Swimming pool

For the 2003 film, see Swimming Pool (film).

Backyard swimming pool

A swimming pool, swimming bath, or wading pool is an artificially enclosed body of water intended for swimming or water-based recreation. There are many different sizes, an Olympic sized swimming pool being the biggest and deepest.It can be constructed either above or in the ground and may be built from various materials, including metal, plastic, and concrete.

History

The history of pools begins at the "great bath" constructed at the site of Mohenjo-Daro. It was most likely dug during the 3rd millennium BC. The pool, twelve by seven meters, is lined with bricks and during its time the pool was covered with a tar-based sealant.

Artificial swimming pools have also been built by the ancient Greeks and Romans who used them for athletic training in the palaestras and also for nautical games, and military exercises. Roman emperors had private swimming pools in which fish were also kept, hence the Latin word for pool, piscina.

Ancient Sinhalese built what is known as "Kuttam Pokuna" a pair of pools in the ancient kingdom of Anuradhapura, Sri Lanka (4th Century BC). Such pools were decorated with flights of steps, punkalas or pots of abundance and scroll design.

The first heated swimming pool was built by Gaius Maecenas of Rome in the first century BC. Gaius Maecenas was a rich Roman lord and considered one of the first patron of arts.

Swimming pools did not become popular in Britain until the middle of the 19th century. By 1837, six indoor pools with diving boards were built in London, England. After the modern Olympic Games began in 1896 and swimming races were among the original events, the popularity of swimming pools began to spread (Reference Britannica).

The Amateur Swimming Association was founded in 1869 in England, but it was much later, in 1909, that Oxford Swimming Club came into existence. One might guess that the presence of indoor baths in the cobbled area of Merton Street of London persuaded the less hardy of the aquatic brigade to join. So, bathers gradually became swimmers, and bathing pools swimming pools.

Modern pools

Deep Eddy Pool, built in 1915, is the oldest concrete swimming pool in Texas

The Racquet Club of Philadelphia clubhouse (1907) boasts one of the world's first modern above ground-level swimming pools. The first swimming pool to go to sea on an ocean liner was installed on the White Star Line's Adriatic in 1907.

In 1939, Oxford, England had its first major public indoor pool at Temple Cowley. After the pool was installed, swimming began to take off and soon Oxford Swimming Club became Oxford City Swimming Club, and the Temple Cowley Pool was its home. After World War I and the departure of "Long John" style swimming costumes, the interest in competitive swimming grew. Standards improved and training became essential. Home swimming pools became popular in the USA after World War II and the publicity given to swimming sports by Hollywood (Esther Williams Million Dollar Mermaid and other "swimming" films) made a home pool a desirable status symbol. In 1956, the National Swimming Pool Institute was founded and has since been renamed the Association of Pool & Spa Professionals, currently developing pool construction standards and providing training to pool builders and service technicians. More than fifty years later, the home or residential swimming pool is ubiquitous and even the smallest world nations enjoy a thriving swimming pool industry (e.g. New Zealand pop. 4,116,900 [Source NZ Census 7 March 2006] - with 65,000 home swimming pools and 125,000 spa pools).

The World's Largest Swimming Pools

The largest swimming pool ever built was reputedly in Moscow after the Palace of Soviets remained uncompleted. The foundations were converted into an open air swimming pool after the process of de-Stalinisation. After the fall of communism, Christ the Saviour Cathedral was re-built (it had originally been on the site) between 1995 and 2000.

In the 21st century, there seems to be many contenders for "the largest swimming pool on earth", reputedly at Cox's Bazar, Bangladesh; at Club Med Camarina, Sicily; Sunlite Pool, Coney Island Cincinnati; and Garden City, Kansas with their 220 foot by 330 foot pool (67m x 100m) that holds 26,000,000 gallons (100 million litres) of water, all being in contention. A recent construction in Tokyo, Japan may top them all. The largest indoor wave pool in North America is located at the West Edmonton Mall and the largest indoor pool is at the Neutral Buoyancy Lab in the Sonny Carter Training Center at NASA JSC in Houston. The longest swimming pool is the Orthlieb Pool in Casablanca, Morocco. The pool is 480 meters or 1,574 feet long and 75 meters or 246 feet wide. The Orthlieb Pool is filled with sea water and covers 8.9 acres (3.60 Ha). [Source: Internet] The pool Nemo 33 is a recreational diving center near Brussels, Belgium that is home to the world's deepest swimming pool. The pool has two large flat-bottomed areas at depth levels of 5m (16 ft) and 10m (32 ft), and a large circular pit descending to a depth of 33m (108 ft).

The Fleishhacker Pool was the largest swimming pool in the United States. Opened on 23 April 1925, it measured 300 m by 45 m (1,000 ft by 150 ft) and was so large that the lifeguards required kayaks for patrol. It was closed in 1971 due to low patronage.

According to the Guinness World Records the largest swimming pool in the world certified by the is San Alfonso del Mar Seawater pool in Algarrobo, Chile. It is 1,013 m (3,324 ft) long and has a area of 8 ha (19.77 acre), it was completed in December 2006

Dimensions

Length

Most pools in the world are measured in metres, but in the US pools are almost always measured in feet and yards. In the UK most pools are in metres, but older pools measured in yards still exist. In the US pools tend to either be 25 yards (short course yards), 25 metres (short course metres) or 50 metres (long course). United States high schools and the NCAA conduct short course (25 yards) competition. There also exist many pools 33⅓ m in length, so that 3 lengths = 100 m. This is sometimes jokingly referred to as "inter-course".

USA Swimming (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 25m 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.

Depth

A boy in a shallow children's pool.

The depth of a swimming pool depends on the purpose of the pool, and if it is open to the public, or strictly for private use. If it is a private casual, relaxing pool, it may go from 1.0m to 1.8m (3 to 6 feet) deep. If it is a public pool designed for diving, a pool may slope from 3 to 4.8 m (10 to 14 feet) in the deep end. A children's play pool may be from 30 cm to 1.2 m (1 to 4 feet) deep. Most public pools have differing depths to accommodate different swimmer requirements. In many states, it is a requirement to show the water depth with clearly marked depths affixed to the pool walls.

Following an incident in Washington state in 1993, where 14-year-old Shawn Meneely was seriously injured (tetraplegic) in a private swimming pool in a "suicide dive" diving incident, and where family lawyer Fred Zeder successfully sued the diving board manufacturer, the pool builder, and the National Spa & Pool Institute over the inappropriate depth of the pool, most US and other pool builders are reluctant to equip a residential swimming pool with a diving springboard, so home diving pools are much less common these days. (The NSPI specified a minimum depth of 8 ft 6 in (2.55m) which proved to be insufficient in the above case). The multi-million dollar lawsuit was eventually settled in 2001 for $US6,600,000 ($US8,000,000 after interest was added) in favor of the plaintiff. The NSPI was held to be liable, and was financially strained by the case. The NSPI filed twice for Chapter 11 bankruptcy protection and was successfully reorganized into a new swimming pool industry association.

Types of pools

Ocean pools

In the early part of the 20th century, especially in Australia, ocean pools were constructed 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. 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. Segregated changing sheds and showers were provided. 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. The pool of this type at Balmain was the training ground for Olympian, Dawn Fraser.

Private pools

A small inflatable "splasher" pool

A Private Swimming pool

Privately owned outdoor swimming pools in backyards or gardens started to proliferate in the 1950s in regions with warm summer climates, particularly in the United States. Today, in some U.S. locations, home pools are so common that it is rare to find a new house being built without a swimming pool being considered in the design. Private pools are generally smaller than public pools, averaging 16' x 32' (4.8m x 9.6m) to 20' x 40' (6m x 12m) whereas public pools usually start at 80 0" (25.0m) and upwards.

Increasingly, private pools are becoming a feature of homes in more northerly locations. In London, for example, many larger homes are now being refurbished to incorporate indoor pools, usually in the basement or in a conservatory. In some European cities, including Munich, it is relatively common for people living in older properties to convert existing internal motorcar garages into indoor pool areas.

Construction methods for private pools vary greatly. Construction standards for private residential pools have been developed by the Association of Pool & Spa Professionals (APSP) and approved by the American National Standards Institute. The three main types of in-ground or sunken pools are concrete, vinyl liner, and fiberglass. Above-ground pools (sometimes called "on-ground pools") are generally lower in cost than in-ground pools. They are especially popular in northern countries, where ground freezing makes excavation difficult and threatens damage to the pool structure. Inexpensive inflatable/demountable PVC supermarket-purchased private pools, which are taken down after summer, may also be used. These are typically shallow in depth and are regarded in the swimming pool industry as "splasher" pools, not intended for swimming but rather as a cool splasher pool for young children.

Many countries now have strict pool fencing laws for private swimming pools, which dictate that the swimming pool shall be isolated from unauthorized children under the age of six years gaining access from off site. 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 general 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

Fun with inner tubes in a swimming pool.

Public pools are often found as part of a larger leisure centre or recreational complex. These centres often have more than one pool, e.g. an indoor heated pool, an outdoor saltwater or unheated chlorinated pool, a shallower children's pool, and a paddling pool for toddlers and infants. There may also be a sauna area. In the swimming pool area and/or in the sauna area there may be one or more spa pools or jacuzzis.

If a swimming pool (sometimes combined with facilities for allied sports and activities, such as a diving tank) is located in a separate building, the building is called a "natatorium".

Many public swimming pools are rectangles either 25 m or 50 m long, but may be any size and shape desired. There are also very elaborate pools, with artificial waterfalls, fountains, splash pads, wave machines, varying depths of water, bridges, and island bars. Construction standards for public pools and spas have been developed by the Association of Pool & Spa Professionals (APSP) and approved by the American National Standards Institute.

Public pools may also belong to a hotel or holiday resort.

There are often lockers for clothing and other belongings. The lockers generally require a coin to be inserted as deposit or payment outright. Also there are often showers ready for use - sometimes mandatorily before - or after, a person has finished swimming.

Competition pools

The starting block of a competition swimming pool.

FINA sets widely recognized standards for competition pools, which must be 25 m (~82 feet) or 50 m (~164 feet) long and at least 1.35 m (~4.4 feet) 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 and other swimming pool equipment.

An Olympic sized swimming pool is a pool that meets FINA's additional standards for the Olympic Games and for world championship events. It must be 50 m (~164 feet) in length by 25 m (~82 feet) wide, divided into eight lanes of 2.5 m (~8.2 feet) each plus two areas of 2.5 m (~8.2 feet) at each side of the pool. The water must be kept at 25–28°C (77-82.4°F) and the lighting level at greater than 1500 lux. Depth must be at least 2 m (~6.5 feet), and there are also regulations for color of lane rope, positioning of backstroke flags, and so on. Pools claimed to be "Olympic pools" do not always meet these regulations, as FINA cannot police use of the term.

A pool may be referred to as fast or slow, depending upon its physical layout. Some design considerations allow the reduction of swimming resistance 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 go under several names, such as swim spas, swimming machines, or swim systems. They are all examples of different modes of resistance swimming.

Hot tubs and spa pools

In the swimming pool area and/or in the sauna area of a Health Club or Fitness Centre, there may be one or more hot tubs or spa pools. Air bubbles may be introduced into the nozzels via an air-bleed venturi system that combines cooler air with the incoming heated water to cool the pool down if temperatures rise uncomfortably high. Some spa pools have a constant stream of bubbles fed via the seating area of the pool, or from the footwell area. This is more common as a temperature control device where the heated water is provided by a natural (uncontrolled heat) geothermal source, rather than artificially heated. SPA water temperature is usually experienced by the bather as "very warm to hot", or 38°C to 42°C (100 to 104 °F), so that a limited amount of time is usually spent sitting or bathing in these pools. At 39°C most bathers would stay no longer than twenty to thirty minutes. Total immersion (especially the head) is not recommended in commercial spas due to unknown health risks posed either by the large number of bathers, or activities carried out by those who may use the pool in a given time period. Commercial SPA pools are commonly found in Health Clubs, Men's Clubs, Women's Clubs, Fitness Centers, Massage Parlours or Brothels, Motels, and are often included in exclusive "Five Star" Hotel suites. SPA clubs may have very large pools segmented into increasing or decreasing temperatures in each specific pool. In Japan, the ubiquitous Men's Club with many different size & temperature spa pools is common. Commercial spa pools are generally constructed from concrete, with a mosaic tiled interior, whereas Hot Tubs are typically constructed in a manner not unlike a beer or wine barrel - but with straight sides - being constructed from Californian redwood held in place with metal containment bands or "hoops". The "Hippie" era (1950 - 1970) popularized these items in America, in both songs and movies.

Since the 1980s home spa pools have become a world-wide retail item in western countries, and are sold in dedicated spa stores, Pool Shops, Department Stores, the Internet, and even Catalog Sales Books. Home Spas are almost exclusively made from heat-extruded acrylic sheet Perspex , more often colored in marble look-alike patterns. Restricted by the availability of the raw sheet sizes (typically manufactured in Japan) home spa pools rarely exceed 8 ft² (2,400mm²) and are typically 3 ft 6 in (1 m) deep, with a mid-depth seating or lounging system. Contoured lounger style reclining seats are common, and the more upmarket pools include many nozzel jet types (massage, pulsating etc.) a drinks tray, lights, LCD flat screen TV and other features that make the pool a recreation center. Due to the more family-oriented nature of the home SPA, they would normally be operated from 36°C to 39°C. many pools are incorporated in a redwood or simulated wood surround, and are termed "Portable" as they may be placed on a patio rather than sunken into a permanent location. Some portable spas are less deep, the narrower width when stood upright allowing easy placement inside the home through a standard door width.

Due to chlorine rapidly dissipating at higher temperature, Bromine is more commonly recommended over Chlorine as a sanitizer for spa pools, and OZONE - a popular and effective bacteriocide - is commonly included in the circulation system, with cartridge filtration (not sand media filtration, due to clogging problems with turbid body fats). Low power electric immersion heaters are common with most home SPA pools. Introducing the first "Spa Whirlpool" to the USA in 1968, the plumbing component manufacturer Jacuzzi is commonly associated with these type of pools. The word "jacuzzi" has become generic and thus is synonymous with "spa pool" in the United States of America.>

Infinity pools

Main article: Infinity pool

An infinity 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".

Other pools

Swimming pool of a resort in Curaçao.

Motels often have pools, often outside, as an amenity for the recreation of their guests and children, especially motels in warmer climates. Larger pools sometimes have a diving board as an accessory affixed above the water at the pool's edge. Diving pools should meet minimum depth requirements to prevent diving injury.

Home pools can be permanently built-in, but non-permanent pools are often assembled above ground and can be disassembled. They are used mostly outdoors in yards. For toddlers and small children, small temporary-use pools made of plastic can be blown up with air to form the sides of the pool and the inside filled with water. When finished, the water and air can be let out and this type of pool can be folded up for convenient storage.

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

As an alternative, some people use hot tubs at home for recreationally soaking their bodies in water.

Wading pools are shallow bodies of water intended for use by small children primarily located in parks. Concrete wading pools come in many shapes but most traditionally are rectangular, square or circle. Wading pools are filled and drained daily due to lack of a filter system. Wading pool staff chlorinate the water to ensure health and safety standards.

Swimming pool sanitation

Main article: Swimming pool sanitation

Swimming pool water must be maintained at low levels of bacteria and viruses to prevent the spread of diseases and pathogens between users. Mechanical filters as well as chemical disinfectants are commonly used to maintain the safety of pool water.

Winterization

In areas which reach freezing temperature, it is important to close a pool properly. This varies greatly between inground and aboveground 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 above ground & inground vinyl and fibreglass Swimming pools

A rolled up Thermal Bubble pool cover, used to reduce water loss from evaporation and heat loss from the pool.

In locations that freeze in winter, the swimming pool is typically covered to prevent leaves & other debris from falling into it. There are various methods of attaching a cover to the pool, typically bungie type stretch cord and hooks fitted into the pool surround. The skimmer is either closed off, or a floating device is placed into it to prevent it from completely freezing and cracking when the pool begins to freeze. The pool itself could also benefit from a floating object (life-ring or even a basketball or two) to avoid total freezing under the debris cover. Drain Plugs on the pool filter should be removed after the filter has been cleaned. The pool motor should be taken under cover. Finally, winter chemicals should be added to keep the pool clean. The most important reason for closing an aboveground pool is so that ice does not drag down the pool wall, collapsing its structure.

In warmer climates where there is no risk of the pool freezing over, closing down the pool for winter is not so necessary. Typically, the Thermal Cover is removed and stored (Winter sunlight can create an Algae mess when a cover that has been left on all winter is removed). The pool is correctly balanced, and superchlorinated. One litre algaecide for every 50,000 litres of pool water should be added, and topped up in a month's time. The pool should be filtered for 1 to 2 hours daily to keep the automated chlorination system active.

Pool Covers

There are two main types of pool covers:

• Thermal Bubble Covers - lightweight UV stabilized floating covers designed to minimize heat loss on heated pools. Typically these are only fitted in Spring and Fall (Autumn) when temperature differential between pool water and air temperature is greatest. In drought areas of Australia, these covers are mandatory to be fitted to all pools. This is a water conservation effort, as a great deal of water is lost to evaporation and transpiration in some areas of Australia, which is currently (2006-2007) going through a long term drought. Bubble covers are typically applied and removed by being rolled up on a device fitted to one of the swimming pool (see illustration).

Bubble covers last around 4 or 5 years and then fall apart due to sun exposure and chlorine attacking the plastic, but most of all by over heating in the sun while off the pool. Bubble covers raise temperature of a pool around 20 degrees Fahrenheit after being on the pool for a week. Bubble covers should be removed during super chlorination. Most of the heat energy in a pool is lost through evaporation.

• Debris Covers - These are typically semi-permanently (all winter) attached by hooked bungee cords or hooked springs connected to the pool deck, and are usually made from black or green fine PVC mesh. These covers are designed to provide some added safety for animals and small children (not necessarily to be relied on, however) but mainly to stop leaf debris from entering the pool. These covers are not popular in warmer climates, due to the five to ten minutes it takes to fit/remove, making them inconvenient for repeated application and removal.

Closing an In-ground Swimming Pool

In preparation for freezing temperatures, an in-ground swimming pool must have its pipes cleared of water. The pool's plumbing is sealed with air, typically with rubber plugs, to prevent cracking from freezing water.

Safety

Trained Instructors teach children how to swim

It is always advisable to keep a close watch on small children around swimming pools, especially private pools that do not have professional lifeguards, as pools present a significant risk of infant and toddler death due to drowning. In regions where residential pools are common, drowning is a major cause of childhood fatalities. Adults are more likely to be aware of risks, but it is still a good idea to have more than one person around when using a private pool. As a precaution, many municipalities have bylaws that require that residential pools be enclosed with fencing to restrict unauthorized access.

In public pools there is a lower risk of accident, with trained lifeguards on duty whenever the pool is open. Because of the risk of drowning and the desire for greater safety, combined with technological advances that make such safety possible, more and more public pools are equipped with computer-aided drowning prevention or other forms of electronic and sometimes automated safety and security systems. Among these are the Poseidon system, Swimguard, and the Drowning Early Warning System (DEWS). The best way to ensure safety around swimming pools is to be educated. Knowing how a swimming pool works greatly improves safety. For instance, long haired individuals must avoid water inlets. These inlets, also known as "skimmers", are rectangular holes on the wall that are sometimes partially or completely underwater. In private swimming pools there can be one to two inlets; on public pools there can be five to twenty skimmers. Another thing to avoid are the main drains which are usually identified as round mesh covered objects on the pool floor, as poor design can occasionally result in a safety problem. Building codes and product standards have eliminated these hazards for current designs, but not all pools are up-to-date or up to standard.

Also the bigger the body of water, the greater force it needs to have the water circulating. Stronger water pumps are used on large bodies of water to keep the swimming pool healthy so extra care must be taken when swimming along the sides or floor of the swimming pool.

For individuals with recent piercings, it is advised to keep them from being submerged in pools, due to the risk of infection.

Dress code

In public swimming pools dress code may be somewhat stricter than on public beaches, 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, especially one indoors (see swimsuit). A reversal of this strictness is also common, e.g. undress code in pools is stricter than beaches. Wearing shoes, and a shirt, on a beach is acceptable, but often not in a pool. Indoor pools have stricter undress codes than outdoor pools: in outdoor pools, men are often allowed to wear t-shirts for modesty or for protection from sunburn, but in indoor pools, men are not ordinarily allowed to wear t-shirts. Swimming with clothes on (for example, as practice for the prevention of drowning, as one might fall off a boat clothed) often results in objections from lifeguards at pools, especially at indoor pools. At beaches, many people swim with their clothes on and wear beachwear, whereas at pools (especially indoor pools) more minimal forms of bathing attire, such as lycra briefs for men or lycra one-piece tanksuits for women, are often worn. For diving from towers perhaps 10m high, sometimes bathing suits are doubled up (i.e., men will often wear one brief inside another) so that the swimsuit does not rip on impact with the water. While splashing around on beaches, especially on urban beaches, looser fitting bathing attire that is more modest is often worn.

Some public swimming pools have regular hours for nude swimming, and some pools even require nudity. In the US, until the mid 1970s, many YMCA pools required users to be naked or to have a bathing suit made of materials that will not contaminate the pool; the words often used were "nylon bathing suit or no bathing suit" or "Wear nylon or go nude". More recently, dress codes in many pools have been relaxed to allow for additional modesty. Many pool operators allow people to swim fully clothed if they can prove that they have a second set of clothes that are only for use in the pool, and if they are willing to go through the showers in this second set of clothes prior to entering the pool. In France, the general rule is that board shorts are not permitted, for similar hygiene reasons.

In Scandinavian countries and in particular Iceland they have very strict rules regarding clothing and hygiene.

Other uses

An astronaut prepares to descend into a swimming pool

Swimming pools are also used for events such as synchronized swimming and water polo as well as for teaching diving and lifesaving techniques. They have also been used for specialist tasks such as teaching water-ditching survival techniques for helicopter crews and astronaut training. Round-cornered, irregular swimming pools, drained of water, were the first surfaces used for vertical skateboarding.

See also

• Beach
• Lido
• Swimming pool sanitation
• Pool fence
• Swimming pool games

External links

• How Stuff Works: Swimming pools - Explains how pools work
• Swimmer's Guide - Comprehensive International directory of swimming pools
• Pool and Spa Safety Publications from the U.S. Consumer Product Safety Commission
• The Association of Pool & Spa Professionals (APSP) - leading trade association of the U.S. pool/spa and hot tub industry