WHAT IS LEGIONELLA?
(plural 'Legionellae') is the general name used for a type of bacteria found in water
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
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.