Avoid Legionella! How to be sure when you re-open buildings, institutions? – Useful advices to operators

When you re-open buildings and institutions closed down for a longer period of time due to the pandemic special attention should be paid to safe operation and testing of their drinking water pipe works, domestic hot water systems, air handling and air conditioning system.

How to be sure before re-opening of buildings?

  • Microbiological testing of drinking water (in case of drinking water and domestic hot water, testing is recommended to detect micro-organisms able to reproduce intensively in stagnant water: Coliform, Escherichia coli, Germ count at 22°C, Pseudomonas aeruginosa, Enterococcus).
  • Legionella tests (out-of-turn tests are recommended at the monitoring points identified in the Legionella risk assessment process).
  • Air testing (in air handling systems, air conditioning equipment should be tested randomly in accordance with Ministerial Decree No  49/2015. (XI. 6.) EMMI).

What to do to get good results?

  • Ensure water flow (running water, flush all taps for a period of minimum 2 minutes each day, or as long as permanent temperature of the water will have been achieved).
  • Cleaning terminal fittings, descaling (because contamination attached to unused fittings may provide a culture medium and larger surface for the reproduction of bacteria).
  • Regular thermal disinfection of domestic hot water networks (system water temperature to be raised above 70°C for a period of minimum 3 hours, and then flush all discharge points with hot water for three minutes proceeding step by step from the furthermost tapping facility whilst checking water temperature at the same time).
  • Regular air exchange and maintenance of the air conditioning equipment (it has to be provided when operating at a lower head count. Regular ventilation of vacant building parts is recommended additionally).

Health care institutions, commercial accommodations, wet cooling towers and public baths are considered to be facilities of especially high risk. Compliance with the law shall be the responsibility of the operators, or, in lack of operators, the owners of industrial and hospitality industry facilities, public institutions.

Each water system must be operated safely even during the shut down period in order to protect the health of visitors and employees, and the necessary laboratory testing carried out before re-opening.