Practical Guide to Controlling Legionella in Water Systems

Practical Guide to Controlling Legionella in Water Systems

One could be forgiven for becoming overwhelmed at the number of tasks required to control the levels of Legionella bacteria in a water system. Typical systems that need to be managed include simple hot and cold water systems, cooling towers, spa pools, complex industrial process… the list goes on. However, there are some essential steps that should make it easier to ensure you cover all the salient points when assessing and controlling legionella risks in your own water systems.

Avoid the temperature “danger zone” for legionella reproduction

It is important to remember that Legionella bacteria will become dormant if the water temperature drops below 20 degrees Celsius and will start to die off if it goes above 50 degrees Celsius. Making sure water supplies do not sit within this thermal danger zone is of paramount importance yet should be easy to manage with a methodical approach to what is often called “thermal disinfection”. Ensuring your cold water remains cold, all water heaters (boilers, point of use heaters etc.) are set to heat your hot water to the correct temperatures, and flow and return temperatures are sufficient is important.

Keep your hot water HOT, and your cold water COLD

Avoid stagnant water

Stagnant water is far more likely to encourage the growth of Legionella bacteria (and other bacteria) when compared to moving water. There is a greater risk of bacterial growth within a rarely-used shower, for example, than there is within one that is used daily.

Keep your water MOVING

Avoid dead legs, rarely used taps or showers, and pipework that is no longer required

Infrequently used outlets, incorrectly sized water tanks, dead-legs and dead-ends are also areas of risk to watch out for.

If a water system is changed from its original use, there may also be changes to the pipework. Abandoned pipework or any similar scenario can easily raise the risk of legionella multiplying in that area. Such examples should be avoided wherever possible.

Avoid little used outlets and hide-outs

Take water samples and test them in accordance with your water safety legionella risk assessment

The frequency of such legionella testing will depend on the nature of the water system, whether it is deemed to be high risk, if it is suspected to be out of control, and where it is located. Open water systems, including cooling towers, pose a greater risk, as do those used by vulnerable people, either because of age or health. Water samples should be taken and tested in a UKAS accredited lab for accurate results. Details of all testing should be recorded and these records kept in a safe place for future reference.

Ensure a responsible person is appointed and they are competent to perform the duties required of them

The statutory duty holder must appoint someone to manage the risks from legionella in their workplace. This person is usually called the responsible person. They should put in place appropriate precautions to control the risks from legionella, starting with a legionella risk assessment. That person should be competent to perform their duties. They should have the experience, authority and knowledge to do their job – this may involve additional legionella training.

The legionella RESPONSIBLE PERSON must be competent to do their job

Essential reading if you’re tasked with controlling legionella in water systems

These points cover the essential areas you will need to consider if you are responsible for keeping water systems under control and so prevent the build-up of dangerous levels of Legionella bacteria. Much of it is common sense, including the need for regular checks and testing to ensure any rise in the levels of bacteria is spotted and remedied as quickly as possible.

In the UK the Health & Safety Executive offer a range of documents that are essential reading if you are involved in the control of legionella in water systems. These include their Approved Code of Practice ACOPL L8 and guidance HSG274 which covers hot and cold water systems, cooling systems and other risk systems.

International legionella and water safety specialists

Our teams of water safety specialists support those responsible for the control of waterborne pathogens including Legionella bacteria in the workplace, helping them to protect their people and meet their health and safety obligations in this specialist area. We deliver professional water safety legionella risk assessments, water testing, independent compliance auditing, City & Guilds training and other environmental risk management services that help keep staff and others safe.

If you have questions about any of the issues raised above or you would like to speak with one of our legionella specialists please call us today on 0330 223 36 87 or contact us here.