Legionella and garden soils

Commercial garden soils which include packaged potting mixes and bulk soil supplies have been associated with several cases of Legionnaires’ Disease in WA, as a result of exposure to the bacteria Legionella longbeachae.

How Legionella longbeachae are spread is uncertain, but it is thought that they are breathed in or spread from hand to mouth. The bacteria can remain on hands contaminated by handling potting mix and other garden soils

This public health risk is currently managed under the Health (Garden Soil) Regulations 1998, (Garden Soils Regulations) which requires warning labels to be included on packaged materials or for signage to displayed in prominent locations at bulk soil suppliers.

The Garden Soil Regulations are currently under review as part of the Public Health Act 2016 regulation review program.

Garden soils, as defined by the Garden Soils Regulations, include:

  • potting mixes
  • gardening soils
  • mulches
  • composts and
  • soil conditioners.

Package, in relation to garden soil, means anything that contains or surrounds the garden soil, whether or not the garden soil is completely enclosed.

Currently, no strategies are available to control or eliminate Legionella longbeachae growing in commercial garden soils. Soil in the natural environment may still present a risk when people are working in their gardens.

Preventative strategies for this disease are limited to educating the community on the safe use of garden soils, which includes publishing health warnings on bagged materials and providing signage near bulked products. Such warnings attempt to inform the consumer to take precautionary measures when handling garden soils.

These recommendations include:

  • using a face mask
  • wearing gloves
  • avoiding inhalation of dust and aerosols and
  • washing hands after using the material.