Legionnaires' Disease and other forms of legionellosis can be contracted by the inhalation of water molecules containing legionella bacteria. Legionnaires' Disease can be fatal !
A low concentration of Legionella bacteria enters your engineered water systems from the mains water supply. Where water systems are not properly maintained, the bacteria are able to multiply to unsafe levels.
It is therefore a legal requirement, under the Control of Substances Hazardous to Health Regulations 2002 (CoSHH), to carry out a Legionella Risk Assessment, so that the potential for someone to contract a legionellosis can be determined.
Having a risk assessment, implementing a control scheme and evidencing safe operating conditions are essential to maintaining a water system, such that the risk from legionella bacteria is adequately managed.