Legionella bacteria thrive where water is warm and does not move. That makes two features of building pipework worth a closer look: dead legs and little-used outlets.
What is a dead leg?
A dead leg is a section of pipework that no longer serves an outlet, or serves one that is rarely used. Water inside it sits still, can warm up or cool unevenly and gives bacteria time to multiply. Dead legs are often left behind after refurbishments, when taps, sinks or equipment are removed but the pipe is not.
What is a little-used outlet?
This is any tap, shower or other outlet that is not used regularly: a spare bathroom, a staff shower, an old cleaner’s sink, a guest room outside peak season. Stagnant water builds up in the connecting pipework.
Why it matters
Legionella can grow in stagnant water within a building’s water system, and Legionnaires’ disease can follow if people breathe in contaminated spray or mist. A shower or tap that gets used only occasionally can release it in a fine spray.
What good management looks like
- Identify them. A legionella risk assessment includes a walk-through of the water system and flags these areas.
- Remove what you do not need. Where a dead leg serves no purpose, it can often be removed back to the main pipe.
- Flush what remains. Typically, little-used outlets are flushed regularly, often weekly, so water keeps moving. Flush hot and cold for a sensible time, keeping spray to a minimum.
- Record it. A logbook entry showing who flushed which outlet and when is exactly what your risk assessment will expect to see.
- Review after changes. Refurbishments, closures and new equipment should always prompt a fresh look.
Weekly flushing is common practice, not a legal rule, so your risk assessment should set the frequency that suits your building.
Your duties
Under the Safety, Health and Welfare at Work Act 2005, employers must identify and manage risks to the people who use their premises. The HPSC’s national guidelines on the control of legionellosis in Ireland give practical guidance on how to do that for water systems.
Let us take a look
A legionella risk assessment from Safer Solutions will map your water system and show you where problem areas lie, with clear, practical recommendations. Call 086 275 9728 or email info@safersolutions.ie to arrange yours.