Drinking water is a vital resource, not just for sustaining life, but for maintaining health and well-being. On ships, the quality of drinking water is especially critical due to the closed environment and the risks of waterborne diseases. This article outlines the regulations, procedures, and best practices for ensuring that drinking water on board ships is safe, clean, and potable.
Drinking water is categorized as a foodstuff and is therefore subject to strict water quality regulations. These rules are put in place to ensure the water consumed is free from harmful contaminants, including germs and bacteria, which could lead to serious health issues. On ships, maintaining the quality of drinking water becomes even more challenging due to the limited and variable sources of water available at sea.
To prevent contamination, drinking water should be sourced from reputable, clean supplies. On board, water must be stored in tanks that are either cemented or lined with high-quality materials. Modern multi-component coatings are acceptable, provided they meet drinking water safety standards. For smaller vessels, plastic or stainless steel tanks may be used. However, the materials must be certified safe for storing potable water.
Water storage tanks on ships should be kept in pristine condition, with regular maintenance and cleaning. Any damage to these tanks or the associated plumbing should be repaired immediately. It is essential that the hoses used for taking on water are designated solely for this purpose and are kept separate from other hoses, such as fire hoses. Hoses must also be clearly labeled to prevent misuse, as fire hoses are not permitted for taking on drinking water.
The ship’s officers are responsible for maintaining the cleanliness and functionality of the drinking water tank, pipes, and taps. Regular inspections should be conducted to ensure that the system is free from contamination. In cases where the water is suspected to be contaminated, appropriate measures should be taken immediately to identify the problem and resolve it.
In most major ports, the water at the taps is considered safe for drinking. However, in less clean or polluted ports, it is recommended to obtain a certificate from the health authorities to verify the water’s quality before use. Additionally, when taking on water from water boats in foreign ports, the ship's master must ensure that the boat’s water source has been certified as safe by the relevant health authorities.
In cases where the water supply is suspected to be contaminated with bacteria, boiling is an effective method for disinfecting water. Boiling kills bacteria and viruses that may be present in the water. However, it’s important to note that boiling does not eliminate chemical contamination, so it should not be relied upon as a solution in all cases.
Additionally, while on-board filters may improve water quality, they should not be assumed to provide complete protection against harmful bacteria. Filters need regular maintenance and cleaning, and their use can sometimes create a false sense of security if not properly cared for.
The drinking water system (including pumps, tanks, and pipes) must be kept entirely separate from other water systems aboard the ship. Any connection between the drinking water supply and other systems, such as ballast or bilge water, can increase the risk of contamination. Regular inspections should ensure that no cross-connections exist, and all testing instruments used to monitor the water supply must be properly maintained and used exclusively for this purpose.
Many modern ships are equipped with desalination units that provide fresh drinking water by distilling seawater. Reverse Osmosis (R/O) systems are commonly used for this purpose and generally produce water that is bacteriologically pure. However, distilled water produced from seawater may have an insipid taste due to its low levels of oxygen, salts, and calcium.
Aerating the water or adding minerals, as per manufacturer guidelines, can help improve its taste. In cases where the long-term use of distilled water leads to skin dryness due to its reduced hardness, applying a greasing ointment may help to alleviate skin irritation caused by the water’s drying effects.
R/O units typically produce clean water, free of bacteria. However, when these systems are not maintained properly, they may become a source of contamination. Ensuring that the R/O system is regularly serviced and following the operating instructions for chlorination and maintenance is critical for preventing issues related to waterborne diseases.
It is also important to remember that cold temperatures, even those below freezing, do not eliminate germs. Ice used in food and drinks must be made from potable water, as using contaminated water can lead to health issues. Ships should use only drinking water for ice production, and the water should always be handled according to hygiene regulations.
On average, each person requires around 2 liters of drinking water per day. This amount increases in tropical climates, where up to 3 liters per person may be necessary due to higher temperatures and increased perspiration. Besides drinking water, ships also require a large quantity of water for washing and other purposes, typically around 8-10 liters per person per day.
Older ships often have separate systems for drinking water, sewage, and seawater. Clearly marked signs should be placed on taps that do not provide drinking water to prevent accidental consumption of non-potable water. Taps in the galley, where food is prepared, should always be connected to the drinking water supply to ensure that food is prepared with safe water.
Continuous chlorination is one of the most common methods used to disinfect drinking water on ships. The goal is to add a disinfecting agent in a concentration that is safe for human consumption and effective at eliminating harmful microorganisms. The recommended concentration of free chlorine in drinking water is between 0.1 mg/l and 0.3 mg/l, though it may be increased to 0.6 mg/l if there are concerns about microbiological contamination.
Chlorine can be inactivated by certain chemical compounds in the water, which is known as chlorine drain. Therefore, it is important to regularly measure the chlorine levels in the water and adjust the dosage as necessary to maintain the desired concentration.
High chlorination is a more intensive method of disinfection that temporarily exposes the entire drinking water system or parts of it to a concentrated chlorine solution. This process eliminates microbiological contamination and ensures that all components of the system, including pipes and tanks, are thoroughly disinfected.
Before performing high chlorination, the tanks and system parts should be cleaned mechanically to remove any physical debris or contaminants. After chlorination, the system must be thoroughly rinsed with clean water to remove any residual disinfectant before the water supply is restored.
To disinfect drinking water, a chlorine bleach solution or calcium hypochlorite is typically added to the tank. The solution should be allowed to remain in the system for at least 30 minutes before use. After this period, the chlorine concentration must be measured to ensure it is within the recommended levels. Any readings under 0.1 mg/l require an additional dose of chlorine.
The process of disinfecting the drinking water system includes cleaning the tanks and pipes, followed by the application of a chlorine solution to ensure the system is free of harmful microorganisms. The system should then be flushed with fresh water before it is refilled with potable water.
Maintaining the quality of drinking water on board ships is essential for the health and safety of the crew. By following strict water quality regulations, ensuring proper storage and handling, and implementing effective disinfection methods, ship operators can minimize the risk of waterborne diseases and provide safe drinking water for everyone on board. Regular maintenance and vigilance are crucial to keeping the water supply clean and ensuring that the crew remains healthy during their time at sea.
By adhering to these best practices, ships can ensure the provision of potable water in a manner that meets the highest hygiene and safety standards, contributing to a healthier, more comfortable voyage for all.
