Water temperature plays an important role for bacteria growth in general and legionella growth specially. There is no need to make an argument whether the water temperature within the UAE or GCC area is high. So most of the cold water temperatures are between 25-45 ºC and supports an ideal water temperature situation for legionella to grow. Water temperatures above 60 ºC will start killing the legionella bacteria.


Temperature (ºC) Legionella growth

(+ growth and – die down)

<20 0
20-25 +
25-40 +++
45-50 +
50-55 0


* No legionella growth above 50 ºC. Between 55 ºC and 70 ºC legionella die down. Depending on time and temperature height, legionella bacteria will be killed slowly or quickly.

Oxygen in the water

Of course bacteria need oxygen to grow. Oxygen dissolves naturally when water comes in contact with air. This happens during production and storage in tanks. So oxygen is available in water for the legionella bacteria to grow. Especially water tanks and fire hoses will increase the oxygen level in the water.

Food for legionella

Bacteria need food to grow. So legionella needs food as well. Biofilm in tanks and pipework is where the food can be found by the legionella. This is why biofilm is called the breading ground for legionella bacteria.