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Recommendations for Recommissioning

Posted by Chloe on May 4, 2020 2:34:41 PM


As nations prepare their exit strategies for COVID-19, many commercial facilities that have been temporarily closed are making preparations to re-open. In some cases, where facilities have closed with little notice (perhaps overnight), water systems may not have been decommissioned with proper care.

For many businesses it may also be the case that control measures have not been maintained. Many water management professionals have been turned away from sites due to fear of spreading coronavirus. Thus, crucial maintenance such as weekly flushing may not have been carried out, potentially resulting in system stagnation, thermal gain and low disinfection residuals at outlets. These are all factors which contribute to the rapid growth of Legionella bacteria.

The potential risks for Legionnaires’ disease and other waterborne infections may well be overlooked when planning for a rapid increase in the number of patients during the COVID-19 pandemic but it really shouldn’t be, Legionnaires’ disease has similar symptoms to COVID-19 can be up to 10 times more fatal.

Studies looking at the rate of COVID-19 fatalities found that around half of all patients who died in China had suffered from a secondary infection. Further research by Chinese doctors, although in preprint and not yet peer-reviewed, found that 20% of COVID-19 sufferers were also infected with Legionnaires’ disease. This research suggests that COVID-19 put persons at an increased risk of developing other infections, such as Legionnaires’ disease, whilst in recovery and possibly for months following recovery. 

If buildings are not recommissioned with this in mind, we could face unprecedented, widespread Legionnaires’ disease risk when reopening the economy. The Legionella Control Association, a voluntary organisation based in the UK whose membership comprises providers of services and products concerned with the control of legionella bacteria in water systems, have stated that  

“The Health and Safety at Work Act still applies...Duty holders implicated in an outbreak of Legionnaires’ disease resulting from actions taken for COVID-19 precautions are not likely to have any exemption from prosecution” - Legionella Control Association.  

This means that business risks such as court action and fines could still be taken against negligent companies despite what is going on with COVID-19. 

To minimise the potentially devastating impacts on public health, and to reduce business risks such as fines, bad press and legal action, businesses should be proactive and careful when reopening their buildings and recommissioning their water systems. Here are some recommendations for recommissioning you should consider before reopening your facility.  


Recommendations from the Health and Safety Authority (IE)

The Health and Safety Authority, the Irish statutory body responsible for ensuring workers and those affected by work activity are protected from work related injury and ill-health, has published a pdf with the following advice. They maintain that water systems, if they have been controlled in accordance to Legionella control plans during COVID-19, can continue to be used and may not require further action.

However, water system which have been shut down or otherwise affected by the pandemic cannot go straight back into use without recommissioning. They recommend flushing, cleaning and disinfection, flushing of outlets and recommissioning by a competent person for wet cooling systems. They stress the importance of a risk assessment review and water testing as part of the recommissioning process.


Recommendations from the Legionella Control Association (UK)

The Legionella Control Association, a voluntary organisation whose membership comprises providers of services and products concerned with the control of legionella bacteria in water systems, are currently advising duty holders to draft up a recommissioning plan to ensure the safety of future water system users and state that is assistance from a competent person is needed, water management professionals should be consulted or contracted to help.

The LCA state that for smaller systems the minimum expectation is flushing with mains water. For larger or more complex systems flushing will need to be accompanied by cleaning and disinfection. They mention that all valves should be opened fully so that any matter within the pipes can exit.

Monitoring the level of disinfectant when cleaning and disinfecting is of great importance. The LCA state that a loss of 40% or more could suggest significant biofilm build up. They also mention that where buildings have been closed for extended periods, repeat disinfections may be required before the system is truly safe and that sampling is a useful tool for demonstrating the effectiveness of work carried out.

Cooling towers and evaporative cooling systems, considered to be some of the most high-risk systems for the dissemination of Legionella bacteria, should have start up and shut down procedures and these should be followed.


Recommendations from the European Society of Clinical Microbiology and Infectious Diseases Study Group for Infectious Diseases (EU)

The ESGLI also recommends system disinfection and flushing (all outlets should achieve 50 ppm free chlorine or equivalent for at least an hour at the outermost outlets). They say that systems should be flushed and refilled to “achieve maximum normal operating target levels of disinfection (equivalent to at least 0.2 ppm free chlorine)”, that the calorifier should be refilled and associated storage water should reach 60 °C before flushing through.

Temperature and disinfectant should be monitored for up to 48 hours and adjusted as needed. And as recommended by the LCA, Legionella samples should be taken from outlets to ensure that work has been effective and details of the work carried out and recorded for inspection.


It is important to remember that all water systems are different and may have specific requirements. Careful consideration from a competent person will be crucial for a safe and effective recommissioning process.

It is also valuable to note that demand for water management services such as Legionella testing and disinfection will grow significantly during the exit phase for COVID-19.

Supply chains may also be impacted. For example, there have been reports of a significant impact on availability of PPE/RPE, stocks of disinfectant and other consumables. Shortages of PPE/RPE has been reported globally and supplies of sodium hypochlorite for water system disinfection are likely to be in high demand when buildings reopen. 

Rapid on-site Legionella testing tools, like Hydrosense, can help speed up the recommission process for you and your clients and help mitigate risk under difficult circumstances. Not only does the simple test provide accurate results in only 25 minutes, significantly reducing the time required for individuals to be on-site, it can also be used in isolation by anyone, with the help of Hydrosense’s series of video instructions.

By providing accurate results for the most dangerous strain of Legionella bacteria, Legionella pnuemophila SG1, in only 25 minutes as opposed to 10-14 days like lab culture, Hydrosense can provide an ultra fast indication of the success of recommissioning, allowing businesses to get back to 'business as usual' quickly, and safely.

The LCA has released advise stating that you should make your clients aware of the potential for multiple outbreaks of Legionnaires’ disease following lockdown, as several rounds of cleaning and disinfection may be required. However, with Hydrosense the time taken to carry out multiple cleans can be reduced dramatically. 


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