Cooling Towers

These industrial systems have been most often implicated in major outbreaks. Towers should be individually tested every 3 months (minimum)


Domestic Hot Water Systems

These should be sampled at the hot water cylinder (calorifier) and also at showers, bath and wash hand basin taps.

It's OK to take up to 4 (max) locations on the same system and bulk (mix) them in the same sample bottle. If any one of the locations is contaminated with legionella bacteria, our laboratory will pick it up. Showers and calorifiers (hot water cylinders) are more likely to harbour legionella since they have:-

  • Scale and sediment to provide a habitat and food source
  • Areas where the temperatures are ideal for Legionella growth


Kitchen sinks tend to be used regularly, they are usually a good place to check temperatures and sample for legionella.

Cleaners sinks are often tucked away, out of site - often they become storage areas and the Taps are not run for months at a time. This creates a deadleg area where bacteria, including legionella, can multiply.


As the use of Spas and Jacuzzis increases, so has the incidence of people contracting Legionnaires' Disease. The HSE have released specific guidance for users of this type of equipment.

Follow this link to download the HSE information HSE - Guidance Note for Spa Baths or for full information, follow the link to the Health Protection Agency Management of Spa Pools - Controlling the Risks of Infection

Modern automatic Car Wash plant use powerful pumps which cause substantial spray and aerosols. If the water is contaminated with legionella then the aerosol could effect many people.

Leisure Centres often have Swimming Pools as well as Showers, Jacuzzis and Spas.

It is imperative that a water hygiene regime is in place to ensure the water is safe for the public. Testing for legionella bacteria helps verify that the water hygiene maintenance is working.

Inside smart office blocks/shopping centres or outside in public places, there are decorative Water Fountains and Water Features which release sprays and aerosols. These are sited in areas where lots of people gather together, so if there is contamination - then many people are at risk.