This paper aims to provide a brief, non-technical overview of Legionella and Legionella related risk.
Given the right conditions all water systems are susceptible to colonisation and need to be managed, treated and measured to ensure safety.
HISTORY and BACKGROUND
Legionella are a group of naturally occurring water-borne, rod shaped bacteria that can cause Legionnaires disease, Pontiac Fever and Lochgoilhead fever.
Legionnaires’ disease first came to attention in 1976 when an outbreak of pneumonia affected 221 men attending an American Legion conference, thirty-four of those infected died. The bacterium, which was later found in the air-cooling system of the hotel, was called legionella pneumophila, and the disease was later called legionnaires’ disease.
Legionella bacteria can be found everywhere in natural water and ground water, but in very low concentrations. However, since the second half of the 20th century they have come into greater conflict with humans. This is due to the fact that we have developed technical water systems that provide ideal growth conditions for bacteria and have coupled these with human exposure routes.
Problems arise when
• The bacteria are able to colonise warm water systems and develop high concentrations,
• When they can infect people via inhaled water droplets,
• When the human body cannot (because of an immune weakness) fight the infection.
For building managers, operators and owners the liabilities include –
• Health and Safety Risk – risk of exposure for employees and the public,
• Site Closure – risk of closing the site until the issue is resolved,
• Reputation Risk – adverse impact on your customer base and company value,
• Legal – risk of prosecution, and
• Financial – risk of civil legal proceedings.
WHERE DOES LEGIONELLA COME FROM?
The preferred areas where legionella pneumophila occur are in pipe systems, pumps and valves, air-cooling systems, air washing units, whirlpools, warm water systems, cold water systems (often due to poor thermal isolation), cooling towers and cooling circuits. They can often be found in retirement homes, hospitals, schools, hotels, public buildings, swimming pools and sport facilities. Old, poorly serviced or seldom used warm water systems and storage devices are areas where legionella can easily grow.
The bacteria multiply to infection level where temperatures are between 20°C and 45°C, but they can survive in lower and higher temperatures. In cold water systems they can appear in summer as result of high outside temperatures and when there is poor isolation of the cold water pipes and the temperatures in the piping become greater than 20°C. The bacteria thrive where there is also a nutrient source and where water flows are low or the water is stagnant.
Legionella can double its population through cell division every three to four hours therefore a build-up of Legionella bacteria can occur quickly.
The presence of biofilm plays a key role in legionella colonisation as it provides nutrition and protection for the legionella bacterium. Biofilm is also the habitat of different single-cell organisms in which Legionella are able to multiply.
HOW THE AQUADRON ADDRESSES LEGIONELLA
The Aquadron treats all of the water that passes through the system, it does this by proportionally dosing all of the water with Anolyte, 24 hours a day, seven days a week. The Anolyte passes through the whole system, removing biofilm and killing bacteria.