Drinking Water

Clean drinking water is essential for life on board a ship and it is important to keep an eye on its quality.

About drinking water

Drinking water is defined as: All water either in its original state or after treatment, intended for drinking, cooking, food preparation or other domestic purposes, regardless of its origin and whether it is supplied from a distribution network, from a tanker, or in bottles or containers.
Since this covers water for other domestic purposes, such as personal hygiene (tooth-brushing, showering, and rinsing fruit and vegetables), it means that if in doubt about water quality, buying bottled water is not an option.


Contamination of drinking water can have major cost implications, both financially and for the health of the crew. That is why it is important to prevent contamination.  
There should be a plan on board for ensuring you have clean drinking water for the crew.  This means:

  • How will you do a risk assessment of the complete drinking water supply system to identify risks, critical control points and assessment?  
  • How will you ensure you have constant operational monitoring?
  • What actions should you take if the water quality or water system is not in order?

Keep an eye out yourselves

Everyone on board should be alert to differences in the taste, smell or clarity of the water.  If so, the water should be checked in addition to your regular checks.  

Analysing drinking water

There are four criteria for when you should have your drinking water analysed.

  • Bunkering water when the water quality is known and good.
  • Bunkering water when the water quality is unknown.
  • Production of drinking water onboard. The method of production is irrelevant.
  • If maintenance or repairs have been done to the drinking water system.


Bunkering water of known quality and water produced on board should be analysed annually in contrast to analyses done every time you bunker water of unknown quality and after maintenance work on the system.  Both requirements apply if you produce and bunker water to the same tank(s).

Samples should be taken for analysis at an accredited laboratory. But if you have the right equipment and skills on board, you can do it yourselves. 

If the results of an analysis exceed the threshold values, it is important to react.  In the first instance, it would be a good idea for you to contact Seahealth for additional assistance before making a start on various actions.  If the threshold value for E-coli has been exceeded, we recommend immediately boiling water before use.  You should also obtain bottled water at the next port of call.

In the ”Drinking water - on board ships” guidance, you can see the checks you must do on the water and in Annex 1 of the guidance, you can see the various threshold values.



Senior Occupational Health Consultant

Anne L. Ries


+45 3311 1833

+45 2961 8860

I can help you with:

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