water quality management of swimming pool.pdf

8/20/2019 Water Quality Management of Swimming Pool.pdf

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INDIAN PLUMBING TODAY COVER STORY

DECEMBER 2012 14

Water Quality Management

of Swimming Pools


DECEMBER 2012 14

INTRODUCTIONA growing number of people throughout the world use Swimming pools. India is no exception.Exponentially increasing population, changing lifestyles, rising health consciousness andbetter incomes have given rise to a large swimming pool industry. These days swimmingpools are finding a place in:

• Residences (Single homes/ Apartments/ Villas/ Townships)• Educational institutions• Sports complexes• Spas• Water Parks• Special pools for physically challenged• Pools for Animals(Equine/ Dolphin)• Diving pools

to name a few.

Consequent to unchecked pollution, natural water bodies such as Village ponds, Lakes andRivers are fast losing their appeal as places where one could swim safely. As a result evenfarmhouses with natural water bodies in them tend to have modern swimming pools thesedays as a common feature.

Prof. Rajendrakumar V. Saraf


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A swimming pool is no longer just a piece ofarchitecture. It involves various techniques andrequires a multi-disciplinary approach for acomprehensive design. There are many ways ofdesigning a swimming pool and the Pool industryoffers many schemes to meet most situations forthe investor’s benefit. Swimming pool designers,contractors and operators have preferences orprejudices for one system or another. Whileaesthetics and pool sizing can be dependent onindividual requirements, site characteristics andeconomics; safety considerations will have to beof the highest priority without any compromises.

A Swimming Pool is either rectangular or of anyfree shape. Free shape tanks are generally usedfor resort and leisure pool complexes. Generally,rectangular tanks are preferred for learners and

purposes of competitions.

A tank is normally constructed in either RCC orbrickwork. After water proofing, glazed ceramictiles or glass tiles are fixed on the inner surface ofthe tank.

Dimension of poolThe dimensions for the pool are based on theCage of Safety for the appropriate category ofdiving. The Cage of Safety is a body of waterwithin the pool into which it is safe to dive from

the deck or the diving board. The profile of a poolmay be of any shape or size provided it containsminimum dimension of the Cage of Safety. Basicrequirements for pool dimensions depend on itstype and usage.

WATER IN SWIMMING POOLWater is the most important part of a swimmingpool. Earlier practice was to fill it with freshwater and use until such time the water wasvisibly dirty. The pool was then drained andrefilled with fresh water. Each swimmerentering the pool contaminates water withmicrobes, inorganic and organic compounds,sweat, saliva, perspiration, cosmetics, andexcretory products of the body. Further, dust,leaves and flowers from the surroundingenvironment pollute pool water. This makeswater unsafe and turbid, as it promotesmicrobial and algal growth rapidly. Infectionof many water borne diseases due to watercontamination in poorly operated swimmingpool cannot be ruled out. Since the entire body

of the swimmer comes in contact with water,water quality in the swimming pool is mostimportant from the health aspect and has to beconsidered during designing and installing ofthe swimming pool. Consequently, filtrationsystems with recirculation were introducedto continue using the same water for longerperiods. Water in a pool is filtered, disinfected,and recycled to accepted pool water standards.Only make up water is added to compensatewater loss due to evaporation, suction sweepingof pool and backwashing of filter.

Therefore, it is essential to have an efficientdesign of water circulation, and treatment systemincorporating disinfection of water.

WATER CIRCULATION IN POOL

Contaminated water along with floating scumand solids overflows from the pool and is led tothe filtration system. There are different typesof overflow systems. Water is also drawn fromthe bottom of the pool at the deepest point.Overflow of the water plays an importantrole in maintaining water quality in the pool.Some of the typical overflows from the pool areshown in Figure-1. Overflowing water from thepool either goes to the balancing tank or to thebucket strainer. Leaves and hair are trappedin the strainer. Water from balancing tank or

strainer is pumped to the Pressure Sand Filter.Suspended solids and turbidity are removedin the filter. Filtered water is disinfected andreturned to the pool. Fully treated water entersthe pool through the nozzles at bottom or insidewalls. Inlet and outlet of water in the poolare to be designed to ensure that the filtereddisinfected water replaces water at any cornerin a designed turnover time. Typical waterfiltration and circulation system for water areshown in Figure-2.


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Turnover TimePool becomes polluted at different ratesdepending on the usage and swimmers.

Generally, water becomes turbid very fast atshallow depth because more people wash offmore dirt in less amount of water. An old andpractical guide to decide the capacity of thefilter is to reduce one hour from the pool’sturnover time for each foot depth of water.Now, turnover time is decided on the basis ofdust loading. It varies from 10 hour for verylight loading in deep water to 10 minutes forextreme loading to beach shallow all withinthe same pool. To maintain the desired qualityof water in the pool, total volume of water inthe pool shall be passed through the filter andcirculated in given time called as turnover time.It is defined as below:

Total Volume of Water in Pool (cu.m.)Turnover time (hr) = ---------------------------------- Filtration Rate cu.m./hr

Selection of the correct turnover time for thepool will guarantee the design, water clarity

and quality even at peak bathing loads. Generalrecommended turnover time in hours for differentpools is as below:

• Paddling or intensive learner, shallow pools 1• Teaching & Play pools 2• Public & Hotels with intensive use 3• School, Olympic/International Competition 4• Community 5• Clubs and Private intensive usage 6• Residential pool 7• Diving Deep side, light & private usage 8

Filtration SystemThe filter deals with particulate matter. It strainsout suspended solids to sub-micron size tomaintain clarity of water. It neither removesdissolved solids nor deals with micro-organisms.Filtration combined with disinfection keepswater:

• Clear and non-toxic• Odourless and tasteless• Free of bacteria and algae• Balanced to prevent corrosion and scale

formation


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The working capacity of a filter is the amountof dirt it can hold without blocking or passingmore than, say 10-micron size particle in a giventime. The rate of filtration is the flow of waterthat passes through the filter to achieve specifieddegree of clarification in a given turnover time.Due consideration shall be given to the followingfactors that influence filtration such as:

• High bathing loads• Heating of pool water• Covering the pool• Blown algae and dust falling on the surface of pool• Mineral found in water itself

Generally, pressure sand filters of medium (25cu.m./sq.m./hr) and high (50 cu.m./sq.m./hr) loading rate are used. Other filters, such

as Cartridge filter, Pre-coat filter and VacuumDiatomaceous filter are also used. Variousswimming pool filter manufacturers claim thefiltration rate for their filter models. However, itis commonly observed that these rates are not onrealistic grounds, therefore causes malfunctioningof the pool system.

Other Pool Cleaning EquipmentsOnce heavy dust and the dead algae settle downon the bottom of the pool, it cannot be removedby filtration. Therefore, a device called asSuction Sweeper is used. It has a Suction Headprovided with a brush and a Vacuum/SuctionHose. The Suction Sweeper pumps water alongwith dust out of the pool. Water is either wastedor recycled to the filter. Nylon brushes are alsoused to clean and scrub off the algal growth onthe tiles.

DISINFECTIONOnce a swimmer enters the pool, his/her entirebody gets in contact with pool water. Therefore,pool water must be as good as, if not better thanthe water we drink. It has to be clearer thandrinking water and should have a palatable

disinfectant. Water shall always stay fresh eventhough every swimmer is adding contaminantsrepeatedly and adding to bacterial pollution.Each bather can introduce about 600 millionmicrobes at first plunge. Followings areessential requirements for disinfectant for thepool:


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• Shall be potent enough to destroy micro-

organisms rapidly to prevent transmissionfrom one swimmer to another

• Adequate disinfectant residual in the water atall times

• Shall be nontoxic to swimmer without any toxicbyproducts

• Shall not contribute bad taste/odour• Shall not accumulate in pool to reach to the

harmful level

A satisfactory disinfection system with efficientfiltration stops infection; prevents algae formation;

eliminates taste and odours; controls scaling andcorrosion in water; makes water crystal clear; givessparkling appearance; and keeps the pool alwayssafe for the swimmer. Different disinfectantproducts and systems are available in the marketand can be categorized as below:

• Chlorine gas and chlorine compounds• Halogen other than chlorine• Ozonization• Metal ion generators• Alternative disinfection systems and chemicals

1. ChlorinationChlorine can be introduced to swimming poolwater by the use of the following:

• Chlorine Gas• Sodium Hypochlorite solution• Calcium Hypochlorite powder• Lithium Hypochlorite granules/tablets• Chloroisocyanurate granules/tablets• Electrolytic Hypochlorite generators

Action of Chlorine as disinfectantWhen chlorine is added to pool water, the followingreactions take place:

• Neutralises the pollutants present in the poolwater

• Reacts with sunlight, heat and agitation• Combines with nitrogenous impurities to form

chloramines (Combined Chlorine)• Remains as residual chlorine for disinfection

and algae control over a design period.

The Residual Chlorine in water can be measured asfree, combined and total chlorine. It plays a majorrole in eliminating the chances of transmittinginfection to fellow swimmer. Free Chlorine isa strong disinfectant, almost odourless andimmediately kills micro-organisms. Combined

Chlorine is a poor disinfectant, has pungent smelland causes irritation to eyes and takes few hoursto act. As guidelines, Free Residual Chlorineshould be three times more than the CombinedResidual Chlorine. It ensures immediate actionand a long-lasting action for safe water. It alsoovercomes eye irritation, odour and algal growth.The practice of break point or super-chlorinationto the level of 5 mg/l, Residual Chlorine destroyschloramines and reduces the Combined Chlorinelevel.

Residual Chlorine exists in water, mainly asHypochlorous acid (HOCl) and less effectiveHypochlorite (OCl) ions. Action of disinfectantions depends on the pH level. For example, evenmild acid pH (6.5) will speed up the disinfectionprocess and also corrosion. Too alkaline pH (morethan 7.5) will nullify compound properties andincrease dosing rates just to deal with ordinarycontamination. Most favourable pH is mildalkaline (7.1-7.3) above the neutral.

A comparison of three forms of Chlorine i.e.Chlorine gas, liquid Chlorine and dry Chlorine isgiven in the Table-1:

Dry Chlorine - Lithium HypochloriteIt is granulated bleaching powder, packed inbags, having 30% available Chlorine and pH7-8. It is totally soluble in water. It is safe, can beeasily stored and handled, and can be added topool directly. It is more expensive and not easilyavailable in India. It adds 65% of binder to pooltotal dissolved solids.


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Details Chlorine Gas Liquid Chlorine Dry Chlorine

Technical Name Chlorine Sodium Hypochlorite CalciumHypochlorite

Physical &chemicalProperties

Green, pungent gas.2.5 times heavier than air.pH: Acidic

LiquidAlkaline. pH:12-13

Dry powder.pH: 11-12

Storage Liquefied gas in cylinder(100 kg). Long shelf life

Liquid stored in cans, shortshelf life

Powder stored in bags. Longshelf life if packed properly

AvailableChlorine

100% 5 to 10%. Rest is alkali andwater.

30 to 70%. Rest is eitherinsoluble or soluble Calcium salts

DisinfectionPower

Highly effective It disperses easily and actsrapidly

Very effective disinfectant

Feeding Device Requires failsafe,sophisticated feeding

(Vacuum Feed/PressureFeed) arrangements

By gravity or through simpledosing pump.

Flow can be immediatelymeasured and dozing can beproportionate to water flow.

It is partly soluble in water andcannot be dozed directly to

pool. As a general practice, itis dispersed in water and clearsuperant is dozed.

Handling/ Risks Dangerous if not handledproperly. Requires specialstorage facilities and strin-gent precautions. No morerecommended in west onsafety grounds.

Requires careful handling andhighly dangerous if cross-contaminated with acid

Safe to handle. Generates dustwhen dry and sludge whenwet. It is a strong oxidizingagent with potential safetyhazards, highly combustiblewith oil, sawdust, organicmaterials and solvents, etc.

Manpower Trained manpower tohandle dozing devices andemergency situation causeddue to Chlorine leakage

Semi-skilled Semi-skilled

Additionalchemicals to beadded

Soda ash to maintainalkalinity

Hydrochloric Acid to adjust pH Hydrochloric Acid to adjustpH

Side effects Wet Chlorine is corrosivefor all metals. Lowers pHof water due to acid forma-tion.Increases Chloridelevel. Burns eyes and skin.Bleaches costumes if addedin high concentration into

pool water

Increase in pH, total dissol-vent, and chlorides. Acid is tobe added to adjust the pH toneutral. Chloride accumulationneeds careful inspection.

In hard water, it causes pre-cipitates and deposits on poolwalls and scale formation inpipelines. It may clog filter,feeder or cloud hard waters.

Application All types of water and pool Medium and smaller pools.In hard water it causes pre-cipitates and deposits on poolwalls.

Very good for soft water. Inhard water, causes precipitatesand deposits on pool walls.

Cost Lowest cost per kg of Chlo-rine and disinfectant

Costlier than Chlorine gas, hasoverall high performance costand requires efficient and guar-anteed supply services.

Economical

Table-1 : Comparison of different forms of Chlorine


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ChlorocyanuratesCyanuric acid is used to reduce Chlorine lossin the outdoor pools. Cyanuric acid shieldsdecomposition of Hypochlorous Acid from ultra-violet light. It facilitates the presence of chlorinein water for longer duration. Recommended dozesare from 25 to 100 PPM maximum. Cyanuric acidis a powder having pH 3-5. To be effective, a levelof 30-mg/l cyanuric acid should be maintained inwater. Handling of Cyanuric acid is difficult dueto its pungent smell and irritation to eyes. Its use isnot yet popular in India. Cyanuric Acid combineswith Chlorine to form following compoundscalled Cyanurates Chlorine.

Sodium dichloroc- – Stabilized powder oryanurate & Potassium granules 60% availabledichlorocyanurate chlorine, pH 6-7,

effective, self stabilizingdisinfectant readily &completely soluble

Sodium trichlorois- – Stabilized powder ocyanuric acid or tablet,

90% available chlorine

Chloroisocynurates provide their own CyanuricAcid. When these compounds are used asdisinfectants, the level of Cyanuric Acid in thepool water should not be normally allowed

to exceed 200 mg/l, however in exceptionalcircumstances, it may be allowed to rise to400 mg/l. Pool can be operated with higherfree Chlorine residual (2 mg/l). It should beincreased to at least 2.5 mg/l when CyanuricAcid level exceeds 100 mg/l.

Chloroisocynurates are very effective; readily andcompletely soluble; and self-stabilizing agents.They have long storage life; can be convenientlyhandled; powerful and ideal in bright sunlight;also very effective in hard water. There is noneed of a feeding device, as it can be addeddirectly to the pool. Chloroisocynurates are moreexpensive, and slow down kill rate of Chlorine.Dozing continually raises Cyanuric Acid level.They are incompatible with any contaminationor any other Chlorine. Further, periodic superchlorination of pool water is required. Binderpresence can cause algal bloom and slow downdestruction. It is highly susceptible to hazardouscontamination in store. Due to slow action, algaemay grow in the pool.

Electrolytic ChlorinationIn the Electrolyzer, current is passed through theanode and cathode in the salt solution, which is agood conductor of electricity, thus electrolyzing thesalt solution. This results in Chlorine (Cl) gas beingproduced at the anode, while Sodium Hydroxide(NaOH) and Hydrogen (H2) gas are produced atthe cathode. The Chlorine further reacts with theHydroxide to form Sodium Hypochlorite (NaOCl).The solution generated has a pH value between8 to 8.5, and a maximum equivalent Chlorineconcentration of less than 8 g/l. It has very longshelf life which makes it suitable for storage. Usingonsite Sodium Hypochlorite generator, 4.5 kg ofsalt and 4 KWH of power are required to produce1kg equivalent of chlorine. Hydrogen gas mustbe vented suitably and safely to the atmosphereoutside the building. It is most suitable for stable

bathing loads. Electrodes last for 2 to 3 years.

2. Halogens Other than Chlorine(a) BromineBromine is also a member of the halogen group ofelement and its reactions in pool water are almostsimilar to that of Chlorine. Both free Bromine asHypobromous Acid and the combined forms asBromamines are effective bactericides, viricides,algaecides and oxidizers of organic matter.Unlike Chlorine and Chloramines, free Bromineand Bromamine cannot co-exist other than

momentarily so only small combined residualis necessary for a strong disinfecting property.Breakpoint reaction with Bromine at pool waterpH levels (7.3-7.8) reaches almost instantaneouslyin the presence of even slight excess of Bromine.Bromination offers faster kill rates and fewer sideeffects. Residual remains longer and is dissipatedslower by sunlight. Bromination is very effectiveat pH 7.8. A pH adjustment is required but toa less extent. Bromamines are not as irritatingas chloramines. Even at 1-2 ppm, brominationodours are not greatly noticeable. Bromine isan excellent algaecide and a 3-ppm super doseinvariably helps in eliminating algae growth.Generally, the side effects are not as difficult tocontrol as for Chlorine. It makes brominationmore economical than chlorine. Besides,dispensing systems are not under pressure likeChlorine gas, so liquid bromination is less likelyto be a ventilation hazard. Due to difficulty inavailability of liquid and dry Bromine in India,bromination is not yet practised in India. LiquidBromine and Bromochlorodimethylhydantoin


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tablets in dry form are used for Bromine treatmentof pool water.

Liquid Bromine : Water is bubbled throughBromine liquid for dozing. Equipment is relativelyeconomical and simpler to operate. It is nasty tohandle and as obnoxious as Chlorine, similar riskto operator and bather from dangerous fumes. Itattacks all metal, therefore it is stored in glass, glassreinforced plastic or plastics fail safe containers.

Dry Bromine Tablet : It is safer and moreconvenient but still more expensive and not yetwidely available. Bromine residual in the range of2-4 mg/l for private pool and 4-6 mg/l for publicpool shall be maintained. Dimethylhydantoinremains in water after the treatment. TheDepartment of Environment recommends that the

level of dimethylhydantoin should not exceed 200mg/l. (1).

(b) IodineIt is stable and safe to handle, and can beeasily stored. It can be dispensed into poolwater easily and economically. Iodamines arenot formed and algaecide support is required.Most modern algaecide are incompetent withiodine, therefore intermittent super chlorinationis necessary. Iodine ion is not an effectivebactericide. It doesn’t contribute taste or odour

to pool water and, therefore doesn’t cause eyeirritation. However, iodine ion can be convertedinto molecular iodine with chlorine and can bereused for several times.

It attacks most of the metal, but other sidereactions are less than the chlorine. Greenish tintis noticeable between 2-5 ppm at pH 7.5. Difficultycan be experienced in maintaining the requiredand total concentration. Not popularly used inabroad and not at all in India.

3. OzoneOzone gas is manufactured by an expensivesophisticated system. It is unstable and anallotropic form of oxygen, where third atomreadily detaches to become a powerful oxidizingagent. It is 10 to 20 times more powerful thanchlorine to inactivate bacteria, viruses, cysts andspores, removes colour, taste and smell. It is fastacting, very effective, non selective and does notproduce unwanted byproducts common withother oxidants. A slight excess of ozone in pool

water produces a redox potential + 800 V @ pH7.5 and destroys bacteria within few seconds.Since ozone has short half-life and decomposesrapidly, it must be generated at site by the ozonegenerators.

Ozone is dozed to the pool either directly to thecirculation system or into small portion of waterpassing through a circulation system. Ozonizationof water is without and with deozonization system.In the first system, ozone is dozed in such a waythat the level of ozone remaining in the water,when re-entering the pool, does not exceed 0.05mg/l. In the second system, 0.8 to 1.0 mg/l ozoneis dosed into the water and a contact period of 1to 2 minutes is provided. After the contact period,ozone is completely removed by passing waterthrough deozonizing medium (activated carbon)before returning to pool. To ensure residualdisinfectant in pool water, ozone has to be usedin conjunction with chlorine. Normally 0.2 to 0.3ppm chlorine with marginal hypochlorination issufficient because all oxidizable organic matter isalready been oxidized.

Ozone is a dangerous chemical in the air andhighly corrosive to metals. Approximately 1ppm of ozone induces headache and tightness in


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the chest. To a more graving situation, 20 ppmnearly kills. Discharge tubes must be kept efficientto prevent runaway cost of ozone production.Ozonator system should include safety alarmsto operate at 0.1 ppm. Continuous dry airflowensures quick removal of ozone and preventsany moisture build up in the pool’s humidatmosphere. An Ozonator is costly and takesmajor share of the pool cost. Further, addition ofdeozonization system plus chlorine dozing andcontrolling system exaggerates the costing ofozonator. It is yet to become popular for Indianswimming pool.

4. Metal Ion GeneratorsMetal Ion Generators are electrolytic devicesinstalled into the pool circulation system. Thesedevices introduce silver and copper ions into the

pool water. Silver and copper ions are knownfor bactericidal effect. There are number of suchsystems available in the market, which are basedon the same principle, however their designand practical conditions vary. For example,certain but not all generators are used withsecondary form of disinfectant such as chlorine.It makes it difficult to standardize operation ofa metal generator. For Indian pools, secondarydisinfectant is must to counteract heavy organicload in the pool.

5. Alternative Disinfection Systems & Chemicals(a) Ultraviolet LightUltraviolet light is a potent disinfectant toensure 100% sterilization. UV lamps can beplaced with 100 mm of maximum water flowdepth. Also, fast turnover is must. It does notprovide any residual disinfectant and does notoxidize organic matter in pool. Therefore, it isto be used only in conjunction with secondarydisinfectant that shall be maintained always atthe desired level. Initial cost of equipment ishigh and operation cost is low. It may be suitableonly for small family pool.

(b) Organic BiocidesOrganic biocide is a synthetic organic microbiocideand algaecide, safe and stable; offers long-termresidual, clear, tasteless and non-odourous, non-bleaching and neutral pH. It is incompatible withchlorine, therefore chlorine is to be removed andpH is to be adjusted to 7.5 before its application.Recommended dose varies from 10 to 50 ppm. Itfails to produce crystal clear bright water. Water

may become greenish when pH is not neutral.They do not have oxidizing properties andtherefore are normally to be used along with anoxidizing agent.

(c) Chlorine DioxideSoluble chlorine dioxide is produced byautomatically drawing solution of sodium chloriteand hydrochloric acid solution from two differentcontainers by the following reaction:

5NaClO2+ 4HCl = 4ClO2+ 5NaCl + 2H2O

Often some chlorine is produced. It has no taste,no smell, offers no eye or skin irritation, can beeasily and safely used. A minimum of 0.1 ppmresidual is required with 0.3 acceptable. A trainedpersonnel is required to operate.

There are many alternatives tried for disinfection.However, chlorine and its compounds are used inmost of the swimming pools for its cost, availabilityand simplicity.

Algae ControlAlgae growth is most undesirable in pool dueto safety risks, aesthetic look and also as itimparts bad taste and odour to the pool water.Following are the common forms of algae in thepool water :

a. Suspended growth - pool water is greenish ormilky and causes chocking of filter thatultimately needs more backwashing

b. Attached growth on to the wall - making poolsurface slippery and ugly

c. Black algae patches firmly attached to the poolwall (especially it grows between the joints ofthe tiles) as a result of symbiotic relationship ofalgae with fungi.

Algae contain chlorophyll and other pigmentsto make use of solar energy, and need nitrogen,carbon hydrogen, oxygen and sunlight for growthin pool water. Algae spores exist in the air all thetime. A low pH is conducive to algae growth, anda rising pH indicates that algae are growing fast inpool. Pool water becomes greenish and clarity ofwater diminishes. There are many causes for algalbloom in pool water; some of them can be listed asbelow to understand means of algal control.


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a. Intense sun light and warm weatherb. Poor filtration and longer turnover timec. Poor water circulation causing dead spots in

the pool where disinfectant level is zerod. Inadequate disinfectante. Addition of nitrogen and organic impurities by bathers and surrounding environment, and

from chemical compound binders present insome of the disinfectants

Proper disinfectant level, monitoring pool waterquality, regular backwashing of filter, runningthe filter for given turnover time, regular suctionsweeping, cleaning of pool walls and betterhygienic conditions etc., are preventive measuresto avoid algal growth in pool. Intermittentsuper-chlorination or addition of oxidizingagent removes or breaks down nitrogenous and

organic impurities that deny ever present algaethe opportunity to thrive. Shock chlorinationdeters quite severe attack however for black algaeit may require large quantity of chlorine andblocks the filter due to dead organism. Coppersulphate wipes out algae but causes black stains.Mercury compounds are active but accumulatedangerously. Quats are excellent to control but thedose excess than 50 ppm causes froth and foamin the pool water. Many synthetic algaecides areavailable in the market. However care has to betaken in the selection of algaecide and its doses

to ensure that there is no adverse and toxicityeffect on the swimmer. It is always better to avoid

usage of these unknown chemicals. Strict controland vigilance is must to avoid algal growth in thepool, otherwise in a severe algal bloom, pool is tobe emptied, cleaned and refilled again with freshwater.

Pool Water QualityPool water quality is defined by physical,chemical, bacteriological and biological standards.Specifications of Indian Standards and SPATA forswimming pool water are given in Table-1. Themaintenance of these standards is very essentialto ensure health and comfort of bathers, and tominimize the risk to cause damage to the poolfittings and the equipments. Parameters like pH,clarity, alkalinity, hardness and desired dosesof disinfectant etc play important role to get thedesired quality of water.

Operation & MaintenanceNo matter how beautiful the shape of a pool, thetype of system selected and whether manually orautomatically operated, water quality of a poolis finally decided by the pool operator. Only atrained and qualified pool operator shall operatethe pool. However, it is not normally so. Often, theoperator adds chemicals to the pool water withouthaving understood the chemical characteristicsand the after effects. For example, to control thealgae and to have blue tint to the water, a dose of

copper sulfate to the level of 10 ppm is added tothe pool, which is toxic if ingested.

Table 1 : Quality Standards for Water Quality for Swimming Pool

Sr. No. Characteristic IS: 3328-1965 (2) SPATA 1990 (3)

i) Ph 7.5 to 8.5 7.2 to 7.8

ii) Total alkalinity (as CaCO3), mg/l 50 to 500 100 to 200

iii) Aluminum (as Al), mg/l, Max 0.1 -

iv) Total residual chlorine, mg/l(a) At inlet(b) At outlet

0.5 Max0.2 Max

0.5-2.0(Depends on type of

disinfectant used)

v) Oxygen absorbed in 4 hour at 27 oC, mg/l, Max 1.0 - vi) Total hardness - 50 to 500

vii) Sulphate - Less than 400

viii) Bacteriological(a) Standard plate count(b) Coliform organisms, MPN index

> 200/ml>10/100 ml

>100/mlNil

ix) Clarity Clear & colourless Deepest part shall beclearly visible, free from

suspended matter

x) Odour Absent Absent


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IPT

ConclusionSwimming pool is not a simple water tank to befilled with water. In designing a pool, problemsassociated with water must be clearly understood.A proper water circulation system to eliminatedead spots in the pool, correct turnover time, righttype of filtration system and the most suitabledisinfectant and its adequate dose, regularmonitoring of water quality can assure sparkling,crystal clear and safer than drinking water inswimming pool. The system shall be always user-friendly. The operator should know the preventiveand control measures.

References1. The Treatment & Quality of Swimming Pool Water,

Department of Environment, National Water Council, U.K.2. Indian Standards Quality Tolerance for Water For Swimming

Pool, Bureau of Indian

3. SPATA Standards for Swimming Pool Vol. & Vol. 2,Swimming Pool & Allied Trade Association Ltd, U.K.

4. SPATA Standards for Swimming Pools Water & Chemicals,Swimming Pool & Allied Trade Association Ltd, U.K.

5. John Daves, Handbook Design & Planning of SwimmingPool, The Institute of Swimming Pool Engineers, U.K.

Editorial Note: The Indian Plumbing Association (IPA)and the International Association of Plumbing and

Mechanical Officials India (IAPMO- I) have jointly published the Uniform Swimming Pool Code – India 2011which may be referred to for additional information onSwimming Pool Designs.

Prof. R. V. Saraf is the Founder Chairman of VirajEnvirozing India Pvt. Ltd., a Pune-based companyproviding one window solution to environment. Hehas done M.Sc. in Biochemistry; AMIE in ChemicalEngineering; and M.Sc. in Environmental ControlEngineering & Resource Utilisation from UK.

He has 40 years of experience with more than 1000 successful projects to hiscredit, including 300 swimming pools. He is a Life Fellow of the Institution ofEngineers India and a Life Member of Indian Association of EnvironmentalManagement. He can be contacted at [email protected]

water quality management of swimming pool.pdf

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