Legionella Control

A full copy of HSE’s Approved Code of Practice (ACOP) L8, the document detailing your legionella responsibilities, is available from the HSE. An electronic version of the document is available on the HSE website. It is vital that you always refer to ACoP L8, the HSE or a water treatment professional if in any doubt of the water treatment requirements or your legionella responsibilities on site.

Legionella is a bacteria that grows in the environment and engineered water systems. It was first identified following an outbreak at a Convention of the American Legion in Philadelphia in 1976. Legionnaires’ disease is usually contracted by inhaling the legionella bacteria in tiny aerosol droplets of water or the tiny specs of dust that remain once the water in an aerosol droplet has evaporated.

Legionnaires’ disease is a relatively rare form of pneumonia but is fatal in approximately 12% of the 300-350 cases reported in the UK every year since the start of the century. Certain groups of individuals are more susceptible to contracting Legionnaires’ disease, for example men and those over 45 years old, smokers, alcoholics, diabetics and those with cancer or chronic respiratory or kidney disease.

Legionella bacteria appear to grow best in water between 20°C – 45°C. For this reason it is important that systems which have the potential to grow legionella are closely monitored and treated. Unfortunately these systems are extremely common and present in most companies, including hotels and hospitals.

Two particular systems on a site pose a threat – cooling water systems and hot and cold systems.

Cooling Towers & Evaporative Condensers

Cooling towers and evaporative condensers pose a significant risk and, as a result, every company with a cooling tower or evaporative condenser must notify the local council so that they can be placed on a register. Cooling towers and evaporative condensers are high risk as they process water at a temperature within the 20°C – 45°C bracket and produce aerosols. Legionella outbreaks in the past have been traced back to cooling towers and evaporative condensers. The largest outbreak recorded in the UK is the Barrow-in-Furness outbreak. .

A legionella risk assessment must be carried out on cooling towers and evaporative condensers.

Cooling towers and evaporative condensers require servicing procedures such as routine analysis of the water quality; chemical level checking, internal inspection for signs of scale or corrosion, equipment checks, cleans and disinfections and descales where necessary.

It is also important that commissioning and re-commissioning of cooling towers and evaporative condensers is completed in line with a set programme and records are kept.

B & V Water Treatment has extensive experience in servicing and monitoring cooling towers and evaporative condensers from commission to operation. We can also advise on equipment or refurbishments.

Hot & Cold Domestic Water Systems

Hot and cold water systems must also be closely monitored and treated. Cold water tanks, hot water storage tanks, taps, showers and other hot or cold water outlets present a risk if not correctly maintained. For example, showers consistently run within the 20 – 45°C bracket; water stands in the pipework, the showerhead itself may stagnate and an aerosol is produced when in operation. This presents a legionella risk and if the shower is not used for a period of time they can pose a significant threat.

A legionella risk assessment must also be carried out on a hot and cold water system.

Hot and cold water systems require various servicing requirements such as; showerhead and hose descale and disinfection, sampling from showers, taps and other outlets, temperature monitoring of outlets, flushing of outlets that are infrequently used, cleans and disinfections of water tanks.

B & V Water Treatment have many years of experience in servicing and monitoring hot and cold water systems. We can also advise on equipment or refurbishments.

Temperature Monitoring

temperature monitoring

Temperature monitoring is an integral part of any water treatment regime on a hot and cold water system. Ensuring that temperatures within your system are outside the growth temperatures for legionella bacteria is a simple but extremely effective way to ensure that you minimise the risk of legionella within your system. Understanding how to monitor and maintain appropriate temperature ranges on your site is a key part of any legionella regime.

legionella samplingLegionella Sampling

It is recommended that regular samples are taken from hot and cold water systems and cooling water systems to monitor levels of microbiological organisms present within your system. This is to ensure that your system is free of any dangerous microbes and that your water treatment regime is working effectively. 


legionella A quick guide to legionella

First identified during an outbreak of the illness at a convention of the American Legion in Philadelphia in 1976, the illness is caused by a group of bacteria named Legionella pneumophilla. Since its discovery, legionella control has become an increasingly important aspect of water safety. There are now a number of codes of practice and legislation surrounding its effective management. To simplify this potentially complex issue we have put together a quick guide to legionella which will hopefully give a solid but quick over view of the topic.  

risk assessmentRisk assessments

Risk assessments need to be carried out on hot and cold and cooling water systems. A risk assessment looks in detail at the water system and identifies all of the potential legionella risks that are present within the system. . From the legionella risk assessment a water control regime can be developed to ensure that all the risks identified are managed as efficiently as possible in order to reduce the level of risk within the system.

Legionella control association logoLegionella control association

The Legionella Control Association (LCA)  was established 11 years ago and B & V Water Treatment have been members since its creation. Registration with the LCA ensures companies meet high standards of legionella control, with  membership requirements being improved annually. We believe that being a member of the LCA is a symbol of our commitment to providing the best possible service to our customers.


your responsibilitiesYour responsibilities

Your site has a legal requirement to control the risk from legionella. Legionella control is therefore a vital aspect of water treatment on site and it is imperative that the risk from this bacteria is assessed and managed effectively. To help give you a clearer understanding of exactly what you and your company’s responsibilities are when it comes to legionella control we have produced a guide to your responsibilities which you can view by clicking here.


For further information about the importance of legionella control and the solutions B & V Water Treatment can offer contact us today or download our legionella pack.


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