The onboard water systems on ships are such a complex array of pipework and storage vessels they can become the ultimate breeding ground for potentially hazardous Legionella bacteria.

If people happen to come into contact with the bacteria present in the water supply, it can lead to serious illness and sometimes death.

In order to prevent this from happening, ship owners need to understand the causes of contamination and carefully monitor their potable water.

What are biofilms and where are they found?

We now understand that some Legionellosis outbreaks are linked to the existence of biofilms, so it’s critical to understand what a biofilm is, how to manage and control them, and ideally how to stop them from building up in the first instance.

By doing this, ship owners can take measures to reduce the likelihood of water system contamination. When it comes to contamination, prevention is always preferable to treatment!

A biofilm is formed when layers of microorganisms (typically bacteria) combine and stick to each other. Together they form a tough protective layer on a surface that encloses colonies of bacteria.

They can occur and bond to a range of man-made and naturally occurring surfaces, such as rocks and metalwork, with an obvious example onboard ships being the slimy layer that forms inside a drainage pipe.

In short, if there is a combination of moisture, surface and bacteria (this could be one species or several), biofilm can occur.

Can Biofilm help Legionella thrive?

The existence of biofilms in the ship’s pipework and water storage systems is an important factor for Legionella survival and growth.

The bacteria may be bonded to the inside of the water pipes, located on the surface of the water or in a typical drinking water outlet. Once established, it can be very challenging to eradicate these bacterial colonies completely, as the biofilm is a very robust, safe space for bacteria to thrive.

The biological process they go through enables microorganisms to tolerate difficult conditions like radical temperatures or a lack of nutrients. What’s more, they become much less responsive to biocide treatments, especially in areas of low water flow and where water can pool and stagnate.

Once Legionella bacteria have contaminated the system, they can expand rapidly if not dealt with, which could pose a serious health hazard on board.

What Causes Legionella to Grow? 

Your best line of defence as a shipowner is to understand how Legionella biofilms occur, and what you can do to reduce the problem and mitigate the risks.

There are several factors that are significant in the formation and control of biofilms in the ship’s water systems;

  • Temperature is a key factor for the establishment of a biofilm colony of Legionella pneumophila. Guidance shows that ensuring water is heated above 55 °C will reduce the amount of L. pneumophila in water systems.
  • The rate of water flow throughout the water system is critical to biofilm formation and colonization with L. pneumophila. Areas where water can stagnate are potentially virulent sites.
  • Organic debris and corrosion from aged or under-maintained systems can also pose a heightened risk by providing the right conditions for Legionella to take hold.
  • Evidence shows that Pseudomonas, another type of bacteria, is able to develop into a biofilm very quickly, due to its micro-porous and tacky properties. This makes it really easy for planktonic bacteria to manifest into a biofilm colony which can then expand. As it grows, this microbial material can break off and circumnavigate the water system, helping the bacteria to spread.

How Can You Prevent Biofilm from Forming in Your Water Supply?

With ships having such complex piping systems, it’s vital that provisions are in place to constantly check, identify and proactively prevent biofilm formation before it becomes a threat.

Water treatment experts recommend putting processes in place which cover the major risks and minimise the conditions where the bacteria will flourish if left unmonitored;

  • Maintain the correct water temperatures on board,
  • Ensure adequate and appropriate cleaning routines,
  • Allow a good flow of water to keep systems flushed out,
  • Preserve and use your ship’s equipment correctly to reduce debris etc making its way into the water systems.

Regularly following these recommendations will help prevent biofilm, organic material, and corrosion from polluting your water system, which would provide the perfect conditions and nutrients for Legionella.

Biofilm prevention is ultimately the most significant mechanism you can implement to stop the propagation of Legionella. Halting and controlling the growth of biofilms is key as they are so hard to eradicate from the complex water systems in ships. Left unchecked, prolific and uninhibited biofilms will hinder the water flow in pipework, resulting in areas of weakened flow and stagnation, with serious risk of Legionella growth.

Testing Your Water Systems for Legionella

To ensure your water system is free from harmful Legionella bacteria, it’s important that you not only follow the prevention process but also that you carry out regular checks on both water and biofilms.

The LegionellaMAX test kit is the most advanced, accurate and versatile testing technology for the rapid detection of Legionella bacteria, both in water samples and biofilms. The easy-to-use test needs no formal training, can be fully conducted on-site and delivers rapid results on within 35 minutes.

Knowing your water samples and biofilms are safe and Legionella-free within the hour is priceless. The last thing you want is a grounded ship while you tackle an outbreak.

For more information on the LegionellaMAX test kit, contact us and a member of our team will be happy to help.