Post pandemic water management – your Legionella risk

Business Insights

If you took the decision to restrict access to all or part of your property during the Coronavirus crisis – or to close it completely – you must manage your Legionella risk carefully before you reopen it for normal use. This also applies to specific areas within buildings. If, for example, it has become the new normal for your employees or visitors to attend work in person only on an occasional basis, while continuing to work largely from home, you must exercise care in areas that are not used, or are underused for long periods.

Keeping it legal – legionella control is vital

The return to work, and the use of infrequently used parts of your water systems, will still fall under the remit of the Health and Safety at Work Act, and you have a legal requirement to manage the Legionella risk. From a microbiological perspective, the period between filling an unused system and bringing it into normal use is potentially the most hazardous. However, special care should also be taken with underused washroom facilities. People are creatures of habit and will often use the same washbasin or toilet. This could result in an operational washroom only being partially used. Some toilets or washbasins may be used frequently, others not at all. The same may apply to staff kitchens and breakout areas. Care must be taken to ensure that water does not stay static for long periods in any of them.

As good as new

Before any water system that has had its usage restricted, or that has been drained down completely, is put back into use, the system should be recommissioned as though it were new. When recommissioning, you must protect the integrity of the system and its users against the risk of Legionella proliferation and exposure, and the possibility of contracting Legionnaires Disease.

Key requirements during recommissioning include:

  • A new risk assessment. A full survey of the system including pipework, cold water storage tanks and hot water storage vessels should be carried out to determine if any remedial work is required following the changes to normal use.

  • The cold-water system should be disinfected (either via the cold-water break and storage tanks or by mains injection) using stabilised silver hydrogen peroxide, which should then be flushed fully through the system. This method of chemical disinfection will break down potential biofilms, including Legionella, within the system.

  • Hot water systems should be disinfected by cold water down service or by thermal disinfection. Thermal disinfection is achievable by raising the temperature to 70°C+ and allowing to circulate within the distribution system for at least 1 hour.

  • Water treatment plant such as water softeners and dosing equipment should be serviced and salt/chemical stocks replenished.

  • The storage tanks, hot water vessels and sentinel outlets should be sampled for Legionella prior to the recommissioning of the system to ensure the above tasks have been sufficient to remove the harmful risk.

Ongoing risk management

You must remain vigilant in managing your legionella risk as an ongoing task. There can be no let up on compliance once the Coronavirus crisis has passed, as Legionnaires Disease it itself a potentially fatal illness and a major public health concern.

In some ways, the ongoing challenge is more difficult than before. New work patterns may mean that employees do not attend in person daily, or even weekly. Some facilities, depending on their function, may be used to full capacity most of the time, while others are used only occasionally. This could mean that you will require a new Legionella risk assessment, especially for those areas which now have a vastly different pattern of usage to before the pandemic. Some areas may require additional routine flushing post pandemic. You may need the help of a Legionella risk control expert to help you to assess the situation, revise your risk assessment and put new legionella control schedules in place.

If you are in any doubt as to whether you can assess your post-pandemic Legionella control needs and responsibilities effectively, please contact our experts for assistance. We are members of the Legionella Control Association (LCA), so with Swiftclean you are in safe hands.

Please call us on 0800 243 471 or email for a free quotation and further guidance.