Environmental consultants

Control of Legionella in Water Systems

Legionella is a genus of bacteria of the family legionellaceae. It currently consistes of at least 70 serogroups comprising over than 46 species. It has the ability to colonize water in distribution systems. It can cause disease in humans (e.g; Legionnaires disease or legionellosis) that is progressive and sometimes fatal(lifeless), or a midler form of pneumonic illness (Pontiac fever) that is self limited (i.e; heals on its own) with respiratory symptoms similar to influenza.

Legionella bacteria are common and can be found naturally in environmental water sources such as rivers, lakes and reservoirs, usually in low numbers. Legionella bacteria can survive under a wide variety of environmental conditions and have been found in water at temperatures between 6°C and 60°C. Water temperatures in the range 20°C to 45°C seem to favor their growth.

As Legionella bacteria are commonly encountered in environmental sources they may eventually colonize manufactured water systems and be found in cooling tower systems, hot and cold water systems and other plant which use or store water

This Guideline focuses on methods to control contamination and minimize the risk of legionellosis associated with building water systems. It provides advice and assistance to persons who design, install, own operate or maintain all building water systems.

It is consideredwith all water systems that can incorporate water in which legionella can grow and creates a water spray or aerosol such as cooling towers, evaporative condensors, hot and cold water systems, spas, fountains, waterfall systems, evaporative air coolers, misters, air washers and humidifiers