Time to tackle 'dead leg' plumbing

Published:  13 March, 2014

Mark Dowdeswell, applications manager and plumbing expert at Uponor, says the UK heating and plumbing industry needs to rethink its design and installation methods to minimise the risk of legionella.

It has long been understood that ‘dead legs’ in plumbing systems are a major cause of legionella outbreaks and need to be designed out of the system to eradicate the problem.

Dead legs are created in T-piece plumbing, where it is possible for water to stagnate and breed the legionella bacteria. Unfortunately, the industry remains largely unaware of the problem, the risks associated with it, and the alternative plumbing methods that can eliminate the threat.

Dead legs are often immune to flushing, as they can inhibit the exchange of water. Similarly, temperature control is no guarantee because the dead legs in a system allow water to cool to a temperature where the bacteria can begin to grow.

We have guidelines, but that is all they are – a guide and not a formal regulation. If we are truly serious about eliminating the dead leg problem, we need to look at alternative plumbing methods, such as loop and serial installation techniques, which are the methods used in Continental Europe to great effect.

Loop and serial installations are more hygienic than traditional T-piece systems because the risk of standing or stagnant water is significantly minimised. We need an industry-wide effort involving the CIPHE and manufacturers to get this message across and, if necessary, offer the training plumbers and installers need to eradicate this problem.