Legionella - what is it?




What is Legionella?

Legionella is the bacterium that leads to Legionnaires disease. It is most commonly found in water and if not prevented, will begin to multiply in temperatures of 20-40°C with access to the right nutrients that they require. Legionella will lay dormant in water temperatures under 20°C and die in water temperatures above 60°C.


What is Legionnaires disease?

A type of pneumonia that is that is a potentially fatal disease, Legionnaires disease can be picked up by the inhaling of water droplets that are air born and contain Legionella bacteria. Legionella is formed in the water droplets by the condition's and temperatures of various different water systems. These water systems can range from anything such as hydrotherapy baths, whirlpools, and atomizers among other types. Theoretically anyone can contract Legionnaires disease, however, statistically those most likely to contract the deadly disease are the following: smokers, alcoholics, elderly people, diabetes sufferers or those that suffer from some type of respiratory or kidney problem.


What are the steps required to prevent Legionella?

When managing the prevention of Legionella in water systems, one should look to first assess and examine all possible areas that could be vulnerable to the development of Legionella. A first step should be to ensure that a full risk assessment of all cold and hot water systems is carried out. Applying these measures to best control the risk.


How do we manage this?

Once you have carried out a full risk assessment of site, water temperature control is an extremely effective method for reducing the risk of Legionella. By ensuring that all water system temperatures stay within the parameters that the Legionella cannot live and grow in, this will massively impact the safety of water systems on your premises.


The HSE state that the following rules are to be followed, in terms of controlling temperature at your site

- Hot water is to be distributed at no lower than the temperature of 50°C (thermostatic mixer valves will need to be fitted closely to outlets, where there is a risk of scalding identified)

- Hot water storage cylinders (calorifiers) must store water at no less than 60°C

- Cold water is to be distributed no higher than 20°C


Who should be maintaining Legionella compliance?

In terms of maintenance, ideally a professional with relevant experience and of sufficient competence should be routinely checking inspecting, and seeing to it that the systems are clean, all in accordance with the risk assessment carried out previously.


What steps should be taken to remain Legionella compliant?

- Focus on using materials that reduce the growth of Legionella

- Ensure that pipe work is as reduced in length as possible, keeping water routes short and direct

- Pipework and tanks must be as insulated as possible

- Avoid any contamination at all costs, with the fitting of lids and insect screens


The identification of outlets that are both furthest away and closest to each tank and cylinder on site is vital, ensuring that these are checked at least on a monthly a basis. The temperature of hot water storage cylinders are also to be tested monthly. Cold water tank temperatures require testing less frequently, on a 6 monthly basis.


What other control methods can be implemented?

There are a few other control methods that can be introduced to ultimately stifle the growth of Legionella. Both copper and silver ionization as well as biocide treatment are good methods to implement. To ensure that these methods remain fully effective, there implementation will require assessment, alongside the overall water treatment programme. This means that the correct installation, repair and maintenance, as well as monitoring will be needed.


How to best avoid water stagnation?

Avoiding stagnation of waters is key, to battle against the stagnation of waters, there a few steps that must be taken:

- Frequently flushing out infrequently used outlets such as shower heads and tap heads weekly

- Cleaning and descaling all shower heads and hoses quarterly.

- All cold water storage tanks are to be cleaned periodically, with water being drained from hot water cylinders, looking out for any debris and / or any signs of corrosion in the process.


What further steps can be taken?

Regularly monitoring the water samples taken and analyzing them to ensure that the bacteria levels are where they should be, will hugely benefit the goal of remaining Legionella compliant. The frequency of checking water samples will be completely determined by the risk assessment done prior, with the level of risk influencing this.


If you have any requirement for Legionella Compliance please don't hesitate to get in touch with us - 01604 696113.

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