It’s not often you associate a ‘dead leg’ with plumbing! A ‘dead leg’ in plumbing terms however is no laughing matter, and is regularly being attributed to the breeding ground for Legionella, the bacteria which causes Legionnaires’ disease. Stagnant water in the pipework which runs from a hot water cylinder to the hot taps (a dead leg) results in the growth of Legionella, which multiplies in water temperatures between 20-60°C, thus producing highly infected water. Legionnaires’ disease is then spread by people breathing in small droplets of contaminated water. It is not, however, contagious and cannot be spread directly from person to person.

Legionnaires’ disease is an alarming threat in the home, however the threat to large commercial buildings, such as hotels, hospitals, educational institutions and office blocks, is even greater. These  larger, more complex water supply systems are highly vulnerable to Legionella contamination and this was highlighted by an outbreak in a warehouse, where the disease was the cause of 19 illnesses and one fatality.

In 2010 in the UK, more than 350 legionella outbreaks were officially reported, with ten of these cases resulting in fatalities.

Here is an NHS guide for spotting the symptoms of Legionnaires Disease:

Symptoms can begin any time from two to 19 days after exposure to the initial infection, although most commonly six to seven days.

The initial phase lasts one to two days, in which you will experience flu-like symptoms, such as:

  • Mild headaches
  • Muscle pain

This is followed by more severe symptoms, including:

  • High temperature (fever), usually 38ºC (100.4ºF) or above
  • More severe muscle pain
  • Chills
  • Tiredness
  • Changes to your mental state, such as confusion

Once bacteria begins to infect your lungs, you may also experience symptoms such as:

  • A persistent cough, usually dry at first but as the infection develops you may start coughing up mucus or, rarely, blood
  • Shortness of breath
  • Chest pains

Some people with Legionnaires’ disease also have symptoms that affect the digestive system, including:

  • Feeling sick
  • Being sick
  • Diarrhoea
  • Loss of appetite

A course of antibiotics is the prescribed treatment, and although the majority of infected people will recover completely, some sufferers with pre-existing conditions will suffer long lasting effects.

The medical profession state that the two most important factors for preventing an outbreak of Legionnaires’ disease are:

  • Temperature – any water in the system should either be cooled to below 20ºC (68ºF) or heated to above 60ºC (140ºF).
  • Hygiene – the water should be kept free of any impurities and never allowed to stagnate.

Since the plumbing trade have determined the ‘dead leg’ part of a plumbing system to be a major factor in the spread of Legionnaires’ disease, they are calling for the UK to follow Europe’s lead and tackle the problem head on.

Heating and Plumbing Monthly magazine were hot on the subject –

Plumbing“The UK heating and plumbing industry needs to rethink its design and installation methods to minimise the risk to health.

T-piece plumbing creates ‘dead legs’ where it is possible for water to stagnate and breed the legionella bacteria. Unfortunately, the industry remains largely unaware of the ‘dead legs’ problem, the risks associated with it, and the alternative plumbing methods which 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.

‘Chartered Institute of Plumbing and Heating Engineers’ guidelines state that the length of any dead leg should be limited to six times the pipe’s diameter, more commonly known as the six diameter rule. We have guidelines, but that is all they are, a guide not a formal regulation. If we are truly serious about eliminating the ‘dead legs’ 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.”

If you are worried about any of the above and would like to review your pipework, give us a call, we are here to help.

[Images by Leon Brocard and xandert]