Water safety


  1. Legionnaires' disease
  2. Reducing the risk of Legionella in your home
  3. Reducing the risk of Legionella in your garden

Legionnaires' disease

Under the right conditions harmful Legionella bacteria can increase in numbers resulting in an increased risk of Legionnaires' disease, a potentially fatal form of pneumonia.

This can affect anybody, but there are a number of factors that increase susceptibility.

These include:

  • people over 45 years of age
  • smokers
  • people suffering from chronic respiratory or kidney disease
  • anyone with an impaired immune system

Legionella bacteria are most commonly found in soil and natural water courses, such as rivers.

It can also occur in man-made water systems which include hot and cold water storage tanks, pipes and garden hoses.

It can survive low temperatures, thrives at temperatures between 20°C and 45°C, but is killed by high temperatures of 60°C and over.

Although usually associated with larger water systems in offices, hotels and hospitals, Legionella bacteria can also be found in the smaller systems associated with domestic properties.

Legionnaires' disease cannot be caught drinking contaminated water. To be harmful the bacteria must be inhaled within an aerosol.

The symptoms of Legionnaires disease are similar to those of flu:

  • high temperatures
  • fevers or chills
  • headaches tiredness
  • muscle pains

Reducing the risk of Legionella in your home

It is important to understand that the risk of Legionella causing illness in small domestic properties is extremely low.

The biggest risk possibly being when you have been away from your home for more than a week, resulting in a build-up of stagnant and potentially contaminated water in the pipework.

This may be due to long hospital admissions, periods of respite or extended holidays.

When returning to your home to help reduce any risk you should therefore:

  • run all taps for at least 5 minutes taking care not to produce an aerosol.
  • run showers for five minutes on both high and low settings having first removed or placed the shower head in a bucket to reduce aerosol.
  • flush toilets twice with the lid down to circulate fresh water through the system and empty the cistern.
  • set the thermostat to 60°C if your system maintains stored hot water although care is required for older persons and children to prevent the risk of burns and scalding.
  • set your Combi-boiler thermostat to 50°C.

Showers and taps should also be cleaned of scale and debris every 3 months or earlier if required.

Reducing the risk of Legionella in your garden

Garden hoses can pose a risk, especially if they have been stored in the sun without having been drained.

We recommend completely draining the hose after use and storing it out of direct sunlight where possible.

Water butts should be regularly drained and cleaned to prevent bacterial build up.