The primary aim of the Microbial Safety in swimming water is theprotection of public health. The use of swimming pools and similar recreational waterenvironments – and the resulting social interaction, relaxation and exercise – is associatedwith benefits to health and well being.The hazards that are encountered in swimming pools and similar environments vary from site to site, as does exposure to the hazards. In general, most available information relates to health outcomes arising from exposure through swimming and ingestion of water.
Swimming pools may be supplied with fresh (surface or ground), marine or thermalwater (i.e. from natural hot springs). They may be domestic (private), semi-public (e.g.hotel, school, health club, housing complex, cruise ship) or public (e.g. municipal),and they may be supervised or unsupervised. Swimming pools may be located indoors,outdoors (i.e. open air) or both; they may be heated or unheated. In terms of structure,the conventional pool is often referred to as the main, public or municipal pool.
Where there are high public load and rapid agitation of water, it may become difficult to maintain satisfactory pH,microbial quality and disinfectant concentrations. As users may include:
• the general public;
• children/babies;
• hotel guests;
• tourists;/health club members;
• exercise class members (e.g. aqua-aerobics);
• competitive swimmers;
• non-swimmers;
• clients of outdoor camping parks;
• leisure bathers, including clients of theme parks; and
• specialist sporting users, including scuba divers, canoeists and water polo participants.
Certain groups of users may be more predisposed to hazards than others. For example:
• Children may spend long periods in recreational waters and are more likely than
adults to intentionally or accidentally swallow water.
• The elderly and handicapped may have strength, agility and stamina limitations.
• Immunocompromised individuals may be at higher risk from microbial or
chemical hazards.
A very high rate of water exchange is necessary (even if not completely effective) if there is no other way of preventing microbial contamination, where complete drain-down between users is not possible
Hazard and risk
Popularly, the terms hazard and risk are used interchangeably. Correctly, a hazard is a setof circ*mstances that could lead to harm – harm being injury, illness or loss of life. Therisk of such an event is defined as the probability that it will occur as a result of exposure to a defined quantum of hazard. In simpler terms, hazard is the potential for harm,while risk is the chance that harm will actually occur.Ingestion of, inhalation of or contact with pathogenic bacteria, viruses,fungi and protozoa, which may be present in water and pool surroundingsas a result of faecal contamination, carried by participants or animalsusing the water or naturally present
Microbial Hazards
A variety of microorganisms can be found in swimming pools and similar recreationalwater environments, which may be introduced in a number of ways.In many cases, the risk of illness or infection has been linked to faecal contaminationof the water. Many of the outbreaks related to swimmingpools would have been prevented or reduced if the pool had been well managed.
Non-faecal human shedding (e.g. from vomit, mucus, saliva or skin) in the swimmingpool or similar recreational water environments is a potential source of pathogenicorganisms. Some bacteria, most notably non-faecally-derived bacteria, may accumulate in biofilms and present an infection hazard.
In addition, certain freelivingaquatic bacteria and amoebae can grow in pool, natural spa or hot tub waters,in pool or hot tub components or facilities (including heating, ventilation and air-conditioningsystems) or on other wet surfaces within the facility to a pointat which some of them may cause a variety of respiratory, dermal or central nervoussystem infections or diseases. Outdoor pools may also be subject to microorganismsderived directly from pets and wildlife.
Microbes in Swimming Pools
- 1. Faecally-Derived Microbes
- a. Viruses
- I. Adenoviruses
- II. Hepatitis A
- III. Noroviruses
- Eneteroviruses
- b. Bacteria
- I. Shigella spp.
- II. E.coli 0157
- c. Protozoa
- I. Giardia
- Crytosporidium
- 2. Non-faecally-Derived Microbes
- a. Viruses
- I. Molluscipoxvirus
- II. Papillomavirus
- III. Adenoviruses
- b. Bacteria
- I. Legionella spp.
- II. Pseudomonas spp.
- III. Mycobacterium spp.
- IV. Staphylococcus aureus
- V. Leptospira spp.
- c. Protozoa
- I. NaegleriaFowleri
- II. Acanthamoeba spp.
- III. Plasmodium spp.
- d. Fungi
- I. Trichophyton spp.
- II. Epidermophytonfloccosum
Chemicals use in Swimming Pools
Chemicals found in pool water can be derived from a number of sources: the sourcewater, deliberate additions such as disinfectants and the pool users themselves. While there is clearly a need to ensure proper consideration of health and safetyissues for operators and pool users in relation to the use and storage of swimming poolchemicals
There are three main routes of exposure to chemicals in swimming pools and similarenvironments:
• direct ingestion of water;
• inhalation of volatile or aerosolized solutes; and
• dermal contact and absorption through the skin.
A number of management-derived chemicals are added to pool water in order toachieve the required water quality. A proportion of pool water is constantly undergoingtreatment, which generally includes filtration (often in conjunction with coagulation),pH correction and disinfection
Disinfection
A range of disinfectants are used in swimming pools and similar environments. Themost common are outlined in Table below. They are added in order to inactivate pathogens and other nuisance microorganisms.Chlorine, in one of its various forms, is the most widely used disinfectant.Some disinfectants, such as ozone and UV, kill or inactivate microorganisms asthe water undergoes treatment, but there is no lasting disinfectant effect or ‘residual’that reaches the pool and continues to act upon chemicals and microorganisms in thewater. Therefore, there is a need of disinfectant which can be employed to provide continued disinfection. Chlorine Dioxide can be chosen for its higher residual level in the water.
The type and form of disinfectant need to be chosen with respect to the specific requirementsof the pool. In the case of small and domestic pools, important requirements areeasy handling and ease of use as well as effectiveness. In all cases, the choice of disinfectantmust be made after consideration of the efficacy of a disinfectant under the circ*mstancesof use and the ability to monitor disinfectant levels.
Disinfectants used
most frequently in large,
heavily used poolsDisinfectants used
in smaller pools
and hot tubsDisinfectants used
for small-scale and
domestic poolsChlorine
• Gas
• Calcium/sodium
hypochlorite
• Electrolytic generation
of sodium hypochlorite
• Chlorinated isocyanurates
(generally outdoor pools)
Bromochlorodimethylhydantoin
(BCDMH)
Chlorine Dioxide
Ozonea
UVaBromine
• Liquid bromine
• Sodium bromide +
hypochlorite
Lithium hypochloriteBromide/hypochlorite
UVa
UV–ozonea
Iodine
Hydrogen peroxide/
silver/copper
Biguanide
Table: Disinfectants and disinfecting systems used in swimming pools and similar environments
Chlorine-based disinfectants
Chlorination is the most widely used pool water disinfection method, usually in theform of chlorine gas, sodium, calcium or lithium hypochlorite but also with chlorinatedisocyanurates. These are all loosely referred to as ‘chlorine’.It is recommended that acceptable levelsof free chlorine continue to be set at the local level, but in public and semi-publicpools these should not exceed 3 mg/l (3.0ppm) and in public/semi-public hot tubs these shouldnot exceed 5 mg/l. Lower free chlorine concentrations may be health protective whencombined with other good management practices (e.g. pre-swim showering, effective coagulation and filtration, etc.) or when ozone or UV is also used. But there has been issues regarding with its effectiveness:
- Its efficacy is controversial at higher pH values.
- Chlorine is very temperature sensitive, therefore less effectiveness in temperature un-control pools
- Has colour taste and smell, which is very irritating for the users. Many of reports suggest chlorine sensitivity for certain people, which may result in irritation, skin rashes and many eye problems
- Use at higher dose to achieve the require results
- No standardized chlorine is available in the local market. Therefore efficacy results are dramatically variable
- CT value is much higher, means almost 60-90 min are required to disinfect the pool
- Greater concerns are for its by-products, which include chloramines, Trihalomethanes THMs. These by-products are considered as carcinogenic for the human use, and has been condemned by international agencies for human use
Chlorine dioxide
Chlorine dioxide is not classed as a chlorine-based disinfectant, as it acts in a differentway and does not produce free chlorine. Chlorine dioxide breaks down to chlorite andchlorate, which will remain in solution; the WHO health-based drinking-water provisionalguideline value for chlorite is 0.7 mg/l (0.7ppm) (based on a TDI of 0.03 mg/kg of bodyweight) (WHO, 2004), and this is also the provisional guideline for chlorate.
Chlorine dioxide makes it an ideal choice to meet the microbial and oxidative challenges of today’s environmentally concerned world. It is an ideal replacement for chlorine, providing all of the benefits of chlorine and more, but without any of its weaknesses and detriments. Chlorine dioxide is a broad spectrum biocide with 2.6 times the oxidizing capacity of chlorine. It is a selective oxidizer that is effective across a broad pH range.
Chlorine dioxide is an effective tool for the treatment of pool and recreational water. It is a powerful disinfectant that nicely balances purification performance against disinfection by product formation. It is one of four EPA approved disinfectants for drinking water with CT values second only to ozone in biocidal efficacy but without the ozonation by-products or high capital expense.
Dutrion (Chlorine Dioxide) is manufactured by Dutrion North America Ltd located in Western Canada. Dutrion products comply with the highest regulatory purity standards for drinking and pool water, such as NSF.60 standards. Dutrion are transportable, non-explosive one component tablet, once added to specific volume of water, reacts quickly and safe into long lasting chlorine dioxide solution with a concentration of 0.2%.
Chlorine Dioxide has several advantages over chlorine, bromides and ozone.
• It is more effective as a disinfectant than chlorine in most circ*mstances against water borne pathogenic microbes such as viruses, bacteria and protozoa – including the cysts of Giardia and the oocytes of Cryptosporidium
• Recommended by WHO as safest disinfectant
• Fully operational on pH levels between 4-10
• Temperature independent
• No taste, smell and odour
• Long term residual disinfection effectiveness
• No reaction with ammonia, thus no release of THM recommended for human
• No corrosive effects
• Very flexible in dosing rates and combined disinfection
• No release of free chlorine
• Only limited investment cost
• Does not change the smell, taste and colour of drinking water
• Easy to transport
• NSF certified product
• First time ever in Pakistani market
• Ready to use in powder/tablet (20gm) form
• North American manufactured with all quality and standard certificates, which comply all federal and international regulations
• Very much cost effective.
• Most diseases related with water contamination can be controlled
