Legionella: The forgotten threat

Tahira Duah 2019

Tahira Duah
20th May 2020

With the global focus currently on COVID-19, it is not surprising that the underlying threat of Legionnaires’ disease may have been put into the background by some. But health and safety laws still apply, and duty-holders still must demonstrate a control of risk.

Due to the current state of ‘lockdown’, many buildings have been left completely vacant or with minimal occupancy levels. This makes managing water systems more important than ever. As most people are now working from home, the demand for water in many commercial buildings has been tremendously reduced. Lower turnover rates, increased risk of stagnation and increased water temperatures as pipes warm all contribute to creating the ideal environment in which Legionella bacteria can thrive.

Individuals can be exposed to the bacteria by inhaling droplets of infected water, potentially leading to the onset of Legionnaires’ disease. A form of pneumonia, symptoms include muscle pains, headaches, fever and chills.

“After surviving COVID-19, who wants to open a building and have another set of significant safety issues?” asked Molly Scanlon of the American Institute of Architects. And she’s right! Especially in a post-coronavirus world, where weakened immune systems are likely to become more of the norm.

So, what can be done to reduce this risk?

  • Review the Legionella risk assessment and written control scheme currently in place, bearing in mind changes in occupancy levels and operations.
  • Identify all low use outlets and flush them on at least a weekly basis. Record this task within the water management system.
  • Establish whether any occupants or visitors are high-risk individuals and put additional control measures in place for protection.
  • Maintain routine temperature testing of your water system and carry out microbiological testing as necessary.
  • Re-commission any stagnated water systems as new (making sure that a specialist water treatment company is consulted with first).

Buildings which comprise high-risk plant, such as cooling towers, must be dealt with even more carefully. Wet cooling plant can generate high levels of aerosols during operation and must be appropriately maintained (in line with ACoP L8 and HSG274 Part 1). In this time of uncertainty, it is of paramount importance that competent staff continue to carry out essential checks and routine sampling. Any plant which cannot be suitably managed should be shut down and de-commissioned until further notice.

Ultimately, management is key to keeping people safe!