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Legionella Check


What is Legionella and Legionnaires’ disease?

Legionnaires’ disease is a form of pneumonia caused by the legionella bacteria and it is caused by the inhalation of airborne droplets. The symptoms are initially similar to those of flu but in severe cases can develop into pneumonia and there is a fatality rate of approximately 12%.  The bacteria are widespread and outbreaks of the illness occur where water, in pipes, tanks, cooling towers, showers, spa pools, pools and hot water systems in all sorts of domestic premises are maintained at a temperature high enough to encourage growth. Legionella can survive in low temperatures, but thrive at temperatures between 20°C and 45°C, however, high temperatures of 60°C and over will kill them.  Legionnaires’ disease can affect anybody, but some people are at higher risk including those over 45, smokers and heavy drinkers, those suffering from chronic respiratory or kidney disease, and people whose immune system is impaired.

Your responsibility as a Landlord

The legal duty for landlords who provide residential accommodation to consider, assess and control the risks of exposure to Legionella to their tenants is not new. This requirement stems from the Control of Substances Hazardous to Health Regulations 1989; Section 3(2) of the Health and Safety at Work Act 1974 makes provision for the legislation to apply to landlords of both business and domestic premises. All water systems require an assessment of the risk, which they can carry out themselves if they are competent, or employ somebody who is.  In most residential settings, a simple assessment may show that the risks are low and no further action may be necessary. (An example of a typical lower risk situation may be found in a small building (eg: housing unit) with small domestic-type water systems, where daily water usage is inevitable and sufficient to turn over the entire system; where cold water is directly from a wholesome mains supply (no stored water tanks); where hot water is fed from instantaneous heaters or low volume water heaters (supplying outlets at 50 °C); and where the only outlets are toilets and wash hand basins).  If the assessment shows the risks are low and are being properly managed, no further action is needed but it is important to document your findings and ensure that a copy of your assessment is provided to your tenant or managing agent. You must review the assessment regularly in case anything changes in the system.

Precautions which will help control the risk are:

Where showers are installed, these have the means of creating and dispersing water droplets, which may be inhaled causing a foreseeable risk of exposure to legionella. However, if used regularly (as in the majority of most domestic settings) the risks are reduced. In any case, tenants should be advised to regularly clean and disinfect showerheads. Instantaneous electric showers pose less of a risk as they are generally cold water-fed and heat only small volumes of water during operation.

It is important that water is not allowed to stagnate within the water system and so there should be careful management of dwellings that are vacant for extended periods (eg: student accommodation left empty over the summer vacation). As a general principle, outlets on hot and cold water systems should be used at least once a week to maintain a degree of water flow and minimise the chances of stagnation.

To manage the risks during non-occupancy, consideration should be given to implementing a suitable flushing regime or other measures such as draining the system if it is to remain vacant for long periods.

Avoid Legionella

  • Flush out the system prior to letting the property
  • Avoid debris getting into the system by ensuring the cold water tanks, where fitted, have a tight-fitting lid
  • Make sure any redundant pipework is identified and removed
  • Keep water in pipes and tanks below 20°C or above 45°C
  • Make sure that low use systems are flushed through regularly by running taps routinely
  • Keep the system clean to avoid the build-up of sediments which may provide nutrients or harbourage
  • Use a water treatment programme which involves the testing, disinfection and maintenance of the system
  • Ensure that the system is well maintained
  • Allow the shower to run for a couple of minutes before using it
  • Avoid creating unnecessary spray when running taps
  • Swimming pools which appear clean and which have a smell of chlorine are unlikely to be a risk

Tenants should be advised of any control measures put in place that should be maintained eg: not to adjust the temperature setting of the calorifier, to regularly clean showerheads and to inform the landlord if the hot water is not heating properly or there are any other problems with the system so that appropriate action can be taken.

If there are difficulties gaining access to occupied housing units, appropriate checks can be made by carrying out inspections of the water system, for example, when undertaking mandatory visits such as gas safety checks or routine maintenance visits.

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