Legionella Disinfection of Water Systems
In this article the water hygiene and legionella specialists at Water Treatment Services highlight the need for the periodic disinfection of engineered water systems to maintain control over legionella and other potentially dangerous waterborne bacteria.
The article considers the most common methods for water system disinfection used in the UK, and why and when it is required. It looks at what’s involved, who should carry out the disinfection procedure, and concludes with a brief review of what records should be retained as part of the process.
Why disinfect a water system?
Stored water in any workplace represents one of the biggest water safety risks for bacterial contamination. High levels of bacteria, including legionella in water can cause all manner of serious medical conditions, including the potentially fatal Legionnaires’ disease.
Regular monitoring of your water systems should give you advance warning of any issues associated with a contaminated supply and the dangers that this can cause. If the levels of contamination go beyond acceptable levels then the water system should be disinfected in full, and as soon as possible. Prompt action should help to reduce water safety risk to customers and staff being exposed to Legionella bacteria and potentially contracting Legionnaires’ disease, or other illnesses caused by waterborne bacteria.
Water system disinfection to control legionella
A water system clean means disinfecting the whole water system, rather than just treating an isolated storage tank or a specific run of pipe work. There are two key ways of completing the disinfection process:
How often is legionella disinfection required?
In the UK current guidance from the Health and Safety Executive doesn’t set out any specific rules for the frequency of legionella disinfections of water systems. However, many water treatment specialists recommend disinfections are performed at least twice a year as part of their regular legionella control and monitoring process. This is to ensure that the water is as safe as it can be. In some situations, however, a one-off system disinfection may be needed. Possible scenarios can include:
How disruptive is a legionella disinfection to a business?
Disinfecting a water system might cause some interruption to business operations, but the level of disruption will largely depend on the type of disinfection being carried out. Thermal disinfection is typically quick and simple, and usually only takes a matter of minutes; long enough to allow the very hot water generated to run through the pipes, outlets etc.
Chemical disinfection on the other hand can be a lot more disruptive to operations. This is because the water outlets cannot be used for at least an hour – possibly longer – while the chemicals are working to sterilise the water system and kill any bacteria it comes into contact with.
It therefore makes good business sense to try to time any chemical disinfections for times when the water system isn’t being used, such as before work starts in the morning, in the evenings, or at weekends. This will keep disruption business operations and productivity to a minimum.
Who can perform legionella disinfections of water systems?
Whoever is chosen to take responsibility for the water system disinfection process should have the knowledge and skills to do it correctly, and be properly trained for the task. This is the same requirement for any water treatment task.
Most businesses choose to appoint an external water treatment specialist such as Water Treatment Services, rather than managing the process in-house. Many businesses will also ask to see evidence of competence or training for individual contractors who are coming on site to undertake disinfection activities.
What records to keep once the water disinfection is complete
Always ensure that after the disinfection works have been completed, that you get all paperwork, certificates and test results proving it has been done, and done correctly. The certificate from the contractor should show the date on which the work was carried out, the type of disinfection method used, details of any biocides used and their concentration.
It’s important to remember that the Health and Safety Executive requires that all paperwork connected with operations to control the risks from Legionella bacteria in the workplace is carefully recorded, and available for future inspection if required.
Expert Water Treatment and Water Safety Solutions
Water Treatment Services provide a comprehensive range of water and wastewater treatment, water quality analysis, consultancy, and water engineering solutions to support business owners and those responsible for the safe and efficient operation of water systems in the workplace.
Contact us today to learn how our water treatment specialists can help you manage your water systems, maintain regulatory compliance, and ensure safe, reliable performance.
With offices in London serving the South and South East England, Manchester (North West), Birmingham (Midlands), Bristol (South West England and Wales), Leeds (North and North East), and Glasgow (Scotland), supported by regional teams of highly trained technicians and engineers, we deliver specialist consultancy, water quality analysis, engineering support, and risk management solutions across the UK and internationally.
