Legionella Risk During Summer Heatwaves: Protecting Water Systems and Preventing Outbreaks

10th July 2018

The longest heatwave the UK has seen for 5 years is still in full swing.  Temperatures of over 28 degrees were recorded for 16 consecutive days this year, and it’s conditions such as these that present perfect Legionella breeding conditions.

Landlords and facilities managers responsible for running of large commercial and residential buildings should be extra vigilant during hot periods and the summer months in general to ensure water systems are properly maintained and protected against this deadly bacteria.

Is my water system at risk of Legionella growth?

Legionella bacteria will thrive in stagnant water kept at a constant, warm temperature – anything between 20°C to 45°C will provide optimum conditions for bacteria growth.

From HVAC systems and cooling towers to sanitation and general plumbing, any man-made system has the potential to harbor Legionella bacteria.  If these particles become airborne, they can spread Legionnaires’ disease, so any component which disperses water droplets into the air, such as shower heads or jacuzzi jets, will pose a particular risk.

Hotels, hospitals, residential homes and office blocks – all are at risk of an outbreak of Legionnaires’ disease; when outside temperatures are elevated this risk is increased.

How can I mitigate the risk of a Legionnaires’ Disease outbreak in the summer months?

If you are an employer or someone in control of a premises, including landlords and building and facilities managers, you must understand the health risks associated with legionella.

A Legionella Risk Assessment will help you comply with your legal obligations and enable you to put an appropriate monitoring, maintenance and cleaning programme into place, ensuring water systems are healthy and free from bacteria growth.

However, legionella risk assessment should not be something you do once and year and then forget about.  During hot weather, it may be necessary to revisit the paperwork and amend care procedures, taking seasonal conditions into account.

Summer Legionella control essentials:

  • Hot water should be stored at 60°C or higher (Legionella bacteria will not survive at this temperature) and distributed at 50°C or higher.
  • Cold water should be stored and distributed below 20°C.
  • Check cold water tank temperatures more regularly during the summer months; they could easily become raised during extended periods of hot weather.
  • Insulate pipes and storage tanks to regulate water temperature.
  • Ensure there is no stagnant water in the system – remove dead pipework, flush infrequently used outlets on a weekly basis and make sure shower heads and hoses are suitable clean.
  • A competent person should routinely check, inspect and clean the water system.

Guardian Water Treatment can help you comply with your legal obligations by undertaking Legionella Risk Assessments and implementing and managing a suitable Legionella prevention scheme.

For more information, visit our Legionella Control pages.