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Keeping the hospital legionella-free in Munich, Germany

University Hospital,
Munich, Germany

The Grosshadern site of Munich’s University Hospital is a 13-floor complex built in the 1970s. It uses 64,000 cubic metres of hot tap water annually. The tap water network consists of some 200 km of piping and more than 7,000 tap outlets. With today’s standards, the pipes are over-dimensioned and the network has repeatedly been altered and added to.

Legionella threat

Like every hospital, the Grosshadern clinic needs to keep its patients and staff safe from legionella bacteria in the hot tap water. The extensive network made it difficult to correctly assess the temperature drop (and thus increased bacterial risk) in every remote corner of the system. Specific preventive technical measures were required to ensure a permanent supply of legionella-free tap water everywhere.

Anti-legionella system

In the hospital’s twelve technical centres, the water-heating equipment has been renewed. Old water tanks have been replaced with Alfa Laval’s anti-legionella system AquaProtect-T. It is designed for thermal disinfection of hot water, to eliminate legionella. Only disinfected water now goes into the network. Thanks to effective heat recovery, the thermal disinfection process consumes virtually no extra energy.

Heat exchangers

In addition to eliminating legionella throughout the entire hospital, the AquaProtect-T system provided several significant energy savings. In each technical centre, rather than keeping multiple 5,000-litre storage tanks heated, the flow is now heated and disinfected in a two-stage process using compact heat exchangers.

Facts and figures:

  • The University hospital uses 64,000 m3 of hot water annually.
  • The total pipe network is 200 km long with over 7,000 tap outlets.
  • Alfa Laval’s AquaProtect T was installed for thermal disinfection.
  • The disinfection process runs once a week at night for four hours.
  • The AquaProtect system provides a quarter of the clinic’s drinking water.
  • It replaced six hot water tanks, each holding 5,000 litres.