MGN 397 (M+F)
This Part covers fresh water loading and supply arrangements, disinfection, storage, distribution systems and maintenance
The Merchant Shipping (Crew Accommodation) Regulations 1997 and the Merchant Shipping (Crew Accommodation) (Fishing Vessels) Regulations 1975 require the supply of drinking and fresh water to be such as to prevent any risk of contamination. In addition the 1997 Regulations require the supply of hot, fresh water and cold drinking water to any sink, wash hand basin or other washing facility in a galley.
Improperly managed water is an established infectious disease transmission route on ships. Outbreaks of illness have been associated with contaminated bunkered water, cross connections between potable and non-potable water, improper loading procedures, poor design and construction of potable water storage tanks and inadequate disinfection. Evidence from outbreaks indicates that sewage is one of the more common sources of the pathogens that cause waterborne disease outbreaks on ships.
The most effective means of ensuring the safety of the fresh water supply is through the use of a risk assessment and management approach that covers the whole process from loading to delivery at the tap and includes a planned maintenance system. All of the information gathered should be used to develop a Fresh Water Safety Plan (FWSP), particularly for ships with a complex system, which could be incorporated into the ship’s planned maintenance system. An FWSP should be based on the following format.
System assessment and hazard analysis (including an assessment of source water loaded on to the ship)
Management plan and control measures, (the selection and operation of appropriate treatment processes)
Monitoring and corrective action system in accordance with the Plan (the prevention of contamination/re-contamination during storage and distribution).
Control measures (treatments) will be influenced by the quality of the source water. In the event of the potable water becoming unfit for human consumption then the tank(s) and distribution system should be drained, super-chlorinated and flushed in accordance with section 7 (Maintenance of water systems) below.
In addition to the above the ship should consider requesting water samples from the supplier prior to bunkering.