“Hidden threats in closed-loop water systems are increasing Legionella risk,” warns water safety expert
Hydrosense is urging building operators to rethink how closed-loop systems are designed and managed, warning that many common design and material choices unintentionally create ideal conditions for biofilm and Legionella growth.
Commonly found in building heating systems, air-conditioning and cooling systems, and some heat pumps, closed-loop water systems are often considered low risk for Legionella because they do not normally aerosolise water. However, in the face of rapidly rising Legionella counts in the UK, water safety expert Hydrosense has asserted that this assumption is misleading and that there are, in fact, a number of hidden threats in closed-loop systems that could increase the risk of Legionella.
Greg Rankin, CEO at Hydrosense, commented: “The reality is that modern closed-loop systems are designed to move heat efficiently, not to stop bacteria growing. Some common pipe materials such as PEX, PVC and EPDM can actually give bacteria an early foothold, while oversized pipes, dead legs and low-flow areas create warm, stagnant zones where bacteria like Legionella can thrive.”
In response, Hydrosense is calling for a greater focus on microbiological risk during design and commissioning, including minimising dead legs, avoiding oversized pipework, selecting low-leach materials, improving filtration, and ensuring robust flushing and monitoring regimes.
