Domestic distribution systems

The quality of water in domestic distribution systems can be affected by the appropriate temperature control and regular use of the systems and water fixtures. These measures help prevent growth of Legionella bacteria in particular. Owners of priority premises must prepare a risk assessment for domestic distribution systems to ensure the quality of water and carry out the corrective measures required. Priority premises include buildings in which cases of Legionellosis have been discovered and in which large volumes of water are used or which are used by individuals with an immunodeficiency.

Small amounts of Legionella bacteria and other microbes can access domestic distribution systems through drinking water. Microbes can reproduce in these systems under favourable conditions. Microbes can reduce the water quality, while some of them can cause health hazards. Legionella bacteria are best-known of all pathogens growing in domestic distribution systems. They can cause illnesses especially if they can access the respiratory system through aerosols formed when taking a shower.

Best ways to prevent Legionella bacteria:

  • Keep hot water above 50 degrees and preferably above 55 degrees.
  • Keep cold tap water intended for drinking below 20 degrees.
  • Use all taps regularly, preferably every day.
  • Assess any risks that may lower the quality of water supplied through water systems.

Risk management for domestic distribution systems in priority premises

To secure the quality of drinking water and warm tap water from domestic distribution systems, the owner of the building used as priority premises must gather information necessary for risk management, keep the information up to date, and target risk management measures at domestic distribution systems. The risk assessment and risk management measures must be completed by 12 January 2029.

If required, the municipal health protection authority can issue regulations for building owners or operators who use a building or its part as priority premises. The obligation seeks to prevent illnesses caused by Legionella bacteria.

Priority premises with a risk management obligation include: 

  • units of 24-hour service housing and social welfare units providing institutional care;
  • hospitals and health centres with a ward;
  • spaces intended for accommodation, apart from barracks, as well as furnished apartments and holiday homes offered for accommodation;
  • public spas, indoor and outdoor pools, and saunas.

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