Swimming pool sanitation is the process of ensuring healthy conditions in
swimming pools, hot tubs, plunge pools, and similar recreational water venues.
Proper sanitation is needed to maintain the visual clarity of water and to
prevent the transmission of infectious waterborne diseases.
Methods Sanitation methods include a water
filter to remove pollutants, disinfection to kill infectious
microorganisms, swimmer hygiene to minimize the introduction of
contaminants into pool water, and regular testing of pool water, including
chlorine and pH levels. Guidelines
The World Health Organization 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. The main organizations providing certifications for pool and
spa operators and technicians are the National Swimming Pool Foundation and
Association of Pool & Spa Professionals. The certifications are accepted by many
state and local health departments. Contaminants and disease
Swimming pool contaminants 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 harbouring 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-products.
Pathogenic contaminants are of greatest concern in swimming pools as they have
been associated with numerous recreational water illnesses. 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.
The journal Environmental Science & Technology reported that sweat and urine
react with chlorine and produce trichloramine and cyanogen chloride, two
chemicals dangerous to human health. [1] Maintenance and hygiene
Contamination can be minimized by good swimmer hygiene practices such as
showering before and after swimming, not letting children with intestinal
disorders swim. Effective treatments are needed to address contaminants in pool
water because preventing the introduction of pool contaminants,
pathogenic and non-pathogenic, into swimming pools is impossible
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 chloramines, restricting
the formation of disinfection by-products and optimizing sanitation
effectiveness. To kill pathogens and help prevent recreational water
illnesses, pool operators must maintain proper levels of chlorine or another
sanitizer. Over time, calcium from municipal water
tends to accumulate, developing salt deposits in the swimming pool walls and
equipment, reducing their effectiveness. Calcium also absorbs chlorine and
prevents proper performance of added chemicals. Therefore, it is advised to
either completely drain the pool, and refill it with fresh water, or recycle
the existing pool water, using reverse osmosis. The advantage of the latter
method is that 90% of the water can be reutilized
Pool operators must also store and handle cleaning and sanitation chemicals
safely. Prevention of diseases in swimming pools
and spas Disease prevention should be the top
priority for every water quality 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. Modern digital equipment when used in
conjunction with automatic chemical feeders results in stable pH and
chlorine levels. Local jurisdiction may demand a wait time if chemicals are
added by hand to the water so that swimmers are not injured.
Chemical parameters include disinfectant levels according to regulated pesticide
label directions. pH should be kept between 7.2-7.8. Human tears have a pH
of 7.4, making this an ideal point to set a pool. More often than not, it is
improper pH and not the sanitiser that is responsible for irritating swimmers'
skin and eyes. Total alkalinity of 80-120 ppm and
calcium hardness between 200 – 400 ppm. Good hygienic behavior at swimming pools
is also important for reducing health risk factors at swimming pools and spas.
Showering before swimming can reduce introduction of contaminants, and
showering again after swimming will help to remove any.
Those with diarrhea or other gastroenteritis illnesses should not
swim within 2 weeks of an outbreak, especially children. Cryptosporidium is
chlorine resistant. 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 potential,
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 on a regular basis. This process becomes the essence of an
optimum water quality management program.
Systems and disinfection methods = Chlorine and bromine methods=
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 group 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; 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 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 "superchlorinate" the
pool with a high dose of inorganic chlorine sufficient to deliver 10 ppm
chlorine. Regular superchlorination 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 as well as by use of non-chlorine "shock oxidizers" such as
potassium peroxymonosulfate. Medium pressure UV technology is used to
control the level of chloramines on indoor pools. It is also used as a
secondary form of disinfection to address chlorine tolerant pathogens. A
properly sized and maintained UV system should remove the need to shock for
chloramines, although shocking would still be used to address a fecal
accident in the pool. UV will not replace chlorine, but is used to control
the level of chloramines, which are responsible for the odor, irritation,
and enhanced corrosion at an indoor pool.
= Copper ion system= Copper ion 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. Alternative systems also use titanium plates to produce oxygen in the
water to help degrade organic compounds. Private pool filtration
= Water pumps= An electrically operated water pump is
the prime motivator in recirculating the water from the pool. Water is forced
through a filter and then returned to the pool. Using a water pump by itself
is often not sufficient to completely sanitize a pool. 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 and up
to 24 hours in summer. To save electricity costs, most pools run water
pumps for between 6 hours and 12 hours in summer with the pump being controlled
by an electronic timer. Most pool pumps available today
incorporate a small filter basket as the last effort to avoid leaf or hair
contamination reaching the close-tolerance impeller section of the
pump. = Filtration units=
Sand A pressure-fed sand filter is typically
placed in line immediately after the water pump. The filter typically
contains a media such as graded sand to 24 to the inch). A pressure fed sand
filter 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
[7.48 US or 6.23 UK gallons]. 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 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 earth to
help filter out contaminants. Commonly referred to as 'D.E.' filters, they
exhibit superior filtration capabilities. Often a D.E. filter will
trap waterborne 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 filter area arranged in a tightly packed 12"
diameter x 24" long 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 sewer connection. They are popular where backwashed water from
a sand filter is not allowed to be discharged or goes into the aquifer.
Automated pool cleaners Automated pool cleaners more commonly
known as "Automatic pool cleaners" and in particular electric, robotic pool
cleaners provide an extra measure of filtration, and in fact like the
handheld vacuums can microfilter a pool, which a sand filter without flocculation
or coagulalents is unable to accomplish 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 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 article will indicate.
= Skimmers= Coping apertures
Water is typically drawn from the pool via a rectangular aperture in the wall
connected through to a device fitted into one 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. If the pool's water pump is
operational water is drawn from the pool over a floating hinged weir, and down
into a removable "skimmer basket", the purpose of which is to entrap leaves,
dead insects and other larger 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. 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. = Pool recirculation=
The final link in the pool recirculation system: 'skimmer-pump-filter-returns'
are the water returns. Heaters
Other equipment which may be optioned in the recirculation system include pool
water heaters. They can be heat pumps, natural gas or propane gas heaters,
electric heaters, wood burning heaters, or Solar hot water panel heaters -
increasingly used in the sustainable design 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. Other features
= Recreation amenities= Features that are part of the water
circulation system can extend treatment capacity needs for sizing calculations
and can include: artificial streams and waterfalls, in-pool fountains,
integrated hot tubs and spas, water slides and sluices, artificial "pebble
beaches," submerged seating as bench-ledges or as"stools" at in-pool
bars, plunge pools, and shallow children's wading pools.
See also Copper ion swimming pool system
Fountain Reflecting pool
Water garden Water purification
References External links
ICS 13.060.01 Water quality in general - A series of ISO standards
ICS 07.100.20 Microbiology of water