Legionella is an ubiquitous environmental bacteria found widely in nutrient rich, moist and stagnant environments such as rivers, streams, ponds and even soil.
However Legionella can also thrive in man-made water systems such as cooling systems, humidifiers, domestic hot and cold water systems and spa pools.
It can be found in most common public places such as leisure facilities, hospitals and offices so it is important for your facilities operators to ensure they are adequately managing the risk of Legionella growth.
The bacteria becomes harmful when it is transmitted via an aerosol and is inhaled through pathways such as showers and cooling systems. Once in your lungs, depending on the susceptible person it could lead to Legionnaires' Disease.
It is quite rare to contract it in your own home, but it does happen. Landlords have a duty to keep on top of legionella prevention and regular checks for the safety of their tenants.