The availability of drinking water is a constant issue in the work environment, especially seafaring where it is occasionally compromised therefore leading to negative results such as illness. However, sometimes the supply is not the issue and instead the issue is its maintenance and means of distribution across the ship or port ecosystem; presenting our topic here.
Firstly, fresh water generation systems are provided on all ships alongside adequate storage arrangements; addressing long voyages and port stays. Generation of drinking water during operation of the main engine is done through waste heat, gained by circulation of cooling water for diesel engines, is the most effective method according to marineinsight.com. (2014) The generation and storage of water, though more accessible and higher in quality in the modern day is still a variable to consider as its quality is still an issue alongside risk of contamination as well as the quality of routine maintenance; also including actions if the water is not clean.
Beginning the discussion of routine maintenance, sampling should always be considered at least once a year when a sample should be taken from the galley and analysed, compared in terms of physical and chemical characteristics to normal drinking water along with monitoring for development of micro-organisms such as E-coli. Bunkered drinking water should be analysed with special focus on micro-organism along with considering the coating (if any) of the tanks which can contaminate the water with organic micro-contaminants. It is also worth noting that contamination can occur DURING the periodic tests.
Assuming that all periodical tests were passed and the ship is now on voyage therefore proper procedure will be discussed now. Obviously, the cleanliness of storage tanks is an essential variable therefore their cleaning procedure should always involve bio-degradable chemicals used in the procedure in order to avoid leaving residue/potential contaminants. However, leading back to bacteria and other micro-organisms, an excessive aerobic colony of bacteria counting at 22 degrees Celsius will be due to water tanks not being drained and cleaned adequately, recent work on the system or contamination from surface water.
Considering water produced on-board, it is done with reverse osmosis or distillation of seawater where contaminants can enter through leaks and the aforementioned seawater. Micro-organisms can also enter through seawater; examples of which are algae and cynobacteria. This can be fixed by distillation seawater more than 20 nautical miles offshore unless there is a risk of estuarial pollution where more than 20 nautical miles may be required. When using reverse osmosis or if water is distilled at lower temperature less than 80 degrees C/176F there is no guarantee of absence of micro-organisms; warranting further treatment.
Finally, the further treatment of water also incorporates measures which incorporate certain mechanics for maximum efficiency; this ranges from UV light to chemical and filtration. Micro-organisms are addressed with UV light without leaving chemical residue (commonly chlorine and silver) however if water is cloudy the method does not work therefore essential that the UV unit has an integrated filter before water passes through the radiation itself. The chemical methods of disinfection include chlorine and silver whose concentration should be 0.1- 0.3 mg/l for chlorine. The chemical residues, also have a way of removal by means of charcoal filters and treatment with other chemicals. Charcoal filters removes solvents, including chemicals such as pesticides found in unknown bunkering locations.