Legionella growth need the 3 requirements (temperature, oxygen and food). But still there are places in the installation where legionella grow fast: Tanks, plastic pipework, spa’s / wellness, stagnant water, cooling towers and large/complicated drinking water installations. Legionella contamination can only occur by breathing in aerosols (shower, cooling towers or jacuzzi) or by choking water while drinking.
Legionella can be found in many different sources, but can only be of human danger with it gets into the lungs. There are two different ways to get water in your lungs, breathing in the water aerosols or by choking water.