Landlord Legionella Risk Assessment: Everything You Need To Know

Landlords must carry out a legionella risk assessment on their properties to ensure they're safe and habitable. Here's what you need to know.

Property Maintenance

There are a number of ever-changing compliance regulations landlords have to keep on top of, from electrical regulations, gas safety, and EPC requirements to the new MTD for ITSA coming in in 2026. But what’s the deal when it comes to water?

In this article, we take a close look at landlord responsibilities around water, the risks of Legionella, how to run a Legionella risk assessment, and what you need to do to keep your water and your tenants safe.


It is a legal requirement for landlords to carry out risk assessments on their properties to assess the potential risk of exposure to legionella. This risk assessment must consider the domestic hot and cold water systems, water tanks, water heaters, and the water temperature.

The 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. Landlords do not need to get a formal certificate and can carry this work out themselves if they are competent, or otherwise employ somebody else to do so.

What is Legionella?

Legionellosis or Legionnaires’ disease is caused by ingesting common Legionella bacteria and is an infectious and sometimes fatal form of pneumonia. Legionella bacteria generally live in soil, compost, potting mix, and is commonly found in water systems (for example, spa pools, and hot water tanks). Legionella thrives between temperatures of 20°C to 45°C degrees.

Hot and cold water systems are an ideal environment for Legionella to grow in. The risk of contamination is particularly high in:

  • Water tanks and systems in which water is stagnant and/or recirculated
  • Water droplets or aerosols produced by whirlpool baths or showerheads
  • Mist and spray dispersed into the air
  • Rust, scale, sludge, and biofilm that “feed” the bacteria
  • Properties that are left empty for a long period of time

The risk of Legionella is low in properties with combi boilers, as the system keeps the water moving – giving the bacteria little chance to develop.

However, homes with open water tanks (usually older buildings) have a substantially higher risk of Legionella, as the water is more likely to be left to stagnate.

About Legionnaires’ disease?

Legionnaires’ disease can develop into a serious and even life-threatening illness. Common symptoms include:

  • High temperature
  • Coughing
  • Shortness of breath
  • Headaches
  • Nausea

The symptoms of Legionnaires’ disease usually last between 2 to 10 days and can be treated with antibiotics. Some people are particularly vulnerable to the risks of Legionella, including older people, those with lung issues, and poor immune function.

testing legionnaires assessment (1)

What does a landlord Legionella risk assessment involve?

A Legionella risk assessment will generally cover all water systems in your rental property. The assessment itself will involve:

  • Identifying potential hazards and the level of risk posed
  • Identifying who is at risk
  • Testing the water system for Legionella*
  • Putting adequate control measures in place to minimise the risk
  • Recording the findings of the assessment
  • Reviewing the assessment as needed

*Testing or sampling water for Legionella bacteria is not a legal requirement for landlords but is typically part of a Legionella risk assessment carried out by a professional.

A Legionella risk assessment should be carried out by someone with a competent understanding of the hazard of Legionella.

How often should landlords carry out a Legionella risk assessment?

The regularity of the Legionella risk assessment is really down to the property. or properties with water systems that are more likely to pose a Legionella risk, it is recommended that a risk assessment is carried out once every two years – or before a new tenancy begins. It’s also a good idea to perform a risk assessment if there are significant changes to the property’s water systems.

Should you get a professional Legionella risk assessment?

A professional risk assessment is not a formal legal requirement, however, it’s an excellent way to ensure your water supply is safe.

There is also the element of time an assessment will take, so depending on the size of your property you might choose to outsource the work.

A professional Legionella risk assessment will inspect a variety of aspects including:

  • A digital temperature reading of every hot and cold tap on the property and reading of outlet pipes from water tanks.
  • Visually inspect every tap and showerhead,
  • Report on redundant pipework, flexible hoses, and outdoor hoses
  • Access and report on any water tanks in the loft.
  • If the property has a garden with an exterior tap, it must be tested for limescale.

As such, a one-bed flat with a combi-boiler wouldn’t have many of the elements needed to inspect and may take as little as twenty minutes. On the other hand, a larger property with a garden, multiple bathrooms, and a hot and cold tank would take significantly longer, an hour or more.

How can landlords minimise the risks of Legionella?

There are a variety of things that can be done and are recommended by the Health and Safety Executive to help reduce the risk of Legionella disease in buy-to-let properties. These measures include:

  • Flushing out the water system before the property is let (and once a week during void periods).
  • Ensuring systems and tanks are soundly and tightly fit to avoid debris getting in.
  • Setting control parameters, such as setting the temperature of the hot water cylinder to ensure hot water is stored at 60°C.
  • Removing any faulty or redundant pipework.

The above controls are the landlord’s responsibility, but tenants should be notified of any measures in place and be advised to:

  • Notify the landlord if there are problems with the water system (such as the hot water not working)
  • Not adjust set temperature parameters
  • Regularly clean and disinfect showerheads

What other inspections and assessments do landlords need to carry out?

As a landlord, you should:

If you fail to arrange your required inspections or fail to give your tenants the correct documents, you could be subject to hefty fines and may invalidate your right to issue a Section 21 notice to your tenant.

You Might Like