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Readers acting upon this article do so at their own risk and no responsibility is accepted by the author or publisher for any loss or damage incurred by following the article or failing to follow it.

If in doubt always consult a properly qualified tradesperson or other competent person.


'Legionella' (plural 'Legionellae') is the general name used for a type of bacteria found in water supplies.

When the bacteria are inhaled (e.g. in the mist from a shower head) they cause a severe illness similar to influenza.

The illness is frequently called "Legionnaires' Disease" after it killed 34 war veterans at a hotel gathering in the USA in 1976.

Legionnaires' Disease can be fatal in the elderly and those whose immune systems are compromised by other factors such as illness or medication.

Legionella bacteria are sensitive to temperature change but thrive in water stored in the range 20oC to 45oC.

Water temperatures below and above this range inhibit the growth of Legionellae.

Legionellae die quickly as the temperature of water increases beyond 50oC, with a temperature of 60oC or more being particularly effective at killing it.

However, water stored at a temperature between 20oC to 45oC provides an ideal breeding ground for Legionellae, particularly where the water remains undisturbed, such as in little-used pipes.

High risk areas for Legionella growth are water cooled air-conditioning systems, spas, low-use hot water pipes and shower heads, plus uninsulated cold water storage tanks and pipes during summer months.
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