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Guide to Hygiene and Sanitation in Aviation. 3rd edition. Geneva: World Health Organization; 2009.

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Guide to Hygiene and Sanitation in Aviation. 3rd edition.

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2WATER

2.1. Background

Travel can facilitate the transfer of communicable disease. The volume and rapidity of travel can have an international impact on disease. This is particularly true for aircraft, as the global span of the aviation industry requires the loading and rapid transport of people and supplies from many locations all over the world. With the 21st-century potential for millions of people to have access to air travel on a global scale come the added problems encountered by aircraft operators that transit both into and out of disease-affected areas or areas with variable and sometimes inadequate standards of general hygiene and sanitation.

One risk is posed by the potential for microbial contamination of aircraft water by animal or human excreta. This contamination may originate from source waters or may occur during transfer operations or while water is stored on board the aircraft. Waterborne disease burdens in many parts of the world include cholera, enteric fevers (Salmonella), bacilliary and amoebic dysentery and other enteric infections. These diseases are not unique to water; food may actually be the dominant risk vector in some environments, and, in fact, most airlines have a good record with respect to known contamination incidents. However, any location is at risk if proper procedures and sanitation practices are not continuously followed to ensure the safety of water that is used for drinking and food processing and preparation.

2.1.1. Water supply and transfer chain

Even if the water at the airport is safe, that does not ensure that it will remain safe during the transfer to the aircraft and storage activities that follow. An understanding of the aircraft drinking-water supply and transfer chain will help to illustrate the points at which the water can become contaminated en route to the tap on board the aircraft.

Generally, the aircraft drinking-water supply and transfer chain consists of four major components:

  1. the source of water coming into the airport;
  2. the airport water system, which includes the on-site distribution system. It may also include treatment facilities if the airport produces its own potable water;
  3. the transfer point (sometimes referred to as the watering point), including the water transfer and delivery system. It is typically a temporary interconnection between the hard-plumbed distribution system of the airport (e.g. at a hydrant) and the aircraft water system, by means of potable water vehicles and carts, refillable containers or hoses. This water transfer process provides multiple opportunities for the introduction of contaminants into the drinking-water;
  4. the aircraft water system, which includes the water service panel, the filler neck of the aircraft finished water storage tank and all finished water storage tanks, including refillable containers/urns, piping, treatment equipment and plumbing fixtures within the aircraft that supply water to passengers or crew.

Figure 2.1 is a flow diagram of a typical aircraft potable water supply and transfer chain. It depicts the water path from potable water source to the aircraft's galley and lavatory taps serving passengers and crew.

Figure 2.1. Aircraft potable water supply and transfer chain.

Figure 2.1

Aircraft potable water supply and transfer chain.

2.1.2. Water requirements

The water storage capacity required for all purposes on board aircraft is based on the number of occupants (passengers and crew) and the duration of the flight, while being limited by weight, aircraft design and other practical considerations.

In practice, the capacity of aircraft water systems varies considerably. Examples of the potable water carrying capacities of different aircraft are given in Table 2.1.

Table 2.1. Approximate capacity of potable water tanks on select aircraft.

Table 2.1

Approximate capacity of potable water tanks on select aircraft.

2.1.3. Health risks associated with water on aircraft

2.1.3.1. Water quality

The importance of drinking-water as a vehicle for the transmission of infectious disease microorganisms in water supplies has been well documented in public and private water supplies.

The WHO Guidelines for Drinking-water Quality (WHO, 2004) (GDWQ) identify the broad spectrum of contaminants, including microorganisms, inorganic and synthetic organic chemicals, disinfection by-products and radionuclides, that can reach hazardous concentrations in potable water supplies and describe systematic approaches to risk management. As a general definition, safe drinking-water, as defined by the GDWQ, does not represent any significant risk to health over a lifetime of consumption, including different sensitivities that may occur between life stages.

The WHO Guidelines for Drinking-water Quality (GDWQ) (WHO, 2004) provide comprehensive guidance to ensure the quality and safety of drinking-water. Most of the concerns involving the safety of drinking-water on board aircraft focus on acute risks because of the short-term and limited exposure conditions. Thus, microbial risks are the principal concerns, although a few risks associated with acutely toxic chemicals also exist.

Significant microbial risks are associated with ingestion of water that is contaminated with human and animal excreta, although exposure through food preparation and direct human contact are probably more significant contributors to overall microbial disease risks.

Studies that highlight the aircraft water safety concern have been conducted by the United States Environmental Protection Agency (USEPA), Health Canada and the United Kingdom's Association of Port Health Authorities (APHA) (see Box 2.1). Total coliforms, Escherichia coli, Pseudomonas aeruginosa, enterococci and clostridia were detected in one or more studies. Most total coliforms are not pathogens per se, but a positive test is an indicator of inadequate sanitation practices; E. coli are indicative of recent faecal contamination, and some E. coli are human pathogens; P. aeruginosa are considered to be opportunistic pathogens, particularly from external contact with, for example, open wounds; enterococci are found in the intestines of warm-blooded animals, so they are indicators of faecal contamination; and Clostridium bacteria are found in the intestines of some humans and, more so, in dogs, which again points to faecal contamination (WHO, 2004).

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Box 2.1

Studies on aircraft water safety. Random testing of water on aircraft by Health Canada in June 2006 found that 15.1% of the aircraft tested positive for total coliform bacteria and 1.2% tested positive for E. coli. Most contamination was found in water (more...)

There are no known reports of illness associated with drinking contaminated water on aircraft. Nevertheless, the potential for serious illness exists, particularly for those with compromised health (e.g. individuals with chronic illness).

The water quality guidelines directly applicable to water on aircraft focus on acute risks from contamination that may be incurred during transfer from the airport, through the transfer point or on board the aircraft. The focus on acute risks is because the exposure that would occur during a flight and be experienced by passengers and crew would be intermittent and of short duration (hours) rather than long term or lifetime, which is the basis for most of the guidelines in the GDWQ. Typically, the GDWQ assume the consumption of 2 litres of drinking-water per day by an average 60-kg adult for a lifetime (70 years), 1 litre per day for a 10-kg child and 0.75 litre per day for a 5-kg bottle-fed infant.

Besides microbial organisms, a few inorganic chemical substances, such as nitrate and nitrite (which can enter the source water from agricultural activity, sewage inflow or sewage cross-contamination in plumbed systems) and copper (which may leach into drinking-water from copper piping), may also be of health concern due to subpopulations that may be at risk from excess short-term exposures. For instance, methaemoglobinaemia may be caused by the temporary exposure of infants to nitrate and nitrite, among other contributing factors; and gastric irritation may result from short-term exposure to copper (WHO, 2004).

Potentially significant cumulative effects of repeated short-term exposures to chemical hazards should not be overlooked, as they may lead to long-term consequences.

2.1.3.2. Water quantity

An insufficient or non-existent quantity of potable water under pressure on board the aircraft for drinking, culinary purposes and personal hygiene can have an impact on the health and welfare of not only the passengers but also the crew.

There may not be enough water for the safe use of lavatories, which may lead to malfunctioning of some types of toilets, unpleasant odours, contaminated surfaces and an inability to wash hands. It may also lead to an inability to prepare or serve food in a sanitary manner, thereby impacting on the provision of safe food to passengers.

Adequate water intake during flight is also important to maintain health and well-being, although there is no need to drink more than usual (WHO, 2008b). The humidity in aircraft cabins gradually decreases on long-distance, high-altitude flights, sometimes reaching below 10% (optimum comfort is at approximately 50% humidity). While this low relative humidity does not cause central dehydration (Stroud et al., 1992; WHO, 2008b), it can cause discomfort for passengers and crew. Dry, itchy or irritated eyes, dry or stuffy nose, dry throat and skin dryness are among the most common complaints of cabin crew (Lee et al., 2000). Regular water intake and use of a skin moisturizer will minimize these symptoms, but it is possible that some individuals may become intolerant of contact lenses and have to revert to spectacle use.

The amount of water required for hand washing and other sanitation needs should be adequately dealt with in typical passenger aircraft designs.

2.1.4. Bottled water and ice

Bottled water is considered as drinking-water by some regulatory agencies and as a food by others (WHO, 2004). For many airlines, bottled water is the primary or exclusive source of water used for direct consumption on board aircraft, with the exception of hot beverages. International bottled water quality specifications exist under the Codex Alimentarius Commission (FAO/WHO, 2001) and are derived from the GDWQ. Since it is commonly designated as a food product, bottled water will not be considered further in this chapter, and the reader is referred to chapter 4 on food.

For the purposes of this Guide, ice supplied to aircraft for both drinking and cooling has been classified as “food”. Guidance pertaining to ice used on aircraft is contained in chapter 4 on food. The GDWQ apply to both packaged water and ice intended for human consumption (WHO, 2004).

2.1.5. Uses of potable water on board aircraft

Potable water is used in a variety of ways on board commercial transport aircraft, including direct human consumption, food preparation and sanitation/hygiene activities. Potential uses include:

  • preparation of hot and cold beverages, such as coffee, tea and powdered beverages;
  • reconstitution of dehydrated foods, such as soups, noodles and infant formula;
  • direct ingestion from cold water taps and water fountains;
  • reconstitution and/or ingestion of medications;
  • brushing of teeth in lavatories;
  • hand washing in lavatories and galleys;
  • cleaning of utensils and work areas;
  • preparation of hot, moist towels for hand and face washing;
  • direct face washing in lavatories;
  • onboard showering facilities;
  • emergency medical use.

Although some of these uses do not necessitate consumption, they involve human contact and possibly incidental ingestion (e.g. tooth brushing).

2.1.6. International Health Regulations (2005)

Annex 1 B 1 (d) of the IHR (2005) requires every airport specifically designated by a State to have or develop within a limited period the capacity to provide safe potable water supplies for travellers using airport facilities.

In accordance with Article 24 (c) of the IHR (2005), all States are required to take all practicable measures to ensure that international conveyance operators keep their conveyances free of sources of contamination and infection, which should include drinking-water. However, it is the responsibility of each aircraft operator to ensure that no sources of infection and contamination are found on board, including in the water system. For this purpose, it is important that these standards are being upheld on the aircraft, in terms of both the quality of the water taken on board from the source of supply on the ground and maintenance of water quality on board.

For all States, their competent authorities are required to ensure, as far as practicable, that the facilities at international airports are in sanitary condition and kept free of sources of infection and contamination, as per Article 22 (b). This includes providing potable water from a uncontaminated source that should be approved by the competent authority.

2.1.7. Overview of water safety plans

Water safety plans (WSPs) are the most effective management approach for consistently ensuring the safety of a drinking-water supply. A potable water source at the airport is not a guarantee of safe water on board the aircraft, as the water may be contaminated during transfer to or storage or distribution in the aircraft. A WSP covering water management within airports from receipt of the water through to its transfer to the aircraft, complemented by measures (e.g. safe materials and good practices in design, construction, operation and maintenance of aircraft water systems) to ensure that water quality is maintained on the aircraft, provides a framework for water safety in aviation. A general overview of WSPs follows; their specific application to the safety of drinking-water on board aircraft will be described in section 2.2.

A WSP has three key components, which are guided by health-based targets and overseen through drinking-water supply chain surveillance. They are:

  1. system assessment, which includes
    • description of the water supply system in order to determine whether the drinking-water supply chain (up to the point of consumption) as a whole can deliver water of a quality that meets health-based targets;
    • identification of hazards and evaluation of risks;
    • determination of control measures, reassessment and prioritization of risks;
    • development, implementation and maintenance of an improvement plan;
  2. operational monitoring, which includes identification of control measures that will control hazards and risks and verification (to determine whether the system meets health-based targets);
  3. management and communication, including preparation of management procedures and developing supporting programmes to manage people and processes (including upgrade and improvement).

The various steps involved in designing and implementing a WSP are illustrated in Figure 2.2.

Figure 2.2. Application of water safety plans.

Figure 2.2

Application of water safety plans.

For more information on general principles of WSPs, see section 6.7.1 of the GDWQ (WHO, 2004) and the Water safety plan manual (WHO, 2009).

2.1.8. Applicability of the GDWQ to the Guide to Hygiene and Sanitation in Aviation

The GDWQ describe reasonable minimum requirements for safe practices to protect the health of consumers and derive numerical guideline values for constituents of water or indicators of water quality. Neither the minimum requirements for safe practices nor the numerical guideline values are mandatory limits, but rather health-based guidance to national authorities to establish their own enforceable standards, which may also consider other factors. In order to define such limits, it is necessary to consider the GDWQ in the context of local or national environmental, social, economic and cultural conditions.

Nevertheless, given the global nature of air travel and the need for aircraft to board water from areas with variable and possibly inadequate standards of general hygiene and sanitation, the GDWQ or national standards should be followed, whichever are more stringent. This approach will provide passengers and crew with consistent reliable protection from the potential risks posed by contaminated drinking-water.

2.2. Guidelines

This section provides user-targeted information and guidance, identifying responsibilities and providing examples of practices that can control risks. Six specific Guidelines (situations to aim for and maintain) are presented, each of which is accompanied by a set of Indicators (measures for whether the guidelines are met) and Guidance notes (advice on applying the guidelines and indicators in practice, highlighting the most important aspects that need to be considered when setting priorities for action).

The guiding principle for this section is ensuring that water is safe for intended use. Five of the guidelines that fall under this principle deal with water quality, and one deals with water quantity.

Guidelines 2.2–2.5 can all be considered components under the umbrella Guideline 2.1. However, their importance in ensuring safe water quality in aviation warrants that they have additional detailed elaboration.

2.2.1. Guideline 2.1: Water safety plans

Guideline 2.1—Water safety plans are in place for each component of the water supply chain.

Indicators for Guideline 2.1

  1. Design and implement a water safety plan for the airport water source.
  2. Design and implement a water safety plan for the airport.
  3. Design and implement a water safety plan for the transfer point.
  4. Design and implement a water safety plan for the aircraft.

Guidance notes for Guideline 2.1

A WSP is an effective means of achieving consistency in ensuring the safety of a drinking-water supply. The entity responsible for each component of the drinking-water supply chain (i.e. water source, airport, transfer point or aircraft) should also be responsible for the preparation and implementation of a WSP for that part of the process. General roles and responsibilities for each such component are as follows:

  • Source water supplier (public or private): Role is to provide to the airport a safe water supply of sufficient quantity and quality. Responsibilities are to monitor the water system by sampling water and providing sampling results to the airport competent authority on request, advising the airport authority of any adverse results and action to be taken, and advising the airport authority when the water supply has or may become contaminated and of action taken.
  • Airport authority: Role is to maintain the integrity of the water supplied and to provide safe water to the occupants, travellers, visitors, workers, water haulers and transfer points to the aircraft within the airport grounds. Responsibilities are to monitor the water system by sampling water and sharing sampling results with authorities and also stakeholders on request and to advise not only the water supplier but all concerned parties who use their water of any adverse results and corrective actions. In some circumstances, the airport may be both the source water supplier and provider of treated drinking-water.
  • Water haulers (transfer point): Role is to provide water to the aircraft. Responsibilities are to maintain a safe water supply from the transfer point to the aircraft, to maintain the equipment in good working order, to monitor the water system by sampling water and sharing sampling results with stakeholders on request and to report adverse results and action to be taken to the aircraft operator and airport authority.
  • Aircraft operator: Role is to provide a safe water supply to the passengers and crew for drinking, culinary purposes and personal hygiene. Responsibilities are to maintain their onboard water tank(s) clean and free of harmful microbial contamination, to monitor the water system by sampling water, to share sampling results with stakeholders, to report adverse results to the competent authority and take corrective actions, and, when and where required, to advise the crew and passengers of the adverse results.

The WSP for an airport source water supplier and drinking-water provider may be fairly detailed owing to the size and complexity of the facilities, whereas WSPs may be relatively basic for transfers and on board aircraft. The WSP should be reviewed and agreed upon with the authority responsible for protection of public health to ensure that it will deliver water of a quality consistent with the health-based targets.

WSP objectives are met through:

  • development of an understanding of the specific system and its capability to supply water that meets health-based targets;
  • identification of potential sources of contamination and how they can be controlled;
  • validation of control measures employed to control hazards (see Figure 2.3 for examples of hazards);
  • implementation of a system for monitoring the control measures within the water system;
  • timely corrective actions to ensure that safe water is consistently supplied;
  • verification of drinking-water quality to ensure that the WSP is being implemented correctly and is achieving the performance required to meet relevant national, regional and local water quality standards or objectives;
  • provision (to include development, assessment and overall management, as necessary) of appropriate training for all personnel involved in installing, maintaining, operating and monitoring all components of the water supply and delivery chain identified in the WSP.
Figure 2.3. Examples of hazards in the aircraft potable water supply and transfer chain.

Figure 2.3

Examples of hazards in the aircraft potable water supply and transfer chain.

For more information on general principles of WSPs, see section 6.7 of the GDWQ (WHO, 2004) and the Water safety plan manual (WHO, 2009).

1. Airport water source

Airports should be supplied with the safest water available from the water provider. The condition of the municipal supply source water provided to the airport should be known and controlled. Piped water supply delivered to airports should be obtained from well operated and maintained systems that conform to GDWQ or national standards monitored by competent authorities. If the water provided at the airport does not meet the GDWQ or national requirements, the airport will need to either utilize a higher-quality source or provide water treatment to meet those quality goals.

2. Airport

The airport authority has the responsibility to ensure the availability of a sufficient quantity of appropriate quality water. An airport may receive potable water from either a municipal/public or private supply, or the airport operator itself may be the water supplier responsible for producing the water that it uses. In the latter case, the airport would be almost identical to a public water supplier in its operations and responsibilities. The potable water is delivered to potable water cabinets, water trucks, carts, filling stations and airport buildings through the airport's distribution system. The delivery of the potable water to the aircraft is by designated filling hoses connected to the airport water system either directly or indirectly through water trucks and carts.

Improperly managed drinking-water can be an infectious disease transmission route at airports just as it is in municipal supplies. Most municipal waterborne outbreaks have involved ingestion of water contaminated with pathogens derived from human or animal excreta, which could be either from water that is supplied from the source or from contamination by cross-connection in the distribution system. The aircraft is a closed system, and post-loading contamination should not readily occur with a properly designed system. At an airport, the transfer procedure between the airport water system and the aircraft is another significant potential contamination opportunity.

Another possible cause of waterborne outbreaks is cross-contamination within the airport distribution system. Airports should ensure that water in the airport is potable through operational monitoring and should implement rigorous programmes to control cross-contamination during loading, distribution and treatment (e.g. having a cross-connection and backflow prevention programme).

Periodic self-audits or inspections should be carried out in addition to routine water quality measurements; these may differ in complexity from audits performed on the transfer point or aircraft. Corrective actions or procedures should be established and implemented should contamination be shown or if improper practices are suspected. Communication of this information to public health authorities and other affected individuals, such as persons served in the airport or those with responsibility over the water transfer points, is essential.

An example of a WSP for an airport can be found in Annex A.

3. Transfer point

The water transfer points between the airport source and the aircraft onboard storage and distribution system present significant opportunities for contamination. Common equipment used to transfer water includes (but is not limited to) piping, hoses, potable water cabinets, bowsers, tanks, filling stations, refillable urns and jugs, and hydrants (including taps/faucets). Equipment should be constructed of appropriate materials (e.g. corrosion-resistant materials) certified for this application, properly designed, operated, labelled and maintained, and used for no other purpose that might adversely affect the quality of the water. Assumptions and manufacturer specifications for each piece of equipment need to be validated to ensure that the equipment is effective.

Potable water should be obtained from those transfer points approved by the competent authority. The lines' capacity should be such as to maintain positive pressure at all times to reduce the risk of backflow. There should be no connections between the potable water system and other piping systems. Backflow of contaminated water into the potable water system needs to be prevented by proper installation of piping, backflow prevention devices and plumbing. Water for drinking and culinary use on aircraft should not be taken from water closets, washrooms or other places where danger of contamination exists or may develop.

Post-type or wall-type hydrants are preferred, but ground-level-type hydrants can be acceptable when necessary. Where hoses are used for loading potable water on aircraft, the hydrant outlet should have a type of coupling that will permit quick attachment and removal of the hose. For a hose permanently attached to the hydrant outlet, a threaded fitting will be acceptable. Outlets to all hydrants should terminate in a downward direction or gooseneck, except that ground-level-type hydrants may discharge horizontally. When the hydrant is of the ground-level type or is located in a pit, precautions should be taken in the construction of the transfer point to ensure that drainage from the hydrant area and from the hydrant box are adequate to prevent flooding. In new servicing areas, hydrants with weep holes are not recommended. Hoses should have smooth interior surfaces, be free of cracks, be checked on a regular basis and be sufficiently durable to withstand hard usage. The nozzle on the end of the hose should be constructed so as to permit a tight connection with the filling connection of the aircraft and should be of a different size from that of any waste connections on the aircraft. All hose connections should be of the quick-coupling type, unless the hose is permanently attached to a water cart or hydrant. Water hose nozzles and the hose ends should not touch the ground or any contaminating materials, such as pools of water on the ground. Hose guard systems are designed in many forms. Guards, discs, balls or other devices, which will protect the nozzle end of the hose from contamination, should be provided and properly maintained. Valves at the filling end of such a hose should not be located on the nozzle side of the disc or protective device. The hose should be stored well away from wastewater equipment and on special reels or in lockers or cabinets that are used for no other purpose. Nozzles, fittings and linkages should be covered so as to avoid contamination. The hose should be flushed thoroughly before being used and periodically sanitized, and it should be immediately sanitized after any observed contamination from ground operations. Transfer procedures should be developed to ensure that contact with the ground and other contaminated surfaces is avoided.

The tanks should be designed so that they can be disinfected and flushed and should be provided with a drain that permits complete drainage of the tank. They should be labelled “DRINKING WATER ONLY”. The inlet and outlet to the tank should terminate in a downward direction or gooseneck and should be provided with caps or closures with keeper chains for protection against contamination. The inlet and outlet should be equipped with couplings of a type that permits quick, easy attachment and removal of the hose. When hoses are transported on the water cart, storage facilities should be provided on the cart to protect the hoses from contamination.

Potable water provided in refillable urns or jugs for use at water transfer points between the airport source and the aircraft onboard storage and distribution system should meet relevant international standards. In such cases, the filling area should be dedicated for this purpose only and should be free of food manufacturing waste and by-products, general waste and cleaning agents and should be constructed and maintained in accordance with health regulations.

Appropriate personal hygiene for employees handling water at the transfer point cannot be overemphasized, and responsibilities for potable water transfer should be considered exclusive and separate from wastewater handling to avoid cross-contamination. Under no circumstances should employees be tasked simultaneously with both wastewater handling and potable water transfer. Other issues to consider include the development of transfer procedures to ensure that contact of hose nozzles with the ground and other contaminated surfaces is not permitted and procedures to ensure that water trucks and carts are not parked directly adjacent to sewage equipment.

The above lists of equipment and processes are by no means exhaustive. It is essential that, given the wide range of transfer equipment and processes, the WSP is informed by a fundamental understanding of the specific transfer processes obtained through hazard and risk analysis of each system and each type of aircraft and developing standard operating procedures when appropriate (e.g. when coupling/decoupling from transfer point and aircraft). Periodic self-audits or inspections should be carried out and can complement routine water quality measurements; these may differ in complexity from audits performed on the airport or aircraft. Corrective actions or procedures should be established and implemented if contamination is shown or improper practices are suspected. Communication of this information to public health authorities and other affected individuals, such as those with responsibility over the aircraft, is essential (USFDA, 1995).

An example of a WSP for a transfer point can be found in Annex B.

4. Aircraft

If WSPs at the airport and transfer points have been developed and implemented correctly, the water provided to the aircraft should be of acceptable quality. If the available water being provided to the aircraft does not meet the GDWQ or national requirements, then the aircraft operator must take measures to ensure that water on board is safe. These may include, for example, a decision not to board water at that location or to obtain water from an alternative source, such as a contract provider.

Aircraft water systems include the water service panel, the filler neck of the aircraft water storage tank and all water tanks, refillable containers/urns, piping, treatment equipment and plumbing fixtures within the aircraft that supply water for use by passengers or crew. In modern aircraft, water is generally stored in tanks. These should be constructed of welded stainless steel or reinforced fibreglass. They feed, either by pressure or by gravity, all aircraft water outlets (i.e. hand-washing basins, galley taps, drinking fountains and water heaters). Tanks should be designed to drain completely. If the aircraft has only one tank or if several tanks are located together, there should be a single fill/overflow point; if, on the other hand, the tanks are located in different parts of the aircraft, each should have its own fill point. In all cases, the fill points should be separated from the toilet servicing panels to avoid cross-contamination. Drinking-water access points should be sited outside lavatories. If appropriate, the water should be cooled by passing through automatic coolers. All components in the water system should be corrosion resistant and suitable for use with hyperchlorinated water. On some aircraft, carbon filters are used to neutralize the chlorine in the drinking-water at the tap for taste purposes. On occasion, these are incorrectly described as purifying filters. If they are not serviced regularly, the cartridges may proliferate bacteria or even disintegrate. Also, once the chlorine content has been removed, the water has no protection against bacteria introduced downstream from the filter, and heterotrophic plate count (HPC) regrowth may also occur. Such filters should therefore be fitted at each water outlet. If desired, point-of-use treatment devices exist with the capability of removing, inactivating or killing microorganisms in drinking-water. Careful testing and selection are necessary to determine the appropriateness and performance characteristics of candidate devices. Point-of-use devices are intended not to replace disinfection of the bulk water, but to provide an extra safety measure, if it becomes necessary.

In some aircraft, potable water is stored in refillable urns or jugs or the aircraft tank supply is supplemented by an extra quantity in flasks. This practice is not recommended—particularly in the case of drinking-water—because of the great risk of contamination of flasks, since these are offloaded at all airports and may not always be properly disinfected before being refilled. However, in the case where refillable urns or jugs are used, suppliers of refillable urns or jugs installed as part of the aircraft onboard water storage and distribution system should meet appropriate international standards. Aircraft onboard water distribution systems incorporating refillable urns or jugs should be maintained using the original manufacturer's guidance or approved bottle change/cleaning procedures.

Manufacturer specifications and assumptions for proper use of each piece of equipment should be validated to ensure that the equipment is effective. Periodic self-audits or inspections should be carried out and can complement routine water quality measurements; these may differ in complexity from audits performed on the airport or transfer point. Corrective actions or procedures should be established and implemented if and when contamination is shown or improper practices are suspected. Communication of this information to public health authorities and other affected individuals, such as passengers and crew on board the aircraft, is essential (USFDA, 1995).

An example of a WSP for an aircraft can be found in Annex C.

2.2.2. Guideline 2.2: Drinking-water quality standards

Guideline 2.2—All water on board aircraft intended for human contact meets GDWQ or national standards, whichever are more stringent.

Indicators for Guideline 2.2

  1. E. coli or thermotolerant (faecal) coliforms are not detectable in any 100-ml sample.
  2. A disinfectant residual is detectable in water samples at the airport, at the transfer point and on the aircraft.
  3. All samples meet GDWQ or national standards for chemicals of acute significance or for chemicals with potentially significant cumulative effects from repeated short-term exposures.
  4. Temperature, pH, ionic composition and alkalinity are controlled within appropriate ranges for the particular water type to minimize corrosivity and potential leaching of metals, such as copper, lead and iron.
  5. Turbidity is monitored, and increases in turbidity are investigated to ensure that water has not been subjected to post-treatment contamination.
  6. No undesirable tastes, colours or odours are present in the drinking-water.
  7. All airport and aircraft hand-washing facilities supply potable, hot and cold running water or warm running water. Each drinking-water tap supplies running water at room temperature or colder. The temperature of the water is comfortable for its intended use, but not so scalding as to discourage use or inflict injury. Water pressure is sufficient for the intended purpose.

Guidance notes for Guideline 2.2

All of the water on the aircraft intended for drinking, food preparation or human contact should be potable and meet the GDWQ specifications or national standards, whichever are more stringent. Specific requirements applicable to water on aircraft are provided in Guideline 2.2. If the water provided at the airport, at the transfer point or on the aircraft does not meet the GDWQ or national requirements, the appropriate responsible entity must take measures to ensure that water on board will be safe. These may include, for example, providing water treatment, deciding not to board water at that location and/or obtaining water from an alternative source, such as a contract provider.

More detailed discussions can be found in the GDWQ (WHO, 2004).

1. E. coli or thermotolerant (faecal) coliforms

By far the greatest risks in drinking-water are associated with microbial contamination from human excreta sources. Escherichia coli or thermotolerant (faecal) coliforms are utilized as the indicators of potential contamination with pathogens associated with human excreta. Total coliforms are not necessarily indicators of faecal contamination, but may reflect lack of general cleanliness. Escherichia coli and thermotolerant (faecal) coliforms should be measured using generally accepted analytical techniques.

In some instances, local source water contamination may indicate the potential for presence of protozoan pathogens such as Cryptosporidium or viruses, whose presence may not be well indicated by E. coli or thermotolerant (faecal) coliforms and that require more stringent treatment. Based upon the findings of the WSP, additional controls and measurements may be necessary.

Heated water utilized for beverage and food preparation adds additional protection of pasteurization if the water is heated to sufficient temperatures for sufficient times. Some organisms, such as certain viruses, are more resistant and require more stringent conditions of time and temperature for inactivation, so water should be managed to ensure their absence.

2. Disinfectant residual

The presence of a measurable disinfectant residual in the water at the point of use provides valuable information that contributes to the assurance that the water is microbially safe for the intended use. First, it demonstrates that the water has been disinfected; then it indicates that some level of protection is being provided during transport and storage and that some control of bacterial growth is being provided. The most common disinfectant used is usually a form of chlorine; in that case, the residual could be free chlorine, hypochlorite or chloramine.

Chlorine disinfection of low-turbidity water with appropriate contact time and pH will control bacteria and viruses. However, some protozoa are resistant to chlorine disinfection, and their control requires other disinfectants or efficient filtration. If present, protozoa should be controlled by source water treatment (e.g. filtration or ultraviolet light for some organisms). The presence of the residual will be affected by the original dose, the disinfectant demand of the water, the type of disinfectant being utilized, the temperature, the time since application of the disinfectant and whether contamination has occurred since application of the disinfectant. A “free chlorine” residual is more biocidal than a “combined chlorine” residual, but combined chlorine will last longer and will suppress HPC regrowth. Disappearance of a free chlorine residual may also indicate post-treatment contamination. Other disinfectants, such as chlorine dioxide, are sometimes used; each has its strengths and weaknesses. Chlorine is a potent disinfectant, but its high chemical reactivity leads to a short life in the system. Chloramines are less potent disinfectants but are more stable in water for longer times. The disinfectant residual for chlorine should be no less than 0.2 mg/l and no more than 5 mg/l. As the concentration increases, the likelihood of taste detection increases.

3. Chemicals of acute significance

Because of the intermittent and short-term exposure to potential contaminants in drinking-water on board aircraft, the main concern, aside from microbial contamination, is associated with acutely toxic chemicals. A few inorganic chemical substances, such as nitrate and nitrite (which can enter the source water from agricultural activity, sewage inflow or sewage cross-contamination in plumbed systems) and copper (which may leach into drinking-water from copper piping) may be of health concern to certain subpopulations. For instance, methaemoglobinaemia may be caused by the temporary exposure of infants to nitrate and nitrite, among other contributing factors; and gastric irritation may result from short-term exposure to copper (see also No. 4 below). Potentially significant cumulative effects of repeated short-term exposures to chemical hazards (for frequent flyers or crew members, for example) should not be overlooked, as they may lead to long-term consequences. Water on board aircraft should meet the GDWQ or national standards, whichever are more stringent, for such chemicals.

4. Corrosion-related contaminants

Corrosion in plumbing systems is a function of the stability and aggressiveness of the water towards the surfaces and fixtures that the water will contact during transport and storage. Metals such as copper, lead and iron can be leached from some materials into the water and contribute adverse taste or, in some cases, health concerns. Excess copper or iron can cause metallic taste; copper can cause gastrointestinal upset; excess lead can cause cognitive deficits from long-term high-level exposure in young children. The GDWQ guideline value for copper is 2 mg/l; iron can be detectable by taste at about 0.3 mg/l and above; and the lead guideline is 0.01 mg/l. In lieu of or in addition to monitoring for metals, appropriate management could be achieved through a corrosion control programme. The materials used in the construction of all of the surfaces (hoses, couplings, pipes, tanks, fixtures, soldered joints) that the water may contact during production, transfer and storage should be approved for water contact by an appropriate authority (regulatory or independent third party) and meet appropriate standards. The water that is being provided should not be corrosive to those surfaces and fixtures. Factors such as temperature, pH, ionic composition and alkalinity need to be controlled within appropriate ranges for the particular water type (see WHO, 2004).

5. Turbidity

Turbidity (cloudiness) is caused by light being diffused by particulate matter that may be present in the water. However, it may not be obvious just from visual observation. Turbidity present in groundwater is usually of no sanitary significance if it is caused by inorganic matter. It can also be caused by sloughing of biofilms. Excess turbidity in water from the treatment plant can be an indicator of insufficient water filtration or inadequate control of coagulant dosing and sedimentation, and it could indirectly indicate inadequate removal of filterable microorganisms. Disinfectants function more effectively in low-turbidity water because microorganisms are often aggregated on particles rather than freely suspended in the water. Turbidity may increase slightly during transit through pipes due to particle agitation. A turbidity increase in the aircraft water after transfer from the airport to the aircraft could indicate that foreign matter has entered the system during the transfer. The GDWQ do not set a health-related turbidity guideline but recommend 0.1 nephelometric turbidity unit (NTU) as a process performance parameter for effective disinfection (WHO, 2004). However, this value is for water leaving the treatment plant rather than for water in distribution.

6. Aesthetic parameters (odour/colour/taste)

Aesthetic parameters such as undesirable taste, colour or odour that appear after water treatment may be indicative of corrosion or cross-contamination, cross-connections, contamination by foreign substances during transfer to aircraft or inadequate plumbing conditions on board the aircraft. They signify the need to determine their cause and to take corrective actions so that the water on the aircraft is both potable and palatable.

7. Temperature

Cool water is generally more palatable than warm water, and temperature will impact on the acceptability of a number of other inorganic constituents that may affect taste. High water temperature enhances the growth of microorganisms and may increase taste, odour, colour and corrosion problems (WHO, 2004) (see also No. 4 above).

2.2.3. Guideline 2.3: Monitoring

Guideline 2.3—Critical water quality parameters are monitored.

Indicators for Guideline 2.3

  1. Monitoring at airport water taps is carried out at locations to ensure that persons served by the airport are provided safe water. Recommended parameters that should be monitored at the entrance to the transfer point are E. coli or thermotolerant (faecal) coliforms, disinfectant residual, chemicals of acute significance, corrosion-related contaminants, turbidity and aesthetic parameters.
  2. Monitoring at the transfer point takes place to ensure that water boarded on aircraft is safe. Recommended parameters that should be monitored at the transfer point to the aircraft (includes bowsers, trucks, carts, hoses, refillables) are E. coli or thermotolerant (faecal) coliforms, disinfectant residual and, if required, turbidity.
  3. Monitoring on aircraft is carried out at locations to ensure that persons on board the aircraft are provided safe water. It is recommended that E. coli or thermotolerant (faecal) coliforms be monitored at representative taps (e.g. galley, lavatory, drinking fountains). The monitoring should take place at each major servicing, in addition to regular E. coli spot checks while in service. Complaints about aesthetic parameters (odour/colour/taste) will trigger further investigations into the water quality and may indicate the need to monitor for turbidity. Additional parameters to be monitored include chemicals of acute significance and corrosion-related contaminants. Disinfectant residuals are also measured after the aircraft has been disinfected and flushed.
  4. All critical parameters are monitored at a sufficient frequency to ensure safe water.

Guidance notes for Guideline 2.3

In addition to the GDWQ or national standards applicable to a particular component of the water supply chain:

1. Monitoring at the airport

The piped water supply delivered to airports should be suitable for distribution and consumption without further treatment, except as necessary to maintain water quality in the distribution system (e.g. supplemental disinfection, addition of corrosion control chemicals). In the event of contamination of the water provided to the airport, the airport should complete corrective action and notify the party responsible for transfer of water to the aircraft as soon as possible so it can take mitigation measures or prevent the boarding of contaminated water on the aircraft. Documentation (recordkeeping) of monitoring should be kept for assurance and analysis in the event of an incident.

No E. coli or thermotolerant (faecal) coliforms should be detected in any 100-ml sample of the water. A positive test may be an indication of potential pathogenic (primarily bacterial) microorganisms associated with human excreta.

The presence of a measurable disinfectant residual contributes to assurance that the water is microbially safe for the intended use. The presence of the residual will be affected by the original dose, the disinfectant demand of the water, the type of disinfectant being utilized, the temperature, the time since application of the disinfectant and whether contamination has occurred since application of the disinfectant. Disappearance of a disinfectant residual may also indicate post-treatment contamination.

Provided that water entering the airport conforms to acceptable standards as described above, the principal concern for chemicals of acute significance would be nitrate/nitrite contamination at the airport from cross-connections with the liquid waste system and copper leaching.

Corrosion in plumbing systems is a function of the stability and aggressiveness of the water towards the surfaces and fixtures that the water will contact during transport and storage. Metals such as copper, lead and iron can be leached from some materials into the water and contribute adverse taste or, in some cases, health concerns.

Turbidity that increases in the airport could indicate that dirt has entered the system during the transfer.

Detection of aesthetic parameters (odour/colour/taste) may indicate cross-connections with the liquid waste system.

2. Monitoring at the transfer point

Potable water for aircraft, including bowsers, water trucks, water carts, filling stations and potable water cabinets, needs to be obtained only from those water sources and water supplies that provide potable water of a quality in line with the standards recommended in the GDWQ (WHO, 2004), especially in relation to microbial, chemical and physical requirements. In the event of contamination of water at the transfer point, the party responsible for transfer of water should notify the airline as soon as possible so it can take mitigation measures or prevent the boarding of contaminated water on the aircraft. Documentation (recordkeeping) of monitoring should be kept for assurance and analysis in the event of an incident.

No E. coli or thermotolerant (faecal) coliforms should be detected in any 100-ml sample of the water. A positive test may be an indication of potential pathogenic (primarily bacterial) microorganisms associated with human excreta.

The presence of a measurable disinfectant residual contributes to the microbial safety of water for the intended use. The presence of the residual will be affected by the original dose, the disinfectant demand of the water, the type of disinfectant being utilized, the temperature, the time since application of the disinfectant and whether subsequent contamination has occurred since application of the disinfectant. Disappearance of a disinfectant residual may also indicate post-treatment contamination.

Turbidity that increases in the aircraft water after transfer from the airport to the aircraft could indicate that dirt has entered the system during the transfer.

3. Monitoring on the aircraft

Potable water should be obtained from those transfer points approved by the competent authority. In the event of contamination of water on the aircraft, the airline should notify persons on board as soon as possible and take mitigation measures or arrange for an alternative water supply. Documentation (recordkeeping) of monitoring should be kept for assurance and analysis in the event of an incident.

No E. coli or thermotolerant (faecal) coliforms should be detected in any 100-ml sample of the water. A positive test may be an indication of potential pathogenic (primarily bacterial) microorganisms associated with human excreta.

Detection of aesthetic parameters (odour/colour/taste) may indicate cross-connections with the liquid waste system. On some aircraft, carbon filters are used to neutralize the chlorine in the drinking-water at the tap for taste purposes. On occasion, these are incorrectly described as purifying filters. If they are not serviced regularly, HPC growth will occur, and cartridges may disintegrate. Also, once the chlorine content has been removed, the water has no protection against bacteria introduced downstream from the filter. If used, such filters should therefore be fitted at each water outlet. Complaints about aesthetic parameters may indicate the need to monitor for turbidity or HPC and/or take corrective action. Turbidity that increases in the aircraft water after transfer from the airport to the aircraft could indicate that dirt has entered the system during the transfer.

The principal concern for acutely toxic chemicals in water on board the aircraft would be nitrate/nitrite contamination from cross-connections with the liquid waste system and copper leaching from the distribution system. Other metals, such as lead and iron, can also be leached from some materials into the water and contribute adverse taste or, in some cases, health concerns.

Disinfectant residual should also be measured after the aircraft has been disinfected and flushed as per the aircraft manufacturer's specifications with a test kit that is specific to the disinfectant and used as per the manufacturer's specifications. The disinfectant residual for chlorine (the most common disinfectant) should be no less than 0.2 mg/l and no more than 5 mg/l. Testing of the disinfectant residual should be done at the cold water faucet of galley(s), fountains and some lavatories and prior to the filters being reinserted, where applicable. Results should be recorded. Should the disinfectant residual be above 5 mg/l, the flushing process should be repeated and disinfectant residual remeasured and recorded. It should be noted that monitoring of water in lavatories may detect contamination from the surroundings rather than from the water per se.

4. Frequency of monitoring

Regular monitoring of each parameter is necessary to ensure that safe water quality is maintained, as each step in the water transfer chain provides an opportunity for contamination. Documentation (recordkeeping) of monitoring should be kept for assurance and analysis in the event of an incident.

In certain situations, the frequency of monitoring should be increased for a period necessary to determine appropriate corrective action and/or assurance that measured parameters have returned to safe levels. Examples of situations warranting increased monitoring are positive E. coli or thermotolerant (faecal) coliform results, excessively humid conditions, during or after natural disasters affecting source water quality and immediately after maintenance activities that have the potential to affect water quality.

Aesthetic parameters such as odour, colour or taste are typically “measured” through customer complaints, although the crew may also wish to do an independent periodic check. This is a subjective parameter, as individuals have different sensitivities.

Some countries may request additional monitoring for parameters over and above those suggested by the GDWQ within their jurisdiction for operational or regulatory reasons. Airports, water haulers and aircraft operators should verify with their local competent authority if additional monitoring is required and what parameters the competent authority within their jurisdiction is requesting. These should be included in the WSP.

2.2.4. Guideline 2.4: Corrective action

Guideline 2.4—Appropriate response is ensured when the water safety plan is not properly implemented or a public health risk is detected.

Indicators for Guideline 2.4

  1. Investigative action and response procedures are established and documented.
  2. Investigative action and response procedures are implemented in a timely manner.
  3. Follow-up is performed to ensure that corrective action was effective and water quality is no longer of concern.

Guidance notes for Guideline 2.4

1. Establishment and documentation of procedures

Investigative action and response could be as basic as reviewing records or could include more comprehensive corrective action. Corrective action should involve remedying any mechanical, operational or procedural defect in the water supply system that has led to guideline values being exceeded or when other improper practices are suspected. In the case of mechanical defects, remedies should include maintenance, upgrading or refurbishment of facilities. In the case of operational defects, actions should include changes to supplies and equipment. In the case of procedural defects, such as improper practices, standard operating procedures and training programmes should be evaluated and changed, and personnel should be retrained. Any such changes should be incorporated accordingly into the WSP.

When there is evidence of contamination, appropriate action should be taken immediately to eliminate the public health threat of such contamination. Appropriate action may include additional treatment or flushing and disinfection of transfer equipment or aircraft water tanks.

In addition, emergency/contingency actions may need to be taken, such as the provision of water from alternative sources. During periods when corrective action is being taken, increased monitoring may be advisable.

2. Implementation of procedures

Investigative action and response could be as basic as reviewing records or could include more comprehensive corrective action. Oversight should be provided to ensure that corrective actions are implemented in accordance with written procedures and quickly enough to minimize exposure of the travelling public, employees, visitors, etc. Such oversight could be performed by the responsible party for that segment of the supply chain or by an independent party, such as a regulatory authority.

3. Verification of procedures

Verification steps should be adequate to provide assurance that water quality has been restored to safe levels. At a minimum, monitoring as described in Guideline 2.3 should be performed.

2.2.5. Guideline 2.5: Water quantity

Guideline 2.5—Potable water is available in sufficient quantities, pressures and temperatures for all uses at the airport, at the water transfer points and on the aircraft.

Indicators for Guideline 2.5

  1. Potable water quantities at the airport are sufficient to ensure adequate pressure at all taps to minimize the potential for contamination.
  2. Potable water quantities at transfer points are sufficient to ensure adequate pressure to minimize the potential for contamination and to replenish water supplies on board aircraft.
  3. Potable water quantities on board aircraft are sufficient to meet foreseeable needs for consumption, cooking and cleaning (e.g. food preparation, sanitation and hygiene activities) and to achieve sufficient water pressure at each tap to minimize the potential for contamination.

Guidance notes for Guideline 2.5

The amount of water required for all purposes on board an aircraft should be adequately dealt with in typical passenger aircraft designs. Quantities of water at all points in the water supply and transfer chain also need to be sufficient to ensure adequate water pressure in order to minimize the potential for contamination.

1. Water quantity at the airport

To achieve minimum pressures, a variety of water pumps or air pressure is used, while pressure-reducing valves are used when the system pressure is too great for the application.

2. Water quantity at transfer points

To achieve minimum pressures, a variety of water pumps or air pressure is used, while pressure-reducing valves are used when the system pressure is too great for the application.

3. Water quantity on the aircraft

Water supplies on aircraft must be sufficient to operate sanitary systems on the aircraft (e.g. vacuum toilet bowl rinsing rings). Additionally, food service fixtures, coffee makers, drinking taps and hand-washing sinks in the lavatories must have sufficient supply under adequate pressure to operate as designed. Water supply tanks on aircraft must be correctly sized and pressurized for these systems to work and serve passengers and crew, and they must be filled with sufficient frequency that meets expected use.

Water at sufficient pressure is required to operate fixtures and equipment on the aircraft. Most fixtures are rated to operate at certain minimum/maximum pressures. To achieve minimum pressures, a variety of water pumps or air pressure is used, while pressure-reducing valves are used when the system pressure is too great for the application.

2.2.6. Guideline 2.6: Independent surveillance

Guideline 2.6—Independent surveillance of drinking-water safety is performed by a competent authority.

Indicators for Guideline 2.6

  1. Audit/inspection procedures are put in place by a competent authority.
  2. Documentation of a water safety plan and its implementation are reviewed, and feedback is provided.
  3. An independent competent authority responds following reports of incidents with the potential to adversely affect public health.

Guidance notes for Guideline 2.6

Aviation water quality surveillance is an ongoing investigative activity undertaken to identify and evaluate potential health risks associated with the use and consumption of potable water in airports and on board aircraft. Surveillance contributes to the protection of public health by promoting the improvement of the quality, quantity, accessibility and continuity of potable water supplies. This guideline addresses surveillance of these factors only and does not address surveillance relating to monitoring of or response to outbreaks or other disease events (i.e. public health surveillance).

The levels of surveillance of drinking-water quality differ widely, just as economic development and provision of community water supplies vary. Surveillance should be developed and expanded progressively, by adapting the level to the local situation and economic resources, with gradual implementation, consolidation and development of the programme to the level ultimately desired. When accepting a WSP, the competent authority in a given jurisdiction may take responsibility for surveillance of the programme, which may include performing random water sampling and the auditing of the WSP programme.

Although this guideline addresses surveillance by oversight authorities, many of the concepts discussed here could be employed by the water supplier to ensure that the WSP is being implemented effectively.

1. Establishment of procedures

In most cases, surveillance consists primarily of sanitary inspections based on the WSP of airports, transfer points or airlines. Sanitary inspection is a tool for determining the state of the water supply infrastructure and the identification of actual or potential faults and should be carried out on a regular basis.

A surveillance agent should have the authority to conduct independent inspections and verify the reliability of the supplier's information. This does not normally need to be as frequent as the continuous control performed by airports/airlines.

Surveillance should be accomplished by authorized and trained officers from public health authorities, or the services of qualified independent auditors and inspectors may be utilized.

Specifications for qualifications of the inspectors should be established, and inspectors should undergo adequate training, including periodic updates and recertification. Independent auditors and inspectors should meet the same requirements as those from the public health authorities.

Annex D provides an example of a format that can be used by on-site inspectors in evaluating the sanitation status of the airline service area or transfer point. It can be adapted to specific circumstances and situations that may exist in various countries and airports.

2. Review of documentation and plan implementation

WSPs should be provided by the airport authority, water haulers (transfer points) and airlines, and all documentation pertaining to the WSPs should be reviewed. The independent review of the WSPs should include a systematic approach, based upon the components of the WSPs, by external auditing of the documentation, implementation and monitoring of critical control points.

Some of the components of the independent review include inspection of employee personal hygiene through demonstration of employees following procedures, inspections and the recording of these inspections of equipment and environmental conditions to ensure that dedicated equipment is used and stored in sanitary conditions, and water sampling through on-site or laboratory tests. Periodic microbiological surveillance of the entire water supply system from the source to the aircraft's galley and lavatory taps or fountains should be a key priority because of the acute risk to health posed by pathogens in contaminated drinking-water. Verification of compliance with water standards should start at the source and extend throughout the water distribution system. Each water point source, transfer point/critical point in the distribution system and end-point should be monitored. If this is not possible, at a minimum end-points should be monitored, but it should be possible to trace back when an unsatisfactory result is found.

Inspection of procedures or control systems should be adequate to provide assurance that responsible parties in the water supply chain are able to implement timely corrective measures. Supporting programmes should be reviewed to ensure that management procedures and training are adequate to ensure a safe supply of water.

Risk communication procedures by and to the water supplier, airport authority, water haulers (transfer points), airlines and the public should also be reviewed. A notification system should be established that integrates all parties within the water supply and transfer chain.

3. Response to incidents

Response to incidents may include written reports from the responsible party or parties or independent inspectors or written or verbal reports from affected individuals or their representatives.

The competent authority should investigate reports of incidents by interviewing reporters, responsible parties and other affected individuals and independently verifying water quality and relevant process parameters (maintenance checklists, training records, etc.) through on-site inspections and other means.

The competent authority should coordinate with and advise the responsible parties on appropriate corrective actions (modifications to water safety, management, training and maintenance plans, notification of potentially affected individuals, etc.) and ensure that remedial action plans are effective and implemented and that completion is verified.

Copyright © World Health Organization 2009.

All rights reserved. Publications of the World Health Organization can be obtained from WHO Press, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland (tel.: +41 22 791 3264; fax: +41 22 791 4857; e-mail: tni.ohw@sredrokoob). Requests for permission to reproduce or translate WHO publications – whether for sale or for noncommercial distribution – should be addressed to WHO Press, at the above address (fax: +41 22 791 4806; e-mail: tni.ohw@snoissimrep).

Bookshelf ID: NBK310709

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