The initial step in the prevention of Legionella is a Risk Assessment. The purpose of the Assessment is to enable a valid decision to be made regarding the risk to health. Also, what measures for prevention or adequate control to minimise the risk from exposure to legionella can be taken.

Services and Capabilities

ESP have qualified (BOHS P900 & P901) Environmental scientists and experienced technicians who can carry out your initial Risk Assessment and register upkeep. We are also able to offer guidance and training on what steps/tasks can be taken by your duty holder in order to fully comply with regulations.

The assessment on our site visit will involve an inspection of the water system where both normal running conditions as well as the possible consequences arising from malfunction, breakdown, repair or maintenance of the water systems.
A Risk Assessment is required to ascertain whether the potential for harm to health from exposure is reasonably foreseeable and to ensure that adequate precautionary measures are taken. The assessment will include:
• The potential for droplet formation,
• Whether water temperatures and conditions exist which favour the proliferation of legionella and other micro-organisms,
• The likelihood of aerosol generation,
• The number of people who may be at risk of exposure and the susceptibility of those people,
• Means of prevention or controlling risk.



Our reports clearly lay out all the data collected and the level of risk extrapolated from that with recommendations on steps required to improve areas of medium or high risk.


Our reports are tailored to every individuals requirements, we are happy to chat through the structure if you have specific requirements to best fit in with your company’s profile.


About Legionella
Legionella is a bacteria (Legionella pneumophila) which are common and do occur naturally in the environment in lakes, rivers, streams etc. but usually in relatively small amounts. They have been found in water at temperatures between 6°C and 60°C, however, there is an optimum temperature of between 20°C and 45°C that seems to favour their proliferation. They are normally killed off by temperatures above 60°C but can survive for short periods at temperatures of up to 80°C.

Exposure to legionella can cause legionnaires’ disease in any person but principally affects those with underlying illness, immunosupression, aged etc. Legionnaires’ disease is a potentially fatal form of pneumonia although legionella bacteria can also cause less serious, non-fatal, illnesses grouped by the name legionellosis.


The bacteria must enter the lungs in order to cause infection. Once there, legionella has the potential to cause anything from mild flu like symptoms to a serious or fatal case of pneumonia. Any infection by legionella is not contagious which means multiple cases will have a common point of exposure aiding in identification of the source of infection.


Guidlines indicate water temperature is the simplest and most efficient method of control coupled with regular flushing of any outlets not used on regular basis.

  • Hot water outlets must reach 500C within in 1 minute of running
  • Cold water outlets should be below 200C within 2 minutes of running
  • Boilers should outlet water at 600C

Use of Temperature Mixing Valves for outlets where scalding is a risk – the pipe prior to the TMV can be measured and water should still be able