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19 July 2017

Legionella prevention plan

How can I prevent legionella?

Why do I need a legionella prevention plan?

The most common reasons for outbreaks of Legionella include poor, or a lack of, preventative measures put in place by those responsible for maintaining water systems. Stakeholders in charge of property maintenance have a legal obligation to comply with legislations - failure to take preventive measures is not only unlawful but can have fatal consequences.

What is legionella?

The bacterium, Legionella pneumophila, is the root cause of legionellosis; the worst form of legionellosis being Legionnaires’ disease. It is considered to be a biological hazard as it is a form of pneumonia. People infected with the disease can suffer from devastating illness and in some instances, death occurs.

Where can legionella grow?

Legionella can grow anywhere where stagnant or warm water exists. However, purpose-built HVAC (heating, ventilation and air conditioning) systems are particularly at risk of causing the disease as they provide the ideal environment for the bacteria to multiply. HVAC systems include:

  • Cooling towers
  • Reservoirs
  • Hot and cold water systems
  • Spa pools
  • Humidifiers
  • Air washers
  • Showers

Environments at risk of dangerous Legionella levels

Large and small sites alike are at risk of Legionella. Establishments particularly vulnerable to the disease include:

  • Homes
  • Hospitals
  • Schools
  • Care facilities
  • Restaurants
  • Hotels
  • Leisure centres / public pools

How can I prevent Legionella?

1) Complete a risk assessment - the first step in the prevention of legionella is to perform a risk assessment. When a risk assessment is performed, it is vital that the following is considered:

  • Temperature - bacteria multiply at temperatures of 20-45ºC. The bacteria lay dormant and do not multiply at temperatures below 20ºC and cannot survive temperatures above 60ºC.
  • Nutrients - impurities such as limescale, algae, sludge or rust act as food for bacteria. Bacteria thrive in warm conditions where nutrients are available.
  • Water storage – Legionella bacteria can multiply when water is stored or if it is re-circulated.
  • Water use in general – the potential threat of Legionella bacteria should be considered if water is likely to be consumed or dispersed (for example, the water used for showers or aerosols).

2) Legionella control – taking measures to prevent the hazards identified in the risk assessment is the next crucial step to prevent Legionella. Control measures include:

  • Ensuring the correct temperatures – ideally at 60ºC or higher to kill the growth of bacteria.
  • Reducing stagnation – removing unnecessary pipes or fittings can help to prevent pools of uncirculated water.
  • Keeping systems clean - cleaning and disinfecting water systems regularly can help to prevent the build-up of impurities.
  • Treatment methods – using water treatments are vital in preventing the growth of Legionella.

3) Legionella testing – testing for Legionella regularly will provide a clear indication of whether the control measures you have already undertaken are working, or whether you will need to perform a more detailed analysis of the infected system to inform the treatment required.

Do you have concerns about legionella prevention? NCH Chem-Aqua can help you.

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