Legionnaires’ disease is a type of pneumonia that is caused by exposure to water contaminated by Legionella bacteria. Patients usually catch the disease through inhalation of the contaminated water vapour or water droplets. Identified risk zones include old water systems, water fountains, hot tubs and spasswimming pools and water misters that were not sufficiently cleaned and disinfected.

However, there is also a possibility of catching Legionnaires’ disease even away from the obvious suspects of watercourses. New information reveals that people can get it from working in gardens and greenhouses. Standing water in these places can often reach the temperature of 20 to 45 degrees Celsius, which creates the kind of damp, warm environment that attracts the bacteria. 

Another potential risk factor is bagged soil and potting compost, which for the past several years have been the source of reported Legionnaires’ disease cases in Australia, New Zealand, the UK, Japan, the U.S., Switzerland and the Netherlands. The Royal Horticultural Society, however, is quick to say that there is a only a small risk of getting respiratory infections in the garden, and this risk can even get smaller with the application of the right safety measures.  

The Royal Horticultural Society lists the following reminders when working with potting material: 

  • Wear gloves when working with compost, soil, pesticides or fertilisers.
  • Wear a face mask when opening bagged compost or soil. Do not inhale or put your head directly over the opened bag.
  • Store potting materials in areas away from sunlight or high temperature. Hot, sunny places encourage Legionella. 
  • Try to not disturb dust particles when transferring, decanting or working with compost and potting matter.  
  • Read expiration labels carefully to ensure compost is not decaying. Compost should smell sweet and earthy, not sour. 

The following precautionary measures should be taken to avoid Legionella from standing water: 

  • Do not store water in containers that will be left standing for long periods. 
  • Clean watering equipment (bottles, sprays guns, pumps) thoroughly and air dry after use. 
  • As always, wash your hands thoroughly after being in the garden, whether you did some work there or not.

Another step that homeowners and garden lovers should take is to invest in water testing. Testing water systems and sources for disease-carrying bacteria is now easier with our Legionella water testing kits – all you need to do is take a sample and send it back to the service provider for testing. Depending on the results of the test, the testing specialists will provide guidance on the next steps to take in keeping your home and garden safe and disease-free.

+Duncan Hollis