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Legionella & Water Quality

What is legionella?

Legionella is a bacterium which can lead to diseases known as legionellosis. Legionnaires’ disease is a potentially fatal pneumonia caused by legionella bacteria and It is the most well-known and serious form. Other similar (but usually less serious) conditions include Pontiac fever and Lochgoilhead fever.

How can infection occur?

Infection is caused by breathing in tiny droplets of water (an aerosol) contaminated by the bacteria. The disease cannot be passed from one person to another.

Everyone is potentially susceptible to infection but some people are at higher risk, eg those over 45 years of age, smokers and heavy drinkers, those suffering from chronic respiratory or kidney disease, and people whose immune system is impaired.

Legionella bacteria are common in natural water courses such as rivers and ponds. Since legionella are widespread in the environment, they may contaminate and grow in other water systems such as cooling towers and hot and cold water services.

They survive low temperatures and thrive at temperatures between 20-45°C if the conditions are right, eg if a supply of nutrients is present such as rust, sludge, scale, algae and other bacteria. Hence stored water poses the highest risk. The bacteria are killed by high temperatures.

There are no cooling towers at the University and water is generally supplied direct from the mains, this minimises the risk of infection.

The water distribution systems across the campus including the control of legionella are managed by the Estates Office.

However there are other places where legionella can grow. Water in car windscreen reservoirs can provide an environment for legionella bacteria to grow, but using screenwash in the correct concentrations will reduce its proliferation. Similarly small desk humidifiers which contain water reservoirs which sit at room temperature can provide an ideal environment for bacterial growth. If these are not subject to routine cleaning and water changing they could release harmful bacteria into the air; for this reason these are not permitted in a workplace.

When using jet washers ensure that they are rinsed through when connecting up and before swithching on the jet - this will allow any stagnant water to pass through the jet.