Managing Hospital Water Safety - Legionella and Pseudomonas

In this article the healthcare specialists at Water Treatment Services review the challenges faced by healthcare estates, infection control and facilities management teams in the delivery of safe water supplies to hospitals and other healthcare premises. The article focuses on the risks presented by a number of common waterborne pathogens including legionella and pseudomonas.

The article begins by reviewing the water safety risk assessment process, and the role of the hospitals Water Safety Group and its Water Safety Plan. It then goes on to look at common risk factors, methods of control and who may be more at risk from the effects of Legionnaires’ disease and pseudomonas infection. It concludes by highlighting the role of the Water Safety Group, and in particular the benefits to be gained from the appointment of an independent Authorising Engineer (Water).

The challenge of maintaining safe water supplies in hospitals

It’s obvious that some building water systems are going to be more complex than others. Hospital water systems are perhaps among the most complex of all. They tend to be large, extending across several buildings, and contain lots of water outlets such as taps, showers, hydrotherapy pools etc. Older hospitals may have numerous extensions and renovations through their history, each one changing or extending the original water system. Even in modern hospitals, the specific requirements and demands of its occupants and specialist areas should be considered if the water systems are to be kept safe for use.

Assessing the risks in hospital water systems

Maintaining safe water systems in a hospital, or other building for that matter, is all about identifying and then assessing those risks for the potential to cause harm to those people using the building. Once that initial stage is completed, those risks that are identified must be carefully reviewed, so that actions can be taken to mitigate them. In healthcare environments a Water Safety Group (WSG) should be in place to create a Water Safety Plan (WSP) for the hospital. This safety plan should incorporate the findings of the risk assessment and any recommendations made to ensure all risks are either removed or controlled as appropriate.

Legionella bacteria in hospitals?

Legionella is perhaps one of the most familiar of those problematic waterborne bacterium that may exist in manmade water systems. While we are currently aware of around 70 specific species, it is Legionella pneumophila that is behind most cases of Legionnaires’ disease, the serious pneumonia like condition affecting the lungs.

What are the required hot and cold water temperatures in hospitals?

It is possible to keep legionella bacteria at levels deemed to be safe if the proper control measures are taken to achieve this. For example, legionella bacteria become dormant if the water temperature goes below 20 degrees Celsius. They die if the water heats to over 60 degrees Celsius. The risk point for water temperatures occurs at between 20-45 degrees Celsius. Therefore, cold water should always be kept below the 20-degree limit, and typically, hot water should be 50 degrees or more depending on the environment. It’s important to remember that the requirement in healthcare environments is for hot water temperatures to be a minimum of 55 degrees.

What are the growth conditions for legionella?

The idea of these waters temperature controls is to make sure that conditions do not allow legionella to multiply and reach levels where they could easily grow and start to spread within the water system. They also require nutrients for this to happen. These nutrients may come from rust, debris and scale within the water pipes, sludge and similar materials, and biofilms. Biofilms are more likely to occur in water systems that are not regularly treated or where sections are left unused for periods of time.

Another risk factor occurs where aerosols are allowed to occur. An example of this would be a shower spray. Legionella bacteria needs to get into the lungs to cause infection, and mist or aerosols contaminated with legionella bacteria are the ideal way for this to happen.

Are some groups of people more at risk from Legionnaires’ disease?

Of course, healthcare settings such as hospitals present another unique factor that the Water Safety Group must consider when adopting their Water Safety Plan. Certain groups of people are at greater risk of developing Legionnaires’ disease when exposed to the bacteria. Furthermore, they are at greater risk of becoming more seriously ill.

Hot water in hospitals and other healthcare environments should be a minimum of 55^oC

For example, older people and those with respiratory diseases that already affect their health will not be as able to fend off infection by legionella bacteria. Anyone suffering from an impaired immune system will also be at greater risk. Other diseases and conditions affecting the kidneys or heart would also be at heightened risk of contracting Legionnaires’ disease. Such people will need to be considered when conducting a legionella or water safety risk assessment of the hospital premises.

It may be that certain areas of the hospital water system require additional steps to be taken to reduce the risk still further. Hence why it is important for experts who are experienced in specific healthcare settings to be part of the Water Safety Group. Those with general experience of the hospital and its inner workings would not necessarily have the knowledge someone in a renal unit could supply, for instance.

Is Pseudomonas a risk in hospital water systems?

Another significant risk comes from Pseudomonas aeruginosa. This bacterium has great potential to do harm, especially within hospitals, nursing homes, and among patients using devices such as ventilators and catheters. The World Health Organisation have classified it as a critical priority pathogen because of its multidrug resistance. It can cause severe and often fatal infections such as bloodstream infections and pneumonia. It also works differently to legionella bacteria, which must come from a water supply and become airborne in aerosols for people to breathe in.

In the case of P.aeruginosa, it can come from the water system, particularly from a contaminated outlet or nearby section of pipework. However, it can be transferred to surfaces or equipment and survive there for some time. Indeed, one study discovered that it could survive on a dry surface for as little as six hours or as long as 16 months, depending on the conditions. While legionella requires specific conditions in which to thrive, P.aeruginosa is a little more versatile in remaining alive beyond the water system.

Pseudomonas aeruginosa has the power to cause nasty infections, and as with legionella bacteria, it holds notable risks for those who are ill or have weakened immune systems. Again, all those who are likely to receive hospital treatment to begin with are those who may also be at greater risk of any bacteria within the water system.

The World Health Organisation have classified Pseudomonas as a critical priority pathogen because of its multidrug resistance.

While legionella can be treated by antibiotics if caught early enough, Pseudomonas aeruginosa has shown itself to be a tougher customer. It is resistant to many antibiotics, although there are currently still some that can be used to treat those with Pseudomonas infections.

Water Safety Group and the role of the Authorising Engineer (Water)

Legionella still tends to grab the headlines when we are talking about contaminated water systems. However, Pseudomonas aeruginosa and other bacterial pathogens can also cause serious problems if a hospital water system is not properly risk assessed, and relevant infection control measures are not used.

The challenge of maintaining good water hygiene is clear. The role of the Water Safety Group is clear too in this scenario. Choosing a range of knowledgeable people in a number of roles from around the hospital and beyond is the best way to be sure of including everyone who should be in the group.

One role that is essential to the effective operation of the group is that of the Authorising Engineer (Water). The AE (Water) as they are often called is typically an independent professional advisor to members of the Water Safety Group, providing expert advice and guidance on issues that affect water safety. Once this group is in place and operational it should help make it much easier to identify all the potential risks present for all types of waterborne bacteria.

In some cases, however, it can still be prudent to bring in experts in legionella and water safety risk management, risk assessment, testing and control. It is often easy to miss something even when experienced in how people use the water system in a hospital setting. External advice and support can prove invaluable in this instance, strengthening the approach to total water safety in a hospital – a setting with perhaps more risk factors than many others. Identifying and removing as many of those risks as possible is hugely important to the ongoing safety of the water systems, and the people who use them.

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