Hotel Service Unit 14 Q2

Fresh water taken on from ashore may require some treatment onboard a vessel even though it might have already undergone treatment at the source. This is because:

• Potential Contamination during Transfer: The transfer process itself can introduce contaminants, such as bacteria, from hoses, pipes, or the surrounding environment.
• Stagnation in Tanks: Water stored in tanks for extended periods can become stagnant, promoting bacterial growth even if it was initially clean.   1. Neglecting cleanliness: The hidden dangers of an unmaintained cold water storage tank wet-services.com
• Varying Water Quality Standards: The quality of shore-based water may not always meet the standards required for drinking water on board a vessel, especially in certain regions.

Therefore, the following treatment is typically required for fresh water taken on from ashore:

1. Chlorination:

• Purpose: To disinfect the water and kill any harmful bacteria or other microorganisms that may have been introduced during transfer or storage.   1. Water Disinfection with Chlorine and Chloramine | Public Water Systems | Drinking Water | Healthy Water | CDC www.cdc.gov
• Process: Chlorine, usually in the form of sodium hypochlorite or calcium hypochlorite, is added to the water in a controlled dose.
• Monitoring: The chlorine residual (the amount of free chlorine remaining in the water after disinfection) is regularly monitored to ensure it’s within the safe and effective range (typically 0.2-0.5 ppm).

2. Filtration:

• Purpose: To remove any suspended solids, particulate matter, or other physical contaminants that may have entered the water during transfer or storage.
• Process: The water is passed through filters, which can vary in type and size depending on the level of filtration required. Common filters include sand filters, cartridge filters, and activated carbon filters.

3. Testing:

• Purpose: To verify the quality of the treated water and ensure it meets the required standards for drinking water onboard.
• Process: Water samples are taken and tested for various parameters, including:
  • Microbiological contamination (e.g., coliform bacteria)
  • pH level
  • Turbidity (cloudiness)
  • Chlorine residual
  • Other relevant parameters based on local regulations or specific concerns

Additional Treatment (if necessary):

• UV Disinfection: In some cases, UV disinfection may be used in addition to or as an alternative to chlorination for further microbial control.
• pH Adjustment: If the water’s pH is outside the acceptable range, it may be adjusted using chemicals like soda ash or sodium hydroxide.   1. Sodium hydroxide – Wikipedia en.wikipedia.org
• Other Treatments: Depending on the specific water quality issues, additional treatment steps like softening, deionization, or activated carbon filtration may be employed to remove specific contaminants or improve taste and odor.

Key Points:

• Shore Water Quality: The extent of treatment required depends on the initial quality of the shore water. If the source is known to be reliable and meets drinking water standards, minimal treatment may be sufficient.
• Regular Monitoring: Regular monitoring and testing of the treated water are essential to ensure its continued safety and potability throughout the voyage.
• Crew Training: Crew members should be trained on proper water handling and treatment procedures to maintain the quality of the freshwater supply onboard.

By implementing these treatment measures and maintaining vigilant monitoring, ship operators can ensure that fresh water taken on from ashore is safe and suitable for drinking and other domestic purposes, safeguarding the health and well-being of everyone on board.

Water used for domestic purposes, including drinking, cooking, cleaning, and personal hygiene, must meet specific quality standards to ensure it is safe and suitable for human consumption and use. These standards encompass various properties, each with its own significance and treatment methods to achieve compliance.

1. Microbiological Quality:

• The water must be free from harmful microorganisms, such as bacteria, viruses, and protozoa, that can cause waterborne diseases.
• This is typically achieved through disinfection processes like:
  • Chlorination: Adding chlorine or chlorine compounds to kill or inactivate microorganisms.   1. What is Chlorination? – Safe Drinking Water Foundation www.safewater.org
  • Ultraviolet (UV) Disinfection: Exposing the water to UV light to damage the DNA of microbes, rendering them unable to reproduce.   1. Lethal Effects of UV Radiation. – The Virtual Edge www.uwyo.edu
  • Ozonation: Injecting ozone gas into the water, which acts as a powerful oxidant to destroy microorganisms.   1. Drinking Water Disinfection | Ozonation | Ozone Water Treatment – Water Professionals www.waterprofessionals.com

2. Chemical Quality:

• The water should be free from harmful chemicals and contaminants, including heavy metals, pesticides, industrial pollutants, and excessive levels of minerals.
• Treatment methods depend on the specific contaminants present, but may include:
  • Filtration: Using various filters (e.g., sand filters, activated carbon filters) to remove suspended solids, organic matter, and certain chemicals.   1. Water Treatment | Public Water Systems | Drinking Water | Healthy Water – CDC www.cdc.gov
  • Reverse Osmosis (RO): A membrane filtration process that removes a wide range of dissolved salts, minerals, and other contaminants.   1. Reverse Osmosis and Removal of Minerals from Drinking Water | IWA Publishing www.iwapublishing.com
  • Ion Exchange: Exchanging specific ions (e.g., calcium and magnesium for hardness removal) using resin beads.   1. Drinking Water Treatment: Water Softening (Ion Exchange) – Nebraska Extension Publications extensionpublications.unl.edu
  • Distillation: Boiling water and condensing the steam to produce pure water, leaving behind contaminants.   1. Drinking Water Treatment: Distillation. – Nebraska Extension Publications extensionpubs.unl.edu

3. Physical Quality:

• The water should be clear, colorless, and free from unpleasant tastes or odors.
• Treatment methods may include:
  • Filtration: Removing suspended solids and turbidity to improve clarity.   1. Suspended Solids Treatment – Definition | AWC – American Water Chemicals www.membranechemicals.com
  • Activated Carbon Filtration: Adsorption of organic compounds that cause taste and odor problems.   1. Drinking Water Treatment: Activated Carbon Filtration extensionpublications.unl.edu
  • Aeration: Exposing the water to air to remove volatile organic compounds (VOCs) and improve taste.   1. How aeration improves water quality – agriculture.canada.ca agriculture.canada.ca

4. pH and Alkalinity:

• The pH of the water should be within the acceptable range (typically 6.5-8.5) to prevent corrosion of pipes and equipment and ensure palatability.   1. How Do I Prevent Corrosion In My Water Systems? – ChemREADY www.getchemready.com
• Alkalinity provides buffering capacity to resist changes in pH.   1. Alkalinity and Water | U.S. Geological Survey – USGS.gov www.usgs.gov
• Treatment may include:
  • pH Adjustment: Adding acid or alkali to adjust the pH to the desired level.   1. Water Treatment | Public Water Systems | Drinking Water | Healthy Water – CDC www.cdc.gov
  • Lime Softening: Adding lime (calcium hydroxide) to reduce hardness and increase alkalinity.   1. Lime softening – Wikipedia en.wikipedia.org

5. Mineral Content:

• While excessive minerals can cause hardness and scaling issues, some minerals are essential for human health.   1. Definitions of Health Terms: Minerals – MedlinePlus medlineplus.gov
• Treatment:
  • Remineralization: If the water is demineralized through processes like RO or distillation, essential minerals like calcium and magnesium can be added back using mineral dosing or calcite filters.

6. Temperature:

• Water for domestic use should be at a comfortable temperature, typically between 10-25°C (50-77°F).
• Treatment:
  • Heating or Cooling: Depending on the source water temperature and ambient conditions, the water may need to be heated or cooled to achieve a comfortable temperature.

By employing a combination of these treatment methods and adhering to relevant water quality standards, it’s possible to ensure that the water used for domestic purposes on board a vessel is safe, clean, and palatable, promoting the health and well-being of the crew and passengers.