Evaluation of Legionella regulations in systems for drinking water and warm tap water

The aim of this project is to determine whether current scientific understanding justifies amendments to the regulations on Legionella prevention in mains water systems and, if so, how modifications should be made to the prevailing regulations.

Legionella prevention in mains water systems

The growth of Legionella in water systems poses a potential threat to public health. When people inhale a pathogenic strain of the Legionella bacterium, there is a risk of legionnaires’ disease (legionellosis). The symptoms can vary from flu-like symptoms to severe pneumonia. Because pathogenic Legionella strains can grow in mains water and therefore pose a threat to public health, there is legislation in place in the Netherlands for controlling their growth in mains water systems.

The current legislative framework is still based on thinking from 2000. Legionella has been extensively studied since then. The scientific consensus about how Legionella propagates in mains water systems and about the effectiveness of control measures (such as flushing with hot water) has changed.

New scientific understanding

Berenschot and KWR are looking into the question of which existing regulations for Legionella prevention in systems for drinking water and hot water need to be adapted in the light of current scientific understanding, and how. Answering this central research question results in the following three sub-questions, which will be addressed in this project:

  • Which current insights into Legionella prevention justify amendments to the regulations in place, and why?
  • What are the strengths and weaknesses in theory and practice of the current regulations, and why?
  • How can the content of the existing regulations on Legionella prevention be amended?

More effective and targeted regulations for the future

The project is being managed by a committee with different stakeholders, such as the Dutch National Institute for Public Health and the Environment, the Legionnaires’ Disease Foundation, Envaqua and Techniek Nederland. It will result in a report with a scientific section and a legal-administrative section that will be presented to the Dutch Lower House and constitute the basis for amendments to Legionella regulations in the coming years. It is expected that this will lead to more effective and targeted regulations for Legionella prevention in mains water systems and improve the enforceability of the legislation in practice.