Could there be Legionella risk in your garden?

by Charlie Brain, on 22-05-2024
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Legionella Risk in Gardens

In today’s world people are trying to save money, lead healthier lifestyles, eat healthier foods and be more active. Many people take pride in their gardens and use gardening to help with healthier lifestyles by growing their own healthy foods and enjoying the fresh smell of flowers.

Can gardening equipment harbour Legionella?

Leading up to the summer months, many gardeners think about saving rainwater for their garden’s thirstiest months. It is a little-known issue, but neglect and misuse of our gardening equipment can represent health risks in the form of waterborne bacteria and diseases. Water butts, hose pipes, ponds and even compost can all harbour harmful levels of bacteria if not looked after correctly. 


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In this blog, we look at some of the issues with gardening equipment and other devices used/found in the garden and what might be done to reduce the risk of exposure to soil and waterborne bacteria.


Why is it important to regularly maintain your gardening equipment?

There is a plethora of soil and waterborne bacteria, one type of bacteria is ‘Legionella’. Exposure to Legionella can cause Legionnaires’ disease. In recent times, there have been reported cases of Legionnaires’ disease linked with gardening activities, for example;

Articles like these demonstrate the potentially catastrophic consequences of failing to properly manage and understand the risk of Legionella bacteria.  Making sure the public is aware of Legionella risk and the control measures available will go a long way to potentially reducing the risks they may be exposing themselves to whilst enjoying their gardens.


What types of Legionella can be found in gardening equipment?

With all gardening-related activities, there are 2 types of Legionella bacteria that have been reported within the UK;

  1. Legionella longbeachae – this is not common but can be found in potting mixes, compost heaps and composted animal manures. Respiratory disease can develop after inhaling dust from contaminated compost;

  2. Legionnaires Disease up close  Legionella 750x499Legionella pneumophila – this is more common as the bacteria forms naturally in watercourses but will multiply in purpose-built water systems. Where these systems are allowed to stagnate or are slow moving, where sediment and scale are present, and where temperature of the water is between 20°C to 45°C, provides ideal conditions for waterborne pathogens to proliferate. Inhalation of water aerosols [sprays] is the route of infection. The source of which can be hoses/sprinklers, outside taps, hot tubs and water features/fountains. This type of bacteria accounts for 90% of Legionella cases in the UK.

Who is most at risk from Legionella?

The Health and Safety Executive (HSE) have defined those with increased susceptibility to developing an illness caused by Legionella bacteria as;

  • People over 45 years of age;

  • Smokers and heavy drinkers;

  • People suffering from chronic respiratory or kidney disease;

  • Diabetes, lung and heart disease;

  • Anyone with an impaired immune system.

The UK population is approx. 67 million, of which approx. 27 million people partake in gardening. What is the demographic of these gardeners…. many sources state that the typical gardener is female, aged 55+. The latter is most pertinent here when looking at susceptibility.

What control measures should be put in place to reduce Legionella risk in your garden?

For the avid gardeners out there, there’s no need to be disheartened, increased awareness of your surroundings and the risks present and by considering some simple control measures your biggest problem will be waiting for the dry spells to entertain your green fingers.





  • Inhalation of compost dust.

Read the health warnings printed on the side of bags of compost. Namely:

  • Dampen dry composts before use.
  • Avoid opening bags with your head right over them. 
  • Avoid using/potting up in confined spaces. 
  • Store opened bags in a cool environment and seal openings. 
  • Wear dust masks.

Hose Pipes & Flower Bed Irrigation Systems

  • Stagnant water left within hose pipes that are not frequently used. Where they are left in direct sunlight temperature gain is an added issue.
  • Empty hoses when not in use, coil up and store in a cool environment.
  • Flush directly to drain or cover the end of the hose when using for the first time after a period of non-use i.e. 5-7 days. 

Water Butts

  • Can contain dirty/contaminated water (from roofs & gutters) which often stagnates where they’re not frequently used. 
  • Temperature gains when located in direct sunlight.
  • Empty and clean annually. 
  • Insulate to avoid heat gains in warmer weather or paint in a light colour to reflect the heat.
  • Do not use for sprinkler systems.

Outside Taps

  • Stagnant water contained within pipework during colder times of year (seasonal use).
  • Flush taps regularly, at least weekly.
  • Ensure taps are fitted with check valves to prevent contamination re-entering the property.


  • Can be considered as a stagnant body of water. 
  • Prone to heat gains during warmer months. 
  • Pond-life will introduce additional contamination.
  • Avoid installing water fountains that create significant aerosol, particularly where ponds are located in warm areas.
  • Consider fencing off the pond area if small children are around.
  • Do not use pond water for recreational purposes/swim/paddling

Water Features

  • Create aerosols continuously from the same body of water. 
  • Temperature gains in warmer months. 
  • Clean and disinfect spray heads and make-up tanks as required (potentially at least once a year). 
  • Avoid locating beneath trees.
  • Avoid locating in areas exposed to high winds.
  • Avoid fitting a jet that creates excessive aerosol.

Horticultural Misting Systems

  • Creates an aerosol and often used with hose pipes. Can at times be found within an enclosed space i.e. green house/poly tunnel.
  • Clean and disinfect distribution pipework, spray heads and make-up tanks at least quarterly.
  • Where the system is not in use then flushing through at least weekly. 

Spa Pools / Hot Tubs

  • Contaminated pool water.
  • Operating water temperatures of around 38-40 Deg C.
  • High aerosol release.
  • Exposure given proximity of users.
  • Should be maintained according to manufactures instructions to ensure water quality.
  • Detailed information and instruction via HSE (HSG282) & PWTAG  


Legionella Water Butt

Gardeners should be aware of potential risks associated with gardening equipment/devices found/used in the garden.

Like any product, individuals should ‘always read the label’ for advice on how to operate, maintain and minimise any Legionella risks created by them i.e. warning label on the side of bags of compost.


Landlords and Dutyholders should also undertake a Legionella Risk Assessment to help minimise the potential risk. By increasing awareness of these risks and sharing of information we can all help to reduce the amount of exposure to Legionella, and beat the micro beasties lurking in our gardens!

If you have queries or concerns regarding the above or you would like to speak to a member of the team please click here to get in touch.

Editors Note: The information provided in this blog is correct at the date of original publication – May 2019 (Revised May 2024)

© Water Hygiene Centre 2024

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About the author

Charlie Brain

Charlie started the Water Hygiene Centre as a trainee risk assessor back in 2010, since then he has developed professionally from risk assessor, project manager and is now a Senior Consultant. During this time he has taken ownership of our risk assessment method and development of our bespoke reporting platform and has been key in our UKAS accreditation to 17020.

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