Obligations applicable to buildings’ water systems prevent illnesses caused by Legionella bacteria

The Health Protection Act requires owners of priority premises, as defined in the act, to take care of the quality of water. Owners of premises must assess any risks associated with their building’s water systems and correct any deficiencies identified in the risk assessment.

The obligation seeks to prevent illnesses caused by Legionella bacteria. A risk assessment must be conducted and control measures must be in place by 12 January 2029. However, the National Supervisory Authority for Welfare and Health (Valvira) recommends that risk assessments be started as soon as possible. Building owners must also collect and maintain information about risk assessments. 

Primary premises 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.

Legionella in buildings’ water systems 

Small amounts of microbes such as Legionella bacteria can access buildings’ water systems through water supplied to buildings. Legionella bacteria are best-known of all pathogens growing in water systems, and they can reproduce in these systems under favourable conditions. Legionella bacteria can cause an infection in people, known as Legionnaires’ disease. 

“People can get a Legionella infection by breathing air, which contains droplets with Legionella bacteria, including water vapour. Typically, exposure takes place in the shower. However, Legionella bacteria are not dangerous to people who are otherwise healthy. The risk of a severe infection causing pneumonia is increased by old age, underlying diseases, immunodeficiency and smoking,” Paul Streng says. 

Best ways to prevent Legionella bacteria:

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

You can use Valvira’s checklist for risk assessments (in Finnish)

Read more

Read Valvira’s instructions for risk assessments for buildings’ water systems (in Finnish)
Read more about Legionella bacteria in water systems on the Finnish Institute for Health and Welfare’s website (in Finnish)

Further information

Paul Streng, Senior Officer, +358 295 209 456