Legionella: understanding and managing water hygiene risk

Managing and monitoring a water system to inhibit Legionella is a legal requirement, with any water system susceptible to outbreaks. So what should you know about Legionella prevention and what actions do you need to take?

Legionnaires' disease, the common name for Legionellosis, is a potentially fatal disease. It is a serious form of pneumonia, an infection that causes inflammation of the small air sacs in the lungs (alveoli) and their associated tissues. The disease is caused by the bacteria Legionella. Although many bacteria are benign or even beneficial, some can cause diseases in humans plants and animals.

Legionella bacteria can be found in man-made water systems such as hot and cold water systems, cooling towers and spas as well as natural water sources such as lakes, reservoirs, rivers and streams.

Legionella bacteria thrive in the following conditions:

  • when water temperatures are between 20-45°C
  • where nutrients, such as rust, sludge, scale, sediment and algae are present
  • where water is stagnant in the water system (for example, if a shower or tap is not regularly used).

The name Legionnaires’ Disease comes from the outbreak where it was first identified – in 1976 at a convention of the American Legion in Philadelphia. 29 People, mostly men, died.

During 2019 there were hundreds of cases worldwide, including six cases in London in September and two deaths in the previous month of British holidaymakers returning from a stay in a hotel in Bulgaria.

Control of Legionella Regulations

Due to the seriousness of the disease and its preventability, governments across the globe have introduced legislation governing the management of water systems and Legionella control. In the UK it is the legal duty of anyone responsible for a water system to undertake a risk assessment and address any issues identified.

The following health and safety legislation applies:

The last document in that list has been developed to help business owners and landlords conform to the legislation and carry out its requirements. It is an Approved Code of Practice (ACoP) with the current edition being L8 (Fourth Edition) published in 2013. It is commonly referred to by the shortened acronym, ACOP L8 and is available to buy as a book or download as a PDF for free from the Health and Safety Executive website.

By their very nature, hospitals and healthcare facilities have more vulnerable members of the public either on-site or visiting – at-risk groups include: people suffering from chronic respiratory or kidney disease, people who suffer from diabetes, lung and heart disease, or anyone with an impaired immune system. For this reason, the regulations regarding control of Legionella are more stringent. There have been several cases where patients have died after contracting Legionnaires’ Disease whilst in care at a facility where management of the risk was lax.

For these reasons, the healthcare sector should follow the Department of Health’s guidance: “Safe water in healthcare premises (HTM 04-01)” on Legionella control.

These legal obligations cannot be avoided, but the tasks can be outsourced. This is actually the most common route as Legionella prevention risk assessments need to be undertaken by competent, fully-trained assessors – it’s unlikely the average building or facilities manager will have the time or budget to become qualified in this specialist area, where clear and professional compliance needs to be demonstrated.

Risk assessments and their outcomes

Any system that might pose a risk should be subjected to a risk assessment. According to HSG 274, critical systems to assess are evaporative cooling systems and hot and cold water systems, along with any other water system that might produce airborne water droplets.

The first area to look at is the system’s infrastructure, with an inspection of obsolete pipework (dead ends) or dead legs such as plumbing to unused or seldom-used taps where water could stagnate and lead to the growth of Legionella bacteria. Where these have been identified, action should be taken to flush or (ideally) remove these water traps.

Where pipework or equipment joins is another area of risk - natural rubber, hemp, linseed oil-based jointing compounds and fibre washers have all been identified as potential breeding grounds for bacteria. If any of these are present, they should be replaced with suitable alternatives.

Ethylene Propylene Diene Monomer (EPDM) rubber can support the growth of Legionella microorganisms, so any flexible hoses made from EPDM should be replaced with safer alternatives. In theory, hoses made of EPDM should never be used in healthcare environments, although they are often found elsewhere.

All elements of the system should be inspected for corrosion, scale, sediment and biofouling (the accumulation of microorganisms, plants, algae, or small animals on wetted surfaces that have a mechanical function, causing structural or other functional deficiencies). Assets to be inspected would typically include cold storage tanks, calorifiers (hot water heaters) and evaporative cooling systems. If signs of any of these four are found – all potential factors in Legionella risk – then remedial action should be taken including cleaning and disinfection.

Legionella control and prevention

The legislation dictates that whoever is carrying out the Legionella risk assessment should be a competent individual with a full understanding of the relevant Codes of Practice and as such, the assessment should not be assigned to an under-qualified individual. In practice, this means that risk assessments are carried out by an experienced water treatment provider to ensure full compliance with the relevant legislation and a safe water system.

As every water system is different, it’s important to find a provider who can tailor-make their services to fit your situation by offering a bespoke risk assessment and risk management solution to suit your specific business and its individual requirements.

Legionella prevention should be a key priority for anyone responsible for the water systems of any building or facility. Effective Legionella control that complies with the UK regulations can be achieved by working with an experienced and qualified risk assessor from a water treatment provider, giving you peace of mind and safeguarding your business, its people and its customers.

Legionella Risk Assessment

James Greenwood

James Greenwood

James Greenwood as been working in the Water Treatment and Water Hygiene Industry for over 20 years. He is currently the Sales and Marketing Director for WCS Group the largest water hygiene and treatment Company in the UK. James has been instrumental in bringing significant innovations to the UK market over the years always focusing on enhancing client’s compliance and delivering true return on investment projects offering monetary and environmental savings.

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