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Published on 03/05/2017

Potable water on ships: the top 5 most commonly asked questions

In the first instalment of our 2-part blog, we disclose the top 5 most frequently asked questions about potable water on ships, outlining the importance of properly managed water in storage and distribution systems and identify some of the serious issues that can result from contaminated potable water.

The implications of improper water management on ships can be incredibly serious. More than 50 incidents of Legionnaires disease, involving over 200 cases, have been associated with ships during the past three decades. In one incident alone, 50 seafarers became infected, resulting in one death. In addition, a high proportion of detected gastrointestinal disease outbreaks associated with ships have been linked to water consumed at sea, with contributing factors to the outbreaks including, inadequate disinfection of water and alarmingly, drinking water becoming contaminated by sewage.

If you’re no guru on this topic, don’t fear! We’re here to help you and your crew stay safe and get to grips with the ins and outs of potable water in the maritime industry. Let’s start with the basics: the top 5 questions and answers relating to potable water…

What does the term ‘potable water’ mean?

Potable water is water that is safe to drink, or use for food preparation without carrying the risk of health problems. Water that has not been adequately treated, cleaned or filtered may contain harmful bacteria and contaminants which may cause serious illness.

Why do you need to test potable water on vessels?

Access to fresh water is vital to ensure the health of those working at sea and a regular programme of potable water testing ensures that a ships ample supply of water for drinking, cooking and washing on board is safe to use.

How do ships obtain potable water?

Freshwater may be obtained from shore mains supply or water barge. Alternatively, the majority of ships employ an evaporator system that uses distillation, or a pressurised filtering system which uses reverse osmosis to convert seawater into potable water.

When the evaporator system is used, seawater is heated and turned to steam, before the fresh water condensate is collected. Alternatively, reverse osmosis forces seawater though progressively finer filtering to produce fresh water. Neither method is without drawbacks: both leave organic compounds such as benzene and trichloroethylene in the water which may be harmful to humans. The process therefore has to be managed carefully.

What are the implications of contaminated potable water on ships?

Improperly managed water in storage and distribution systems on ships can be an established route for infectious disease transmission. The importance of water was illustrated in the review of more than 100 outbreaks associated with ships undertaken by Rooney et al. (2004), in which one fifth were attributed to a waterborne route.

Furthermore, water may be a source of primary cases of a disease that might then be transmitted via other routes. Most waterborne outbreaks of disease on ships involve ingestion of water contaminated with pathogens derived from human, or other animal excreta. Illnesses due to toxic chemical poisoning of water have also occurred on ships.

Contaminated water may contain dangerous waterborne bacteria such as; Enterotoxigenic Escherichia coli, noroviruses, Salmonella spp, Shigella sp, Cryptosporidium sp, and Enterotoxigenic E. coli, which can affect humans when ingested as drinking water. Certain bacteria such as Legionella can even gain entry to the respiratory system from washing water suspended in the air, in the form of a fine mist created by a shower head.

How does potable water become unsafe?

Potable water may become unsafe for crew due to; contaminated bunkered water; cross connections between potable and non-potable water; improper water loading procedures; poor design and construction of potable water storage tanks, as well as inadequate disinfection.

So, you now know all about the dangers of contaminated water and the importance of properly managed water in storage in distribution systems on ships and that’s all for today! Don’t forget to tune in tomorrow for part 2 of our blog article where we outline all the relevant regulations relating to potable water on ships and tell you everything you need to know to ensure compliance.

If you have a burning question about potable water regulation compliance that won’t wait until tomorrow, then don’t delay! Contact us today for advice.