Swimming pool sanitation
Encyclopedia
Swimming pool sanitation refers to methods for ensuring healthy conditions in swimming pool
s, lap pools, hot tub
s, plunge pool
s, and similar recreational water venues. Proper sanitation is needed to maintain the visual clarity of water and to prevent the transmission of infectious disease
s.
s, disinfection to kill infectious microorganism
s, swimmer hygiene
to minimize the introduction of contaminants into pool water, and regular testing of pool water, including chlorine
and pH
levels.
has published international guidelines for the safety of swimming pools and similar recreational-water environments, including standards for minimizing microbial and chemical hazards. The U.S. Centers for Disease Control and Prevention
also provides information on pool sanitation and water related illnesses for health professionals and the public.
are introduced from environmental sources and swimmers. Affecting primarily outdoor swimming pools, environmental contaminants include windblown dirt and debris, incoming water from unsanitary sources, rain
containing microscopic algae
spores and droppings from birds possibly harboring disease-causing viruses. Indoor pools are less susceptible to environmental contaminants.
Contaminants introduced by swimmers can dramatically influence the operation of indoor and outdoor swimming pools. Sources include micro-organisms from infected swimmers and body oils including sweat, cosmetics
, suntan lotion
, urine
, saliva
and fecal matter
. In addition, the interaction between disinfectants and pool water contaminants can produce a mixture of chloramines and other disinfection by-product
s.
Pathogenic contaminants are of greatest concern in swimming pools as they have been associated with numerous recreational water illnesses (RWIs). Public health pathogens can be present in swimming pools as viruses, bacteria, protozoa and fungi
. Diarrhea
is the most commonly reported illness associated with pathogenic contaminants, while other diseases associated with untreated pools are Cryptosporidiosis
and Giardiasis
. Other illnesses commonly occurring in poorly maintained swimming pools include otitis externa
, commonly called swimmers ear, skin rashes and respiratory infections.
A well-maintained, properly operating pool filtration
and re-circulation system is the first barrier in combating contaminants large enough to be filtered. Rapid removal of filterable contaminants reduces the impact on the disinfection system thereby limiting the formation of chloramine
s, restricting the formation of disinfection by-product
s and optimizing sanitation effectiveness. To kill pathogens and help prevent recreational water illnesses, pool operators must maintain proper levels of chlorine or another sanitizer.
management program for pool and spa operators. Disinfection is critical to protect against pathogens, and is best managed through routine monitoring and maintenance of chemical feed equipment to ensure optimum chemical levels in accordance with state and local regulations. Ideal chemical parameters include disinfectant levels according to regulated pesticide label directions, pH
between 7.2-7.8, total alkalinity of 80-120 ppm and calcium hardness between 200 – 400 ppm.
The education of parents of small children and other people with regard to good hygienic behavior
at swimming pools is also important for improving health safety at swimming pools and spas. Showering before swimming can reduce introduction of contaminants. Those with diarrhea
or other gastroenteritis
illnesses should not swim, especially children. To minimize exposure to pathogens, swimmers should avoid getting water into their mouths and never swallow pool or spa water.
(ORP), while lower pH causes bather discomfort, especially to the eyes. However, according to the Hamilton Index, a higher pH can reduce unnecessary chlorine consumption while still remaining effective at preventing algae and bacteria growth.
To help ensure the health of bathers and protect pool equipment, it is essential to perform routine monitoring of water quality factors (or "parameters") on a regular basis. This process becomes the essence of an optimum water quality management program.
Conventional halogen-based oxidizers such as chlorine
and bromine
are convenient and economical primary sanitizers for swimming pools and provide a residual level of sanitizer that remains in the water. Chlorine-releasing compounds are the most popular and frequently used in swimming pools whereas bromine-releasing compounds have found heightened popularity in spas and hot tubs. Both are members of the halogen
family with demonstrated ability to destroy and deactivate a wide range of potentially dangerous bacteria and viruses in swimming pools and spas. Both exhibit three essential elements as ideal first-line-of-defense sanitizers for swimming pools and spas: they are fast-acting and enduring; they are effective algaecides; and exhibit strong oxidizer action of undesired contaminants.
Swimming pools can be disinfected with a variety of chlorine-releasing compounds. The most basic of these compounds is elemental chlorine gas (Cl2); however, its application is primarily in large commercial public swimming pools. Inorganic forms of chlorine-releasing compounds frequently used in residential and public swimming pools include sodium hypochlorite commonly known as liquid bleach or simply bleach
, calcium hypochlorite
and lithium hypochlorite
. Chlorine residuals from elemental chlorine and inorganic chlorine-releasing compounds break down rapidly in sunlight
. To extend their disinfectant usefulness and persistence in outdoor settings, swimming pools treated with one or more of the inorganic forms of chlorine-releasing compounds can be supplemented with cyanuric acid
-- a granular stabilizing agent capable of extending the active chlorine residual half-life
(t½) by four to sixfold. Chlorinated isocyanurates, a family of organic chlorine-releasing compounds, are stabilized to prevent UV degradation due to the presence of cyanurate as part of their chemical backbone.
Chlorine reacting with urea
in urine and other nitrogen-containing wastes from bathers can produce chloramines. Chloramines typically occur when an insufficient amount of chlorine is used to disinfect a contaminated pool. Chloramines are generally responsible for the noxious, irritating smell prominently occurring in indoor pool settings. A common way to remove chloramines is to "super-chlorinate" (commonly called "shocking") the pool with a high dose of inorganic chlorine sufficient to deliver 10 ppm chlorine. Regular superchlorination (every two weeks in summer) helps to eliminate these unpleasant odors in the pool. Levels of chloramines and other volatile compounds in water can be minimized by reducing contaminants that lead to their formation (e.g., urea, creatinine, amino acids and personal care products) as well as by use of non-chlorine "shock oxidizers" such as potassium peroxymonosulfate
.
es (AOPs) can be employed whereby water contaminants are oxidized by one or more of four different precursors: ozone
, hydrogen peroxide, oxygen, and air in combination with UV radiation and in some instances a catalyst such as titanium dioxide
(TiO2). These AOPs react with water (H2O) to produce powerful oxidants such as hydroxyl radical
(OH·), singlet oxygen
(O) and molecular oxygen
(O2).
is the prime motivator in recirculating the water from the pool. Water is forced through a filter and then returned to the pool. A typical pool pump uses 500 watts to 2,000 watts. Commercial and public pool pumps usually run 24 hours a day for the entire operating season of the pool. Residential pool pumps are typical run for 4 hours per day in winter (when the pool is not in use) and up to 24 hours in summer. To save electricity costs most people run for between 6 hours and 12 hours in summer with the pump being controlled by an electronic timer
. Commercial pools require a minimum 4 hour circulation of the total water volume. Some use of solar panel generation power for the pumps is done in the Southwestern United States
, along with Solar hot water panel pool water heaters.
Some pool pumps have two motor speeds to reduce power consumption at times when full power is not needed. Other pump manufacturers (typically Italian or other European) have redesigned their units to use a smaller electric motor with heavier windings, therefore consuming less energy, to power a larger pump impeller
. Variable-speed pumps reduce power consumption even more. Popular in the United States, these pumps run slowly 24 hours a day. The slow speed typically cleans better because smaller particles can be filtered. At the slow speed, minimal resistance in the pipes reduces the energy needed to move the water.
Pool pumps typically are "self priming": they may be positioned above the mean water level of the pool yet still start up and function after a timed rest period. Pumps that do not "self prime" are termed "flooded suction" and must be gravity fed by the pump by being located below the mean level of the pool water.
Most pool pumps available today incorporate a small filter basket termed a "hair and lint strainer" or "lint pot" as the last effort to avoid leaf or hair contamination reaching the close-tolerance impeller section of the pump.
is termed a 'High Rate' sand filter, and will generally filter turbid water of particulates no less than 10 micrometers
in size. The rapid sand filter
type are periodically 'back washed' as contaminants reduce water flow and increase back pressure. Indicated by a pressure gauge on the pressure side of the filter reaching into the 'red line' area, the pool owner is alerted to the need to 'backwash' the unit. The sand in the filter will typically last five to seven years before all the "rough edges" are worn off and the more tightly packed sand no longer works as intended. Recommended filtration for public/commercial pools are 1 ton sand per 100,000 liters water.
Introduced in the early 1900s was another type of sand filter; the 'Rapid Sand' filter, whereby water was pumped into the top of a large volume tank (3' 0" or more cube) containing filter grade sand, and returning to the pool through a pipe at the bottom of the tank. As there is no pressure inside this tank, they were also known as 'gravity filters'. These type of filters are not greatly effective, and are no longer common in home swimming pools, being replaced by the pressure-fed type filter.
to help filter out contaminants. Commonly referred to as 'D.E.' filters, they exhibit superior filtration capabilities. Often a D.E. filter will trap water-borne contaminants as small as 1 micrometer in size. D.E. filters are banned in some states, as they must be emptied out periodically and the contaminated media flushed down the sewer, causing a problem in some districts' sewage systems.
connection. They are popular where backwashed water from a sand filter is not allowed to be discharged or goes into the aquifer
.
(operating from a vertical position to 90 degrees angle away from the pool, in order to stop leaves and debris being back-flooded into the pool by wave action), and down into a removable "skimmer basket", the purpose of which is to entrap leaves and other floating debris.
The aperture visible from the pool side is typically 1' 0" wide by 6" high, which intersects the water midway though the center of the aperture. Skimmers with apertures wider than this are termed "wide angle" skimmers and may be as much as 2' 0" wide (600 mm). Floating skimmers have the advantage of not being affected by the level of the water as these are adjusted to work with the rate of pump suction and will retain optimum skimming regardless of water level leading to a markedly reduced amount of bio-material in the water. Skimmers should always have a leaf basket or filter between it and the pump to avoid blockages in the pipes leading to the pump and filter.
system to trap any overflowing water.
Overflow channels allow faster turnover of the surface water than is possible with simple weir skimmers, which is why they are commonly found in public pools. They can also be attractive designs, particularly when transformed into a total Infinity edge pool. This design has been used to great effect in prize winning contemporary home design, notably in Southern California
and the surrounding desert
states.
One recent development in skimmers was the 1970s "Aquagenie(TM)" which differers considerably operationally from conventional skimmers—most of which are quite similar in operation, if not appearance—by both drawing the pool water and returning it to the same location through a submerged slot which diverts the water downwards and in a wide fan shape. The concept incorporates a reservoir
system to contain saturated trichor tablets which the resulting high strength chlorinated water dribbles back into the recirculation system, so it doubles up as a chlorine feeder as well as a normal skimmer. Arguably an "improvement" in skimmer design, patents on the device expired in 2003 and the system is now available from several US manufacturers.
pumps, natural gas or propane gas heater
s, electric heaters, and Solar hot water panel heaters - increasingly used in sustainable design
of pools.
and rain
; and as motor noise-sound insulation for the pool users and neighboring properties. Typically, these structures range in size from a simple flip-lid three-sided sound-insulated box set against a convenient house wall, the lid being constructed on a 15 to 20 degree slope and the interior large enough to hold the filter plant, pump, and whatever chlorination system has been included.
Some structures are, in addition to a separate sound-proofed pool equipment location, a Pool House (Pool Cabana - "Pool Shed") with a bathroom
, shower, changing, and storage area; and sometimes a full-size building with an: entertainment and recreation room, a small kitchen, and "guest house" accommodations. Consistent vigilance for the safety of young children in and around the pool, often by a designated adult, is important where social distraction is possible.
s and waterfall
s, in-pool fountain
s, integrated hot tub
s and spas, water slide
s and sluices, artificial "pebble beaches," submerged seating as bench-ledges or as"stools" at in-pool bars, plunge pool
s, and shallow children's wading pools.
Landscape designers often integrate the pool and its amenities and surrounding decking with the property's garden
s and the residence
. Outdoor kitchens, barbecue
s and pizza ovens, walkways and patios, plantings, shade structures, garden furniture and outdoor fireplace
s, and landscape lighting in the pool and the garden, all can expand the recreational and aesthetic possibilities of a well sanitized sparkling pool.
Swimming pool
A swimming pool, swimming bath, wading pool, or simply a pool, is a container filled with water intended for swimming or water-based recreation. There are many standard sizes; the largest is the Olympic-size swimming pool...
s, lap 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, plunge pool
Plunge pool
A plunge pool can be a natural hydrologic fluvial landform feature or a constructed recreational garden feature...
s, and similar recreational water venues. Proper sanitation is needed to maintain the visual clarity of water and to prevent the transmission of infectious 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.
Methods
Sanitation methods include filtration to remove pollutantPollutant
A pollutant is a waste material that pollutes air, water or soil, and is the cause of pollution.Three factors determine the severity of a pollutant: its chemical nature, its concentration and its persistence. Some pollutants are biodegradable and therefore will not persist in the environment in the...
s, disinfection to kill infectious microorganism
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...
s, swimmer hygiene
Hygiene
Hygiene refers to the set of practices perceived by a community to be associated with the preservation of health and healthy living. While in modern medical sciences there is a set of standards of hygiene recommended for different situations, what is considered hygienic or not can vary between...
to minimize the introduction of contaminants into pool water, and regular testing of pool water, including 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...
and 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...
levels.
Guidelines
The World Health OrganizationWorld Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
has published international guidelines for the safety of swimming pools and similar recreational-water environments, including standards for minimizing microbial and chemical hazards. The U.S. Centers for Disease Control and Prevention
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...
also provides information on pool sanitation and water related illnesses for health professionals and the public.
Reason: Contaminants and Disease
Swimming pool contaminantsContamination
Contamination is the presence of a minor and unwanted constituent in material, physical body, natural environment, at a workplace, etc.-Specifics:"Contamination" also has more specific meanings in science:...
are introduced from environmental sources and swimmers. Affecting primarily outdoor swimming pools, environmental contaminants include windblown dirt and debris, incoming water from unsanitary sources, rain
Rain
Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...
containing microscopic 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...
spores and droppings from birds possibly harboring disease-causing viruses. Indoor pools are less susceptible to environmental contaminants.
Contaminants introduced by swimmers can dramatically influence the operation of indoor and outdoor swimming pools. Sources include micro-organisms from infected swimmers and body oils including sweat, cosmetics
Cosmetics
Cosmetics are substances used to enhance the appearance or odor of the human body. Cosmetics include skin-care creams, lotions, powders, perfumes, lipsticks, fingernail and toe nail polish, eye and facial makeup, towelettes, permanent waves, colored contact lenses, hair colors, hair sprays and...
, suntan lotion
Sunscreen
Sunblock is a lotion, spray, gel or other topical product that absorbs or reflects some of the sun's ultraviolet radiation on the skin exposed to sunlight and thus helps protect against sunburn...
, urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
, saliva
Saliva
Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...
and fecal matter
Human feces
Human feces , also known as a stool, is the waste product of the human digestive system including bacteria. It varies significantly in appearance, according to the state of the digestive system, diet and general health....
. In addition, the interaction between disinfectants and pool water contaminants can produce a mixture of chloramines and other disinfection by-product
Disinfection by-product
Disinfection by-products result from reactions between organic and inorganic matter in water with chemical treatment agents during the water disinfection process.-Chlorination disinfection by-products:...
s.
Pathogenic contaminants are of greatest concern in swimming pools as they have been associated with numerous recreational water illnesses (RWIs). Public health pathogens can be present in swimming pools as viruses, bacteria, protozoa and fungi
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
. Diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
is the most commonly reported illness associated with pathogenic contaminants, while other diseases associated with untreated pools are Cryptosporidiosis
Cryptosporidiosis
Cryptosporidiosis, also known as crypto, is a parasitic disease caused by Cryptosporidium, a protozoan parasite in the phylum Apicomplexa. It affects the intestines of mammals and is typically an acute short-term infection...
and Giardiasis
Giardiasis
Giardiasis or beaver fever in humans is a diarrheal infection of the small intestine by a single-celled organism Giardia lamblia. Giardiasis occurs worldwide with a prevalence of 20–30% in developing countries. In the U.S., 20,000 cases are reported to the CDC annually, but the true annual...
. Other illnesses commonly occurring in poorly maintained swimming pools include otitis externa
Otitis externa
Otitis externa is an inflammation of the outer ear and ear canal. Along with otitis media, external otitis is one of the two human conditions commonly called "earache". It also occurs in many other species. Inflammation of the skin of the ear canal is the essence of this disorder...
, commonly called swimmers ear, skin rashes and respiratory infections.
Maintenance and hygiene
Contamination can be minimized by good swimmer hygiene practices such as showering before swimming, not swimming or letting children swim with intestinal disorders. Because preventing the introduction of pool contaminants, pathogenic and non-pathogenic, into swimming pools is impossible, effective treatments are needed to address contaminants in pool water.A well-maintained, properly operating pool filtration
Filtration
Filtration is commonly the mechanical or physical operation which is used for the separation of solids from fluids by interposing a medium through which only the fluid can pass...
and re-circulation system is the first barrier in combating contaminants large enough to be filtered. Rapid removal of filterable contaminants reduces the impact on the disinfection system thereby limiting the formation of chloramine
Chloramine
Chloramines are derivatives of ammonia by substitution of one, two or three hydrogen atoms with chlorine atoms. Monochloramine is an inorganic compound with the formula NH2Cl. It is an unstable colourless liquid at its melting point of -66° temperature, but it is usually handled as a dilute...
s, restricting the formation of disinfection by-product
Disinfection by-product
Disinfection by-products result from reactions between organic and inorganic matter in water with chemical treatment agents during the water disinfection process.-Chlorination disinfection by-products:...
s and optimizing sanitation effectiveness. To kill pathogens and help prevent recreational water illnesses, pool operators must maintain proper levels of chlorine or another sanitizer.
Prevention of diseases in swimming pools and spas
Disease prevention should be a priority for every water qualityWater quality
Water quality is the physical, chemical and biological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose. It is most frequently used by reference to a set of standards against which...
management program for pool and spa operators. Disinfection is critical to protect against pathogens, and is best managed through routine monitoring and maintenance of chemical feed equipment to ensure optimum chemical levels in accordance with state and local regulations. Ideal chemical parameters include disinfectant levels according to regulated pesticide label directions, 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...
between 7.2-7.8, total alkalinity of 80-120 ppm and calcium hardness between 200 – 400 ppm.
The education of parents of small children and other people with regard to good hygienic behavior
Hygiene
Hygiene refers to the set of practices perceived by a community to be associated with the preservation of health and healthy living. While in modern medical sciences there is a set of standards of hygiene recommended for different situations, what is considered hygienic or not can vary between...
at swimming pools is also important for improving health safety at swimming pools and spas. Showering before swimming can reduce introduction of contaminants. Those with diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
or other gastroenteritis
Gastroenteritis
Gastroenteritis is marked by severe inflammation of the gastrointestinal tract involving both the stomach and small intestine resulting in acute diarrhea and vomiting. It can be transferred by contact with contaminated food and water...
illnesses should not swim, especially children. To minimize exposure to pathogens, swimmers should avoid getting water into their mouths and never swallow pool or spa water.
Standards
Maintaining an effective concentration of disinfectant is critically important in assuring the safety and health of swimming pool and spa users. When any of these pool chemicals are used, it is very important to keep the pH of the pool in the range 7.2 to 7.8-according to the Langelier Saturation Index, or 7.8 to 8.2- according to the Hamilton Index; higher pH drastically reduces the sanitizing power of the chlorine due to reduced oxidation-reduction potentialReduction potential
Reduction potential is a measure of the tendency of a chemical species to acquire electrons and thereby be reduced. Reduction potential is measured in volts , or millivolts...
(ORP), while lower pH causes bather discomfort, especially to the eyes. However, according to the Hamilton Index, a higher pH can reduce unnecessary chlorine consumption while still remaining effective at preventing algae and bacteria growth.
To help ensure the health of bathers and protect pool equipment, it is essential to perform routine monitoring of water quality factors (or "parameters") on a regular basis. This process becomes the essence of an optimum water quality management program.
Chlorine and bromine methods
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...
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 convenient and economical primary sanitizers for swimming pools and provide a residual level of sanitizer that remains in the water. Chlorine-releasing compounds are the most popular and frequently used in swimming pools whereas bromine-releasing compounds have found heightened popularity in spas and hot tubs. Both are members of the halogen
Halogen
The halogens or halogen elements are a series of nonmetal elements from Group 17 IUPAC Style of the periodic table, comprising fluorine , chlorine , bromine , iodine , and astatine...
family with demonstrated ability to destroy and deactivate a wide range of potentially dangerous bacteria and viruses in swimming pools and spas. Both exhibit three essential elements as ideal first-line-of-defense sanitizers for swimming pools and spas: they are fast-acting and enduring; they are effective algaecides; and exhibit strong oxidizer action of undesired contaminants.
Swimming pools can be disinfected with a variety of chlorine-releasing compounds. The most basic of these compounds is elemental chlorine gas (Cl2); however, its application is primarily in large commercial public swimming pools. Inorganic forms of chlorine-releasing compounds frequently used in residential and public swimming pools include sodium hypochlorite commonly known as liquid bleach or simply bleach
Bleach
Bleach refers to a number of chemicals that remove color, whiten, or disinfect, often via oxidation. Common chemical bleaches include household chlorine bleach , lye, oxygen bleach , and bleaching powder...
, 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 lithium hypochlorite
Lithium hypochlorite
Lithium hypochlorite is the colorless, crystalline lithium salt of hypochlorous acid with the chemical formula of LiClO. It is used as a disinfectant for pools and a reagent for some chemical reactions.-Safety:...
. Chlorine residuals from elemental chlorine and inorganic chlorine-releasing compounds break down rapidly in sunlight
Sunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...
. To extend their disinfectant usefulness and persistence in outdoor settings, swimming pools treated with one or more of the inorganic forms of chlorine-releasing compounds can be supplemented with cyanuric acid
Cyanuric acid
Cyanuric acid or 1,3,5-triazine-2,4,6-triol is a chemical compound with the formula 3. Like many industrially useful chemicals, this triazine has many synonyms. This white, odorless solid finds use as a precursor or a component of bleaches, disinfectants, and herbicides...
-- a granular stabilizing agent capable of extending the active chlorine residual half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
(t½) by four to sixfold. Chlorinated isocyanurates, a family of organic chlorine-releasing compounds, are stabilized to prevent UV degradation due to the presence of cyanurate as part of their chemical backbone.
Chlorine reacting with urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
in urine and other nitrogen-containing wastes from bathers can produce chloramines. Chloramines typically occur when an insufficient amount of chlorine is used to disinfect a contaminated pool. Chloramines are generally responsible for the noxious, irritating smell prominently occurring in indoor pool settings. A common way to remove chloramines is to "super-chlorinate" (commonly called "shocking") the pool with a high dose of inorganic chlorine sufficient to deliver 10 ppm chlorine. Regular superchlorination (every two weeks in summer) helps to eliminate these unpleasant odors in the pool. Levels of chloramines and other volatile compounds in water can be minimized by reducing contaminants that lead to their formation (e.g., urea, creatinine, amino acids and personal care products) as well as by use of non-chlorine "shock oxidizers" such as potassium peroxymonosulfate
Potassium peroxymonosulfate
Potassium peroxymonosulfate is widely used as an oxidizing agent...
.
Other methods
Conditions sometimes exist in heavily-used commercial and/or public swimming pools whereby supplemental oxidation is warranted. In these instances Advanced Oxidation ProcessAdvanced Oxidation Process
Advanced oxidation processes refers to a set of chemical treatment procedures designed to remove organic and inorganic materials in waste water by oxidation...
es (AOPs) can be employed whereby water contaminants are oxidized by one or more of four different precursors: 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...
, hydrogen peroxide, oxygen, and air in combination with UV radiation and in some instances a catalyst such as titanium dioxide
Titanium dioxide
Titanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula . When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase. It has a wide range of...
(TiO2). These AOPs react with water (H2O) to produce powerful oxidants such as hydroxyl radical
Hydroxyl radical
The hydroxyl radical, •OH, is the neutral form of the hydroxide ion . Hydroxyl radicals are highly reactive and consequently short-lived; however, they form an important part of radical chemistry. Most notably hydroxyl radicals are produced from the decomposition of hydroperoxides or, in...
(OH·), singlet oxygen
Singlet oxygen
Singlet oxygen is the common name used for the diamagnetic form of molecular oxygen , which is less stable than the normal triplet oxygen. Because of its unusual properties, singlet oxygen can persist for over an hour at room temperature, depending on the environment...
(O) and molecular 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...
(O2).
Water pumps
An electrically operated water pumpWater Pump
Water Pump is one of the neighbourhoods of Gulberg Town in Karachi, Sindh, Pakistan. It is near main Water Pump that supplies fresh water to the city of Karachi....
is the prime motivator in recirculating the water from the pool. Water is forced through a filter and then returned to the pool. A typical pool pump uses 500 watts to 2,000 watts. Commercial and public pool pumps usually run 24 hours a day for the entire operating season of the pool. Residential pool pumps are typical run for 4 hours per day in winter (when the pool is not in use) and up to 24 hours in summer. To save electricity costs most people run for between 6 hours and 12 hours in summer with the pump being controlled by an electronic timer
Timer
A timer is a specialized type of clock. A timer can be used to control the sequence of an event or process. Whereas a stopwatch counts upwards from zero for measuring elapsed time, a timer counts down from a specified time interval, like an hourglass.Timers can be mechanical, electromechanical,...
. Commercial pools require a minimum 4 hour circulation of the total water volume. Some use of solar panel generation power for the pumps is done in the Southwestern United States
Southwestern United States
The Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...
, along with Solar hot water panel pool water heaters.
Some pool pumps have two motor speeds to reduce power consumption at times when full power is not needed. Other pump manufacturers (typically Italian or other European) have redesigned their units to use a smaller electric motor with heavier windings, therefore consuming less energy, to power a larger pump impeller
Impeller
An impeller is a rotor inside a tube or conduit used to increase the pressure and flow of a fluid.- Impellers in pumps :...
. Variable-speed pumps reduce power consumption even more. Popular in the United States, these pumps run slowly 24 hours a day. The slow speed typically cleans better because smaller particles can be filtered. At the slow speed, minimal resistance in the pipes reduces the energy needed to move the water.
Pool pumps typically are "self priming": they may be positioned above the mean water level of the pool yet still start up and function after a timed rest period. Pumps that do not "self prime" are termed "flooded suction" and must be gravity fed by the pump by being located below the mean level of the pool water.
Most pool pumps available today incorporate a small filter basket termed a "hair and lint strainer" or "lint pot" as the last effort to avoid leaf or hair contamination reaching the close-tolerance impeller section of the pump.
Sand
A pressure-fed filter is typically placed in line immediately after the water pump. The filter typically contains a media such as graded sand (called '14/24 Filter Media' in the UK system of grading the size of sand by sifting through a fine brass-wire mesh of 14 to the inch to 24 to the inch). A pressure fed sand filterSand filter
Sand filters are used for water purification. There are three main types;# rapid sand filters# upflow sand filters# slow sand filtersAll three methods are used extensively in the water industry throughout the world...
is termed a 'High Rate' sand filter, and will generally filter turbid water of particulates no less than 10 micrometers
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
in size. The rapid sand filter
Rapid sand filter
The rapid sand filter or rapid gravity filter is a type of filter used in water purification and is commonly used in municipal drinking water facilities as part of a multiple-stage treatment system...
type are periodically 'back washed' as contaminants reduce water flow and increase back pressure. Indicated by a pressure gauge on the pressure side of the filter reaching into the 'red line' area, the pool owner is alerted to the need to 'backwash' the unit. The sand in the filter will typically last five to seven years before all the "rough edges" are worn off and the more tightly packed sand no longer works as intended. Recommended filtration for public/commercial pools are 1 ton sand per 100,000 liters water.
Introduced in the early 1900s was another type of sand filter; the 'Rapid Sand' filter, whereby water was pumped into the top of a large volume tank (3' 0" or more cube) containing filter grade sand, and returning to the pool through a pipe at the bottom of the tank. As there is no pressure inside this tank, they were also known as 'gravity filters'. These type of filters are not greatly effective, and are no longer common in home swimming pools, being replaced by the pressure-fed type filter.
Diatomaceous Earth
Some filters use Diatomaceous earthDiatomaceous earth
Diatomaceous earth also known as diatomite or kieselgur/kieselguhr, is a naturally occurring, soft, siliceous sedimentary rock that is easily crumbled into a fine white to off-white powder. It has a particle size ranging from less than 1 micrometre to more than 1 millimetre, but typically 10 to...
to help filter out contaminants. Commonly referred to as 'D.E.' filters, they exhibit superior filtration capabilities. Often a D.E. filter will trap water-borne contaminants as small as 1 micrometer in size. D.E. filters are banned in some states, as they must be emptied out periodically and the contaminated media flushed down the sewer, causing a problem in some districts' sewage systems.
Cartridge filters
Other filter media that have been introduced to the residential swimming pool market since 1970 include sand particles and paper type cartridge filters of 50 to 150 square feet (13.9 m²) filter area arranged in a tightly packed 12" diameter x 24" long (300 mm x 600 mm) accordion-like circular cartridge. These units can be 'daisy-chained' together to collectively filter almost any size home pool. The cartridges are typically cleaned by removal from the filter body and hosing-off down a sewerSanitary sewer
A sanitary sewer is a separate underground carriage system specifically for transporting sewage from houses and commercial buildings to treatment or disposal. Sanitary sewers serving industrial areas also carry industrial wastewater...
connection. They are popular where backwashed water from a sand filter is not allowed to be discharged or goes into the aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
.
Other systems
Saline chlorination units, electronic oxidation systems, Ionization systems, microbe disinfection with ultra-violet lamp systems, and "Tri-Chlor Feeders" are other independent or auxiliary systems for Swimming pool sanitation;Consecutive dilution
A pool filtration system as described (above) is termed a "consecutive dilution" system, as a constant and consecutive stream of fresh, chlorinated, and filtered water is being continually returned to the pool as part of a process that could ultimately result in a pool with 100% newly introduced fresh water over a period of time. Of course this goal is never achieved, as there is also a constant stream of new contaminants entering the pool as subsequent sections of this page will indicate.Coping apertures
Water is typically drawn from the pool via a rectangular aperture in the wall connected through to a device fitted into one (or more) wall/s of the pool. The internals of the skimmer are accessed from the pool deck through a circular or rectangle lid, about one foot in diameter. On lifting the lid you will see water being drawn from the pool (if the pool water pump is operational), over a floating weirWeir
A weir is a small overflow dam used to alter the flow characteristics of a river or stream. In most cases weirs take the form of a barrier across the river that causes water to pool behind the structure , but allows water to flow over the top...
(operating from a vertical position to 90 degrees angle away from the pool, in order to stop leaves and debris being back-flooded into the pool by wave action), and down into a removable "skimmer basket", the purpose of which is to entrap leaves and other floating debris.
The aperture visible from the pool side is typically 1' 0" wide by 6" high, which intersects the water midway though the center of the aperture. Skimmers with apertures wider than this are termed "wide angle" skimmers and may be as much as 2' 0" wide (600 mm). Floating skimmers have the advantage of not being affected by the level of the water as these are adjusted to work with the rate of pump suction and will retain optimum skimming regardless of water level leading to a markedly reduced amount of bio-material in the water. Skimmers should always have a leaf basket or filter between it and the pump to avoid blockages in the pipes leading to the pump and filter.
Perimeter Overflow channels
An overflow channel is a gutter that surrounds the pool, covered by a removable grille. Surface water flows over the edge of the pool and runs by gravity to the filtration plant, usually via a catchment and top-up tank. Often the exterior pool wall is higher than the overflow channel, eliminating the possibility of pool water overflowing onto the adjacent pool surround. Other designs may not have this feature, relying instead on a wider drainageDrainage
Drainage is the natural or artificial removal of surface and sub-surface water from an area. Many agricultural soils need drainage to improve production or to manage water supplies.-Early history:...
system to trap any overflowing water.
Overflow channels allow faster turnover of the surface water than is possible with simple weir skimmers, which is why they are commonly found in public pools. They can also be attractive designs, particularly when transformed into a total Infinity edge pool. This design has been used to great effect in prize winning contemporary home design, notably in Southern California
Southern California
Southern California is a megaregion, or megapolitan area, in the southern area of the U.S. state of California. Large urban areas include Greater Los Angeles and Greater San Diego. The urban area stretches along the coast from Ventura through the Southland and Inland Empire to San Diego...
and the surrounding desert
Desert
A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...
states.
Pool recirculation
The final link in the pool recirculation system: skimmer-pump-filter-returns are the water returns. Typically these are referred to as "eyeballs" as they incorporate a swiveling nozzle that can be locked down to point in the desired direction and are reminiscent of a swiveling human eyeball. The directional adjustment is usually a 360 degree radius circle of 45 degrees away from the pool wall. Most home pools would incorporate at least two such "eyeballs".One recent development in skimmers was the 1970s "Aquagenie(TM)" which differers considerably operationally from conventional skimmers—most of which are quite similar in operation, if not appearance—by both drawing the pool water and returning it to the same location through a submerged slot which diverts the water downwards and in a wide fan shape. The concept incorporates a reservoir
Reservoir
A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...
system to contain saturated trichor tablets which the resulting high strength chlorinated water dribbles back into the recirculation system, so it doubles up as a chlorine feeder as well as a normal skimmer. Arguably an "improvement" in skimmer design, patents on the device expired in 2003 and the system is now available from several US manufacturers.
Heaters
Other equipment which may be optioned in the recirculation system include pool water heaters. They can be heatHeat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...
pumps, natural gas or propane gas heater
Gas heater
A gas heater is a device used to heat a room or outdoor area by burning natural gas or liquefied petroleum gas. Indoor household gas heaters can be broadly categorized in one of two ways: flued or non-flued, or vented and unvented...
s, electric heaters, and Solar hot water panel heaters - increasingly used in sustainable design
Sustainable design
Sustainable design is the philosophy of designing physical objects, the built environment, and services to comply with the principles of economic, social, and ecological sustainability.-Intentions:The intention of sustainable design is to "eliminate negative environmental...
of pools.
Other equipment
Diversions to electronic oxidation systems, Ionization systems, microbe disinfectinon with ultra-violet lamp systems, and "Tri-Chlor Feeders" are other auxiliary systems for Swimming pool sanitation; as well as solar panels; are in most cases required to be placed after the filtration equipment, and are the last items before the water is returned to the pool.Equipment enclosure
Most swimming pool installations incorporate an outdoor structure designed to house the pool filtration equipment; as a protective measure against premature deterioration from sunlightSunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...
and rain
Rain
Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...
; and as motor noise-sound insulation for the pool users and neighboring properties. Typically, these structures range in size from a simple flip-lid three-sided sound-insulated box set against a convenient house wall, the lid being constructed on a 15 to 20 degree slope and the interior large enough to hold the filter plant, pump, and whatever chlorination system has been included.
Some structures are, in addition to a separate sound-proofed pool equipment location, a Pool House (Pool Cabana - "Pool Shed") with a bathroom
Bathroom
A bathroom is a room for bathing in containing a bathtub and/or a shower and optionally a toilet, a sink/hand basin/wash basin and possibly also a bidet....
, shower, changing, and storage area; and sometimes a full-size building with an: entertainment and recreation room, a small kitchen, and "guest house" accommodations. Consistent vigilance for the safety of young children in and around the pool, often by a designated adult, is important where social distraction is possible.
Recreation amenities
Features that are part of the water circulation system can extend treatment capacity needs for sizing calculations and can include: artificial streamStream
A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...
s and 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, in-pool 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, integrated 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 spas, water slide
Water slide
A water slide is a type of slide designed for warm-weather or indoor recreational use at water parks. Water slides differ in their riding method and therefore size...
s and sluices, artificial "pebble beaches," submerged seating as bench-ledges or as"stools" at in-pool bars, plunge pool
Plunge pool
A plunge pool can be a natural hydrologic fluvial landform feature or a constructed recreational garden feature...
s, and shallow children's wading pools.
Landscape designers often integrate the pool and its amenities and surrounding decking with the property's garden
Garden
A garden is a planned space, usually outdoors, set aside for the display, cultivation, and enjoyment of plants and other forms of nature. The garden can incorporate both natural and man-made materials. The most common form today is known as a residential garden, but the term garden has...
s and the residence
Residence
The term residence may refer to:* House* Home* Nursing home* Residence in English family law, pertaining to where children should live in the case of disputes* Habitual residence, a civil law term dealing with the status of refugees, and child abduction...
. Outdoor kitchens, barbecue
Barbecue
Barbecue or barbeque , used chiefly in the United States, Canada, the United Kingdom, New Zealand and Australia is a method and apparatus for cooking meat, poultry and occasionally fish with the heat and hot smoke of a fire, smoking wood, or hot coals of...
s and pizza ovens, walkways and patios, plantings, shade structures, garden furniture and outdoor fireplace
Outdoor fireplace
An outdoor fireplace is a place for building fires outside of the home. Similar in construction to an indoor fireplace, an outdoor fireplace is usually added to a stone, brick, or concrete patio. It often consists of a firebox and a chimney. As with indoor fireplaces, an outdoor fireplace...
s, and landscape lighting in the pool and the garden, all can expand the recreational and aesthetic possibilities of a well sanitized sparkling pool.
See also
- Filter (water)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:...
- Waterborne diseasesWaterborne diseasesWaterborne diseases are caused by pathogenic microorganisms which are directly transmitted when contaminated fresh water is consumed. Contaminated fresh water, used in the preparation of food, can be the source of foodborne disease through consumption of the same microorganisms...
- Water purificationWater purificationWater purification is the process of removing undesirable chemicals, materials, and biological contaminants from contaminated water. The goal is to produce water fit for a specific purpose...
- Copper ion swimming pool systemCopper ion swimming pool systemCopper ion swimming pool systems use a low voltage current across copper bars to free copper ions into the flow of pool water to kill organisms such as algae in the water and provide a "residual" in the water. Better systems also use titanium plates to produce oxygen in the water to help degrade...
- Reflecting poolReflecting poolA reflecting pool or reflection pool is a water feature found in gardens, parks, and at memorial sites. It usually consists of a shallow pool of water, undisturbed by fountain jets, for a calm reflective...
- Water gardenWater gardenWater gardens, also known as aquatic gardens, are a type of man-made water feature. A water garden is defined as any interior or exterior landscape or architectural element whose primarily purpose is to house, display, or propagate a particular species or variety of aquatic plant...
- FountainFountainA 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....