Landlords and legionella – compliance and control

The aim of this post is to address a few general questions that are often asked regarding legionella control and the duty of landlords, whether commercial or residential.

What is legionella, and what is all the fuss about?

Legionella is a group of pathogenic bacteria that can cause Legionnaires Disease and the lesser forms, Pontiac or Lochgoilhead fevers. Legionnaires’ disease is a potentially fatal form of pneumonia that is particularly harmful to those who are more susceptible to illness due to their age, suffer from other ailments, or if the individual is a smoker or immunosuppressed; however everyone is potentially at risk. To contract the disease, an individual needs to inhale airborne droplets of water containing the bacteria which then need to travel into the lungs.

Where can the bacteria grow?

The bacteria usually live within other microorganisms in natural water sources and presented few problems until man-made environments such as hot and cold water systems presented ideal conditions for the bacteria to grow and disseminate into populated areas. Legionella only needs a few ‘ingredients’ and the correct conditions in order to successfully grow and become problematic:

  • Temperatures between 20 and 45 degrees Celsius
  • Stagnant water (found in storage tanks or in pipework)
  • Nutrients (rust, scale, organic matter, sediment, biofilm [organic slime] etc.)

These conditions are very common in man-made water systems, and can normally be avoided with the implementation of a legionella control management plan, which will be discussed later in the article. On top of having the correct conditions to grow, to present a risk of infection the bacteria also needs a means to disseminate – or be released into the air. While the majority of outbreaks today come from the aerosol generated by cooling towers, many outbreaks have also been attributed to aerosol generated by showers, hoses, and other outlets including taps.

This is all fair enough, but should I really be worried about my properties?

An easy question to answer! Unless you’re qualified, you won’t know, so don’t take the risk!

What do I need to do?

The segment below has been taken from the HSE website and is particularly useful for landlords:

“Organisations, or self-employed individuals, who provide residential accommodation or who are responsible for the water system(s) in their premises, are responsible for ensuring that the risk of exposure to legionella in those premises is properly controlled. This means that they have a duty to assess the risk from exposure to legionella to their staff, residents, guests, tenants and customers by implementing appropriate control measures. This is especially important in residential buildings, where vulnerable people may be at risk, such as retirement flats, or where the accommodation is provided specifically for a group who may be susceptible to legionellosis.” (Health and Safety Executive;

The HSE have produced a document referred to as the ACoP L8 that details how legionella should be controlled in water systems. This can be downloaded for free by using the following link –

What you need to do is get an ACoP L8 compliant risk assessment carried out by a competent company that will assess the likelihood of legionella growing in your water systems under the present conditions. The assessment may put forward some recommendations that would remove or reduce the risk. Here are some basic examples of remedial action that may be identified:

  • Cleaning and disinfecting a water system with biocides
  • Reducing the capacity of a cold water storage tank to prevent stagnation
  • Replacing plant so that WRAS approved materials are used in the design of the water system
  • Removing deadlegs in the pipework

You also need to implement a program to monitoring the water systems to ensure they remain free of conditions that are suitable for bacterial growth. These checks are detailed on page 58 of the ACoP L8 document and should be done in tandem with a contractor.

Give Initial a call and they’ll be happy to help!

Please send your queries via the following link: and a specialist consultant in your area will get in touch. Alternatively, call 0800 077 8963.

This article was provided by Paul Gray from Initial.

This information should not be interpreted as financial advice. Buy to let mortgage rates are subject to change. Speak to our advisors for a mortgage illustration.