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In August 2013, the Maritime Labour Convention (MLC) started to enforce their regulations (MLC 2006), Annex 2 of these regulations, relate specifically to freshwater loading and fresh water produced on board, supply, disinfection and storage arrangements, distribution systems and maintenance, aimed at maintaining high-quality drinking water onboard ships, to protect all on- board from waterborne health risks.
Yachts and marine vessels must provide an adequate supply of safe water for drinking, washing, preparing food, supplying recreational water such as pools and spas, fire control, dishwashers, laundry, air conditioning, boilers, deck washing, toilets and refrigeration.
Drinking water (potable water) consumed by crew, owners and guests must be provided under good hygienic conditions. It should be of an appropriate quantity and of a quality that it will not cause immediate or long-term harm to people drinking, washing or using it.
It must be free from any microorganisms, parasites, chemicals or other substances which, in the numbers or concentrations present, constitute a risk to human health.
Waterborne disease outbreaks may occur on Yachts and marine vessels due to failures in water safety systems.
Water is usually sourced from potable supplies on shore or generated at sea from sea water. Ensuring safe bunkering of water is essential to reducing potential risks for those on-board.
Yachts and marine vessels must ensure that bunkered water is of potable quality, as well as ensure that the actual process of bunkering, distribution and storage of water within the vessel is safe, that the equipment used prevents chemical or microbial contamination, in line with the WHO and International Water Association (IWA) guidance, the systems and controls for the provision of safe water on Yachts and marine vessels should be included within an overall Water Safety Plan (World Health Organization, 2008).
The most effective means of consistently ensuring the safety of a potable water supply is through the use of a comprehensive risk assessment and risk management approach.
This encompasses all steps mentioned above, in the water supply from bunkering and making water on board to showering, drinking and using the water. In these Guidelines, such approaches are termed water safety plans (WSPs). WSPs represent an evolution of the concept of sanitary surveys and vulnerability assessments that include and encompass the whole of the water making, bunkering and supply system and its operation. The WSP approach draws on many of the principles and concepts from other risk management approaches, in particular the multiple-barrier approach, hazard assessment and critical control points (as used in the food industry).
WSPs vary in complexity, as appropriate for the situation. In many cases, they will be quite simple, focusing on the key hazards identified for the specific potable water supply system. The wide range of examples of control measures given in the following text does not imply that all of these are appropriate in all cases.
The aim of the WSP is very simple, to ensure that the fresh water on board does not pose risks to health in either use or consumption, and is of sufficient quality to satisfy both those who use it and the requirements of the current rules, regulations and guidelines.
Benefits of a properly devised WSP include:
The WHO Guide to Ship Sanitation advises that there are 3 components to a WSP:
It should be noted that the description of the water supply system may include reference to areas outside the control of the vessel (e.g. the supply of water to the port).
However the system assessment will need to identify hazards involved in taking water from such sources, evaluate the risks and determine the control methods required.
Producing a WSP will, in most cases be a team approach. The following figure from the European Manual for Hygiene Standards and Communicable Diseases Surveillance on Passenger
Ships demonstrates the key stages of the process:
The first step in formulating a Fresh Water Safety Plan, is to assemble those who will be responsible for creating, monitoring and implementing the plan.
The persons responsible for conducting the risk assessment should have the knowledge:
The team leader/manager responsible for the WSP should:
The persons responsible for the every-day operation of the water systems should be able to:
Effective risk management requires the identification of potential hazards and hazardous events and an assessment of the level of risk presented by each. In this context:
System assessment is designed to determine whether the drinking-water supply chain (up to the point of consumption) including the sources of water, water bunkering and production, treatment, storage and distribution, can deliver water of a quality that meets identified requirements.
The assessment and evaluation of a drinking-water system are enhanced through an accurate system description, and should include a digital (where possible) plan of the vessels freshwater holding tanks and distribution systems (both hot and cold).
This should then be followed by a visual inspection to confirm any additional outlets or changes made since construction.
The system description should include all processes and components of the water systems from the source of water to the consumer.
The water processes and components that may result in direct human exposure (ingestion, contact, and inhalation) should be identified and described.
The data should then be compiled into a list to ascertain the exact number and nature of water outlets.
All connections to non-potable supplies such as black/ grey water treatment systems, air conditioning units etc. should also be noted.
Areas that should be taken into consideration as part of the assessment of the drinking- water system include all real or potential hazards and hazardous events associated with each step in the drinking-water system that could result in contamination or interruption of potable water on- board.
A structured approach is important to ensure that significant issues are not overlooked and that areas of greatest risk are identified.
The overall assessment of the drinking-water system should take into consideration any historical water quality data such as past analyses and system operational data, that may assist in understanding the drinking-water system performance both over time and for the future.
Special consideration should be given to the following
Possible hazardous events should include at a minimum:
2.4.1 Contaminated water
2.4.2 Contamination filling during bunkering, production and treatment
2.4.3 Contamination during storage
2.4.1 Contamination through the distribution system
Contamination of potable water or microorganism growth in the distribution system in particular due to:
Once potential hazards and their sources have been identified, the risk associated with each hazard or hazardous event should be compared so that priorities for risk management can be established and documented. Although there are numerous contaminants that can compromise drinking-water quality, not every hazard or hazardous event will require the same degree of attention.
The risk associated with each hazard or hazardous event may be described by identifying the likelihood of occurrence (e.g. certain, possible, rare) and evaluating the severity of consequences if the hazard occurred (e.g. insignificant, major, severe). The aim should be to distinguish between important and less important hazards or hazardous events. The approach used typically involves a semi-quantitative matrix.
Simple scoring matrices often apply technical information from guidelines, scientific literature and industry practice with well-informed knowledge and experience of a water treatment specialist.
Scoring is specific for each system within the vessel, as each system is unique.
By using risk ranking, control measures can be prioritized in relation to their significance. A variety of semi-quantitative and qualitative approaches to ranking risk can be applied. An example of a semi-quantitative approach is given in Table 1.
An example of descriptors that can be used to rate the likelihood of occurrence and severity of consequences is given in Table 2. A “cut-off” point must be determined, above which all risks will require immediate attention. There is little value in expending large amounts of effort to consider very low risks.
Item |
Rating |
Definition |
Likelihood Categories |
||
Almost Certain |
5 |
Once per day |
Likely |
4 |
Once per week |
Possible |
3 |
Once per month |
Unlikely |
2 |
Once per Year |
Rare |
1 |
Once every 5 years |
Severity Categories |
||
severe |
5 |
Possible health impact |
Major |
4 |
Regulatory impact |
Moderate |
3 |
Aesthetic impact |
Minor |
2 |
Compliance impact |
Insignificant |
1 |
No impact or not detectable |
Suitable control measures must be identified to ensure the prevention of potable water contamination incidents. All control measures for significant hazards or hazardous event must be assessed and recorded. The measures should be indicated on the flow diagram/table corresponding to the possible hazardous events.
Control measures include water treatment procedures, routine monitoring and inspections, maintenance, repair or replacement of equipment, cross connection control, labelling of pipes and hoses and training of the crew, temperature controls and flushing of infrequently used equipment.
Validation is an investigative activity to identify the effectiveness of control measures. It provides the evidence that elements of the WSP can effectively meet the water quality targets.
Potable water produced at sea using reverse osmosis plants are considered to be private water sources and should be controlled as such with appropriate monitoring and risk assessment.
Control measures must be monitored in order to spot any deviations from the operational limits. Operational monitoring should include measurement of selected water parameters, and the equipment and construction inspection procedures.
Operational monitoring must provide early warning of failure of the on-board sterilization system or any other operational limit violations to enable effective water system management. In most cases, operational monitoring involves basic weekly water quality tests (pH, sterilization residuals, mean distribution water temperature and TDS) and routine hygienic inspections.
An operational monitoring plan should be put in place and include the following basic elements:
Auditing the performance of control measures requires setting of operational limits for each one. An operational limit is a criterion which indicates whether the control measure is functioning as designed.
Operational limits might be either the upper limits or lower limits of the parameter values (such as pH, Sterilization residual, temperature, TDS) or visual factors.
Regular analysis is an important factor in the WSP, the more often it is performed, the higher the chance of finding any problems at an early stage and the higher the chances of fast, successful remedial action. Regular testing has been shown as a high value, preventative maintenance tool for any WSP, reducing costly down time, charter loss and ensuring the confidence and safety of the drinking water on-board.
Corrective actions are to be taken when the results of monitoring at a control point indicate a loss of control and may include repair or replacement of equipment, Hypo-chlorination, shock dosing with HydrasilAg+, flushing and dumping and then re-bunkering or reloading, etc.
Corrective actions should include the following steps:
The documents required include the following:
Supporting programs may include the following:
Regular audit of record keeping activities and other activities should take place at main control measures, including test results, data analysis.
Auditing includes;
a) checks of the records of the corrective actions taken in response to main non-conformances at the main control measures and
b) audit of practices to check that they are being used including taking corrective actions in case of non-conformance. Responsible person for regular audit is the team leader.
Periodic audit should be conducted:
Periodic audit should include the following, in addition to review of the WSP:
In order to provide a final assurance that the water supply system is operating safely, verification monitoring should be established. This includes:
This is an incomplete example of a WSP for illustration only.
World Health Organization. (2011). Guidelines for drinking-water quality. 4th edition. World Health Organization. (2009). Water safety plan manual (WSP manual)
Step-by-step risk management for drinking-water suppliers
EU SHIPSAN ACT / SHIPSAN TRAINET (2015). European Manual for Hygiene Standards and Communicable Disease Surveillance on Passenger Ships.
Manufacturer | Octo Marine |
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Compatible | Octo Marine |