven reel system. They use electrical power to roll and unroll the cover, but usually require someone to pull on the cover when unrolling, or guide the cover onto the reel when rolling up the cover. Semi-automatic covers can be built into the pool deck surrounding the pool, or can use reels on carts.

Automatic covers have permanently mounted reels that automatically cover and uncover the pool at the push of a button. They are the most expensive option, but are also the most convenient. These reels can be run from either an external motor requiring a pit to be dug beside the pool or using an internal motor that spins the reel.

Some pool covers fit into tracks along the sides of the pool. This prevents anything or anybody from getting into the pool. They even support the weight of several people. They can be run manually, semi-automatically, or automatically. Safety covers may be required by inspectors for public pools.

Winterization

In areas which reach freezing temperature, it is important to close a pool properly. This varies greatly between in-ground and above-ground pools. By taking steps to properly secure the pool, it lessens the likelihood that the superstructure will be damaged or compromised by freezing water.

Closing vinyl and fibreglass pools

In preparation for freezing temperatures, an in-ground swimming pool's pipes must be emptied. An above-ground pool should also be closed, so that ice does not drag down the pool wall, collapsing its structure. The plumbing is sealed with air, typically with rubber plugs, to prevent cracking from freezing water. The pool is typically covered to prevent leaves and other debris from falling in. The cover is attached to the pool typically using a stretch cord, similar to a bungee cord
Bungee cord
A bungee cord , also known as a shock cord, is an elastic cord composed of one or more elastic strands forming a core, usually covered in a woven cotton or polypropylene sheath...

 and hooks fitted into the pool surround. The skimmer is closed off or a floating device is placed into it to prevent it from completely freezing and cracking. Floating objects such as life rings or basketball
Basketball
Basketball is a team sport in which two teams of five players try to score points by throwing or "shooting" a ball through the top of a basketball hoop while following a set of rules...

s can be placed in the pool to avoid its freezing under the cover. Sand or DE filters must be backwashed, with the main drain plug removed and all water drained out. Drain plugs on the pool filter
Filter (water)
A water filter removes impurities from water by means of a fine physical barrier, a chemical process or a biological process. Filters cleanse water to various extents for irrigation, drinking water, aquariums, and swimming pools.-Methods of filtration:...

 are removed after the filter has been cleaned. The pool pump
Pump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...

 motor is taken under cover. Winter chemicals are added to keep the pool clean. The innovation of a composite construction of fibreglass, with an epoxy coating and porcelain ceramic tiles has led to the Pre-form, Composite-type with significant advantages over older methods; however, it also has increased sensitivity to metal staining.

In climates where there is no risk of freezing, closing down the pool for winter is not so important. Typically, the thermal cover is removed and stored. Winter sunlight can create an algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

 mess when a cover that has been left on all winter is removed. The pool is correctly pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

-balanced and super-chlorinated. One litre algaecide for every 50,000 litres of pool water should be added, and topped up each month. The pool should be filtered for one to two hours daily to keep the automated chlorination system active.

Safety

Pools present a significant risk of infant and toddler death due to drowning
Drowning
Drowning is death from asphyxia due to suffocation caused by water entering the lungs and preventing the absorption of oxygen leading to cerebral hypoxia....

. In regions where residential pools are common, drowning is a major cause of childhood fatalities. As a precaution, many municipalities have by-laws that require that residential pools be enclosed with fencing to restrict unauthorized access. The Virginia Graeme Baker Pool And Spa Safety Act
Virginia Graeme Baker Pool And Spa Safety Act
The Virginia Graeme Baker Pool And Spa Safety Act is a United States law named after the daughter of Nancy and James Baker and the granddaughter of former Secretary of State James Baker III. Graeme Baker died in a tragic incident in June 2002 when the suction from a spa drain entrapped her under...

 regulates pools to reduce the risk of entrapment.

Many products exist, such as removable baby fences, floating alarms and window/door alarms. Some pools are equipped with computer-aided drowning prevention
Pool safety camera
Pool Safety Cameras are video monitoring systems designed to reduce drowning deaths in public and private pools.-Classification:Aquatics video monitoring systems are broken into two categories:* Passive* Active...

 or other forms of electronic safety and security systems.

Suspended ceilings in indoor swimming pools are safety-relevant components. The selection of materials under tension should be done with care. Especially the selection of unsuitable stainless steels can cause problems with stress corrosion cracking
Stress corrosion cracking
Stress corrosion cracking is the unexpected sudden failure of normally ductile metals subjected to a tensile stress in a corrosive environment, especially at elevated temperature in the case of metals. SCC is highly chemically specific in that certain alloys are likely to undergo SCC only when...

.

Dress code

In public swimming pools, dress code may be stricter than on public beach
Beach
A beach is a geological landform along the shoreline of an ocean, sea, lake or river. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles or cobblestones...

es, and in indoor pools stricter than outdoor pools. For example, in countries where women can be topless on the beach, this is often not allowed in a swimming pool, and a swimsuit
Swimsuit
A swimsuit, bathing suit, or swimming costume is an item of clothing designed to be worn by men, women or children while they are engaging in a water-based activity or water sports, such as swimming, water polo, diving, surfing, water skiing, or during activities in the sun, such as sun bathing.A...

 must be worn. For men, wearing shoes, and a shirt, on a beach is acceptable, but often not in a pool.

At beaches, many people swim with clothes on and wear beachwear, but at pools (especially indoor pools) more minimal attire is often worn, such as lycra briefs for men or lycra one-piece tanksuits for women. Swimming with clothes on often results in objections from lifeguards at pools, especially indoor pools, as they can potentially weigh the swimmer down should he or she need to be rescued. In France and some other European countries, board shorts are usually not allowed for hygiene reasons. In Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...

n countries and in particular Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...

, rules about clothing and hygiene are especially strict. Bathing suits are sometimes doubled up (wearing one brief inside another) when diving from a high board, so that the swimsuit does not rip on impact with the water.

See also

  • Automated pool cleaner
    Automated pool cleaner
    An Automated Pool Cleaner is a vacuum cleaner intended to collect debris and sediment from swimming pools with minimum human intervention.-History:...

  • Bather load
    Bather load
    Bather load refers to the capacity of a municipal swimming pool, a water fountain, or similar facility. Often bather load is dictated by the capacity of water treatment equipment . Facilities intended only for decoration Bather load refers to the capacity of a municipal swimming pool, a water...

  • Lido
  • List of water games
  • Pool fence
    Pool fence
    A pool fence is a type of fence placed around backyard swimming pools, commonly to improve pool safety and to help prevent small children from accidentally falling into the pool and drowning.-Various materials:...

  • Swimming pool service technician
    Swimming pool service technician
    Swimming pool service technicians is a tradesperson that cleans Swimming pool pools and service major pool equipment such as pumps, motors, and filters....

  • Urine-indicator dye
    Urine-indicator dye
    Urine-indicator dye is a fictional substance thought to form some sort of colored cloud in a pool to indicate the presence of urine. It's commonly believed to exist in the United States, Canada, and Spain amongst other countries.-In popular culture:...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK