Legionnaires' Standard Legionella Thermometer Kit

Incorrect water temperature is a key risk factor for Legionella growth. The Legionella bacteria multiply in water at temperatures between 20 to 45 °C, particularly if a supply of nutrients is present, such as scale, rust, sludge or algae.

A typical method of control is to store cold water below 20 °C. Hot water should be stored above 60 °C and distributed at above 50 °C. Regular testing using a legionella thermometer helps control legionella risks.

Current legislation means that you must organise a risk assessment if you are an employer or person in control of premises. The revised Approved Code of Practice (ACOP) issued by the Government's Health and Safety Executive (HSE) significantly extends the scope of its guidance on controlling legionella bacteria in water.

The code now applies to all workplace hot and cold water systems regardless of their capacity; the lower limit of 300 litres previously used to exclude domestic systems no longer applies. Whilst domestic systems may represent a risk, the code only applies to risk arising from work activity.

This means all employers managing premises with hot/cold water systems or wet cooling systems are legally responsible for identifying contamination risks and preventing or controlling them.