Legionella has been listed on the record of reported illnesses since 1997. Legionella are bacteria that are found everywhere in nature and are therefore unavoidable in water. They are very durable and multiply rapidly in the temperature range of 20 to 45 °C in distinctive biofilms and stagnant water. Legionella cannot be killed until the temperature reaches 70 °C.

These bacteria are dangerous to humans when they emerge in large numbers in shower water and are inhaled in the spray mist. This can result in severe pneumonia which is unfortunately often fatal.


  • Production and distribution facilities for hot water
  • Swimming pools, whirlpools
  • Camping site, sports field and school showers
  • Residential complexes
  • Air conditioners and humidifiers
  • Weekend homes
  • Hotels and accommodation facilities
  • Hospitals, care homes and retirement homes
  • Cooling towers
  • Dead pipes (pipes through which water rarely or never flows).

Do not gamble with your life or the lives of others!

The Royal Decree 865 from 4th July 2003 defines the criteria for hygiene in sanitary areas for the prevention and control of Legionella. Some of these criteria are:

  • The temperature in the hot water tank and/or water heater must be greater than or equal to 60 °C at all times. The return pipes must not fall below 55 °C (see DVGW W551).
  • Long water stagnation periods should be avoided (correct dimensioning of pipe cross-sections and hot water tanks).
  • The water in the pipes must be replaced regularly (dismantling of dead pipes, regular inspection of water consumption or forced flushing).
  • Chalk deposits and encrustations should be avoided.