Swimming pool
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- For the 2003 film, see Swimming Pool.
Image:Fm stirling pool.jpg A swimming pool, swimming bath, or wading pool is an artificially enclosed body of water intended for recreational or competitive swimming, diving, or for other bathing activities that do not involve swimming, e.g. play, wading, water exercise, floating around on inner tubes, or merely cooling off on hot days. It usually contains the chemical Chlorine to control bacteria.
One can distinguish between private and public pools: in warm parts of the world private ones are usually outdoors, while public ones can be outdoors or indoors, with some complexes having both. In some parts of the world, a swimming pool for private use is considered a status symbol (an indoor private pool even more so). Swimming pools can be constructed either above ground (generally constructed from plastic and metal), or in the ground (usually formed either out of reinforced concrete and lined with special plaster, a one piece fiberglass shell, or prefabricated sectional walls and a vinyl liner).
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History
Artificial swimming pools have been built by the ancient Greeks and Romans who used them for athletic training in the palestras and also for nautical games, and military exercises. Roman emperors had private swimming pools in which fish also were kept, hence the Latin word for pool, piscina.
Types of pools
Public pools
Image:Swimming-pool.jpg 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 a backyard pool can 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; they may 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.
Competition pools
FINA sets widely recognized standards for competition pools, which must be 25 m or 50 m long and at least 1.35 m 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 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 in length by 25 m wide, divided into eight lanes of 2.5 m each plus two areas of 2.5 m at each side of the pool. The water must be kept at 25–28°C and the lighting level at greater than 1500 lux. Depth must be at least 2 m, 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.
Length
Most pools in the world are measured in metres, but in the US pools are sometimes measured in 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".
United States Swimming (USS) swims in both metric and non-metric pools. However, the international standard is metres, and world records are only recognised when swum in 50 m pools.
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.
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 tub
In the swimming pool area and/or in the sauna area there may be one or more hot tubs (small pools in which people sit on an underwater bench along the edge with water streams and air bubbles). The water temperature is usually very warm to hot, 30 to 40 °C (86 to 104 °F), so that one can only stay a limited amount of time in it, but sometimes only mildly warm, in which case one can stay as long as one likes.
Infinity pools
An infinity pool is a swimming pool which produces a visual effect of the water extending to the horizon or to "infinity". In reality the edge of the pool is below the water level, the water spilling into a trough from where it is pumped back into the pool. The effect is particularly impressive where the invisible edge appears to merge with a larger body of water such as the ocean, or with the sky (if the pool is located on the side of a hill or mountain).
Other pools
Image:Cincinnati-hyatt-indoor-pool.jpg
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.
A variety of 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, also called "baby pools", are usually small, shallow plastic pools that usually cost around $10.00 and can be found at department stores. These pools can be inflatable or made of hard plastic.
Water cleanliness and disinfection
Swimming pool water must be maintained with very low levels of bacteria and viruses to prevent the spread of diseases and pathogens between users. Strong oxidising agents are often used, especially simple chlorine compounds such as sodium hypochlorite. Other disinfectants include bromine compounds and ozone generated on site by passing an electrical discharge through oxygen or air. When chlorine is used, these can be in the form of hypochlorite solutions and by dissolving chlorine gas in water. Maintaining a safe concentration of disinfectant is critically important in assuring the safety and health of swimming pool users. When any of these pool chemicals are used, it is very important to keep the pH of the pool within a certain range (7 to 8), because either acid or alkali can cause reductions in the efficacy of the sanitiser, and bather discomfort.
Where the water is sanitised by means of oxidisers, some suppliers of electronic monitoring equipment recommend that the efficacy of the oxidiser be measured by the oxidation-reduction potential of the water, a factor measured in millivolts, where the minimum acceptable ORP level is 650 millivolts. This is supposed to ensure a 1-second kill rate for microorganisms introduced into the water. Unfortunately, a commonly used non-chlorine supplemental oxidizer, potassium monopersulfate, can produce measured 650 mV levels even in the absence of all sanitizing residuals.
Some recent studies have suggested that poorly maintained swimming pool chlorination may contribute to higher rates of childhood asthma, leading to the development of (currently expensive) chlorine-free pool filter systems which sterilise the water, exposing it to powerful ultraviolet light. Generally, a well managed pool will have no smell or taste, be scrupulously clean, and have crystal clear water. Most people would not want to swim in a pool that appears dirty even if germs were under control. Therefore pools must be filtered to remove dirt. Also, to prevent buildup of chemicals, some water must be let off and renewed. Water in larger pools is sometimes automatically recirculated through drains at the bottom of the pool.
The proper management of a backyard swimming pool can be a difficult and time-consuming task. The chemical balance of the water has to be carefully monitored to make sure that it not become fouled with algae or bacteria. Either of these will make the water smell and look unpleasant and can be a serious health hazard. The water must also be kept clear of debris such as fallen leaves and sticks, as these encourage fouling and become very slippery and dangerous as they start to decompose. Most people keep their pool either covered over or drained entirely during the months of the year in which it is not in use, as this is the easiest way to keep it sanitary (draining however can be a serious safety hazard with deeper pools and re-filling can be fairly expensive in areas where water is scarce). Public and competitive swimming pools are therefore often, especially in colder climates, indoor pools—covered with a roof and heated—to enable their use all year round.
Saltwater pools are very popular in Australia as an alternative to chlorine or ozone systems. This system uses electrolysis to break down the salt (NaCl) and free the chlorine. They have become increasingly more popular in North America in recent years due to the efficiency of the systems, and their inclusion by many pool construction companies.
Safety
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 drowning is a major cause of childhood death. 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.
In public pools there is a much higher level of safety, 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). Where safety and privacy are concerned, the trend seems to be toward safety.
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.
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 and so extra care must be taken when swimming along the sides or floor of the swimming pool.
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 also 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. Until recently, many YMCA pools required users to be naked or to have a bathingsuit made of materials that will not contaminate the pool; the words often used were "nylon bathingsuit or no bathingsuit". 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.
Other uses
Image:NASA Swimming Pool.jpg 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.
See also
- Beach
- Biocide
- Deep Eddy Pool—Oldest swimming pool in Texas
- Fish out of Water
- Lido
- Marco Polo
- Swimming machine
- Swimguard
External links
- How Stuff Works: Swimming pools - Explains how pools work
- Drowning Prevention
- Swimmer's Guide - International directory of swimming pools
- Swim Sites - Swimming web directory
- Chlorine-free Swimming - Directory project of chlorine-free swimming poolsda:Svømmebassin
de:Schwimmbecken es:Piscina fr:Piscine gl:Piscina id:Kolam renang it:Piscina nl:Zwembad ja:プール pl:Basen pt:Piscina sv:Bassäng zh:游泳池