The emerging threat posed by rising temperatures in cold water systems – particularly in modern buildings – and looks at possible solutions.
We are facing a battle to keep temperatures in cold water systems low enough to stop dangerous bacteria such as legionella from growing and multiplying. The past decade has thankfully seen few outbreaks of Legionnaire’s disease, the potentially fatal form of bacterial pneumonia caused by the ingestion of legionella bacteria. This is largely because the hot water systems in the UK’s buildings – once a common breeding ground for legionella – are now able to consistently maintain high enough temperatures to kill off the bacteria. Legionella occurs naturally in water environments and flourishes under certain conditions. Temperature is the biggest factor in determining risk. Between 25-50°C is considered high risk, however, the bacteria can still multiply between 20-25°C. Anything below 20°C and the bacteria can survive but will not multiply, while any temperature above 60°C kills it. Keeping our hot water hot enough was historically the biggest issue when it came to combating legionella. Now, it is making sure our cold water stays cold that poses the real challenge.