‘Deep down in the undergrowth of your garden’ is there Legionella…

by Charlie Brain, on 09-05-2019

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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.

With summer on it's way, it;s time for gardeners to think about saving rainwater for their gardens 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 harbor harmful levels of bacteria if not looked after correctly. 

 

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

There is plethora of waterborne bacteria, one of these 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 likes these demonstrate the potentially catastrophic consequences of failing to properly manage and understand the risk from Legionella bacteria.  Making sure the public are aware of the risks of Legionella and the control measures available will go a long way to potentially reducing the risks they may be exposing themselves too whilst enjoying their gardens.

 

Types of Bacteria and Routes to Infection

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. Legionella pneumonophila – 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 is slow moving, where sediment and scale is present, where temperature of the water is between 20°C to 45°C. 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 at Risk?

The Health and Safety Executive have defined those with increased susceptibility of 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. 66 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 middle class, white, female, aged 55+. The latter is most pertinent here when looking at susceptibility.
 

Risks & Control Measure Considerations

For the avid gardeners out there however, there’s no need to be disheartened, increase 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.

 

ITEM ISSUE  CONTROL MEASURE CONSIDERATIONS
Compost
  • Inhalation of compost dust.
Read the health warnings printed in 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 cool environment.
  • Flush direct 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 sprinkling 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.
Ponds
  • 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 / padding. 
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 38-40OC.
  • 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 & PWTAG  

 









 

 

 

 

 

 

 






 

 

 

 

 

 

 

 

 

Summarycb200ltwbkit_1

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 how to operate, maintain and minimise any risks created by them i.e. warning label on the side of bags of compost.

Landlords and Duty Holders should also undertake a Legionellosis Risk Assessment to help minimise the potential risk of Legionnaires’ Disease. 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!

Editors Note: This post was originally published in June 2018 and has been revamped and updated for accuracy and comprehensiveness.

© Water Hygiene Centre 2019

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