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What are the Legionella regulations for businesses and employers?

Diagram of a water system in a building

We are often asked which aspects of Legionella risk management are best practice for businesses and landlords and what is required by legislation.

There is an ever-present risk of Legionella in any water system. But, it can be managed with sensible Health & Safety measures and by following the available guidance.

The reason Legionella is an ever-present risk is that it is a bacterium. So, in the right environment, in the right conditions, it will multiply.

What is the legislation on Legionella?

There are two laws that need to be considered in relation to Legionella duties:

  • The Health and Safety at Work Act, 1974.
  • The Control of Substances Hazardous to Health Regulations, 2002 (COSHH). This provides legal duties to control the risk from a range of hazardous substances, including biological agents (of which Legionella is one).

And, there are two important pieces of guidance – failure to comply with which is likely to be considered a breach of the law.

  • The L8 Approved Code of Practice (ACOP) of 2001 and republished in November 2013. This document is also known as ‘Legionnaires’ disease: The control of Legionella bacteria in water systems: Approved Code of Practice’.
  • HSG274 Part 2. Those who conduct risk assessments for Legionella (as we do at Environmental Inspection), should do so in accordance with it.

Legal obligations apply to Duty Holders, defined as employers / landlords, those in control of premises, and those with health and safety responsibilities for others. This includes self-employed people who provide services to the public. It also includes landlords, defined as anyone who rents out a home or part of a home. Landlords are included in the Health and Safety at Work Act’s definition of ‘self-employed’ people. For landlords, Section 3(2) of the same act sets out responsibilities to keep tenants safe from hazards.

Does Legionella legislation require water sampling?

Testing or sampling for Legionella (sometimes referred to as microbiological monitoring) is not usually required for commercial or domestic hot and cold water systems, but only in very specific circumstances (HSG274 Part 2, para 2.120).

Testing for Legionella should not be confused with temperature monitoring, which is a reliable method for confirming the water system is under control.

Should you require water testing, this can be arranged by Environmental Inspection, as can the usual risk assessment with temperature monitoring.

Does Legionella legislation require a test certificate?

No. Whilst the risks of Legionella must be managed, Health and safety law does NOT require employers or landlords to obtain or produce a specific certificate. Nor does the Health & Safety Executive (HSE) recognise a ‘Legionella test certificate.’

What should you do about the Legionella risk?

Control of temperature is a large part of the solution. This can be easy or difficult to achieve depending on the complexity of your system.

Building owners / responsible persons are accountable for the effects of any contaminated water within their premises, so risk assessments and temperature monitoring combined with a good general maintenance regime are the minimum requirements. We’ve seen hot water as low as 41°C (when it should be 50°C or more) due to a lack of maintenance checks. The consequences of this can be serious.

How to ensure Legionella regulatory compliance

We would recommend a number of steps to ensure the proper management of Legionella risk and regulatory compliance.

  • Assess the risk. As with most things, compliance can be achieved by contracting a trained and competent professional.
  • Take care in cases where there has not been regular water usage. Water flowing through the system, known as ‘turnover’ is essential for safe water systems. The water must not be allowed to stagnate. Either drain the system before it is left for long periods or flush the system well if not used for a week or more. This is done by letting the water run from your taps for as long as it takes for it to flow through the whole system. This is likely to be a minute or two.
  • Ensure the hot water is at a suitable temperature (above 50°C).
  • Ensure the cold water is at a suitable temperature (below 20°C). Below this temperature, the bacteria are dormant and not replicating. But, they can come back to life when heated.
  • Avoid debris getting into the system (cold water tanks are a key risk for this). The best way is for all tanks to be securely sealed and have a good maintenance regime across the system.
  • Minimise the need for water storage e.g. in tanks.

Depending on the circumstances, there may be a need for specific control measures, such as automatic dosing of biocides or chemicals.
If you are an employer (with 5 or more employees) and you own or rent a workspace, then you must keep a record of your Legionella Risk Assessment. If you are a landlord, there is no legal requirement to do so, but it is prudent because it demonstrates that you have taken the suitable precautions that you are obliged to take.

What are the safe temperatures for hot and cold water systems to prevent Legionella?

Below 20°C (degrees Celsius) for cold water.

Above 50°C (degrees Celsius) for hot water.

How often is a Legionella Risk Assessment required?

It should be repeated whenever it is believed that there is a material change in any of the factors within the management plan, or any of the risk factors for Legionella. This will also include upgrades or additions to the system. Anything that results in a change in temperature, less frequent water flow, the potential for stagnant water, or any part of the system being unused for a week or more.

As a minimum, the hot and cold water system should be assessed for Legionella risks every 2 years.

The risk assessment should also be repeated if there is any reason to believe that the organisation’s duties are not being complied with or the control measures are not adequate.

A change of use of the building, change of system, or change in the responsible person all indicate the need for a new risk assessment.


Need help to ensure your water is safe from Legionella and your compliance? See our Legionella Risk Assessment service.


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