Legislation and guidelines relating to legionellae

Instructions for housing

• Government Decree on Household Water

  The quality of the water intended for human consumption is generally governed by the Decree of the Ministry of Social Affairs and Health on the Quality and Monitoring of Household Water and the Risk Management of Water Systems of Buildings (STMa 1352/2015). According to this decree, micro-organisms, parasites or other substances must not be present in household water in quantities or concentrations that may pose a risk to human health. The action threshold for Legionella concentration in household water and domestic hot water referred to in the Decree is 1000 cfu/l (entry into force on 12 January 2023).
  Government Decree on Household Water (1352/2015) (Finlex, in Finnish)
   

• Health Protection Act

  According to the Health Protection Act (763/1994), there must not be present in an apartment or other living area quantities of microbes that would be harmful to human health. The municipal health authority may oblige the person whose actions or measures are the cause of such a deficiency to take measures to eliminate or limit the adverse health effects.

  Based on the amendment to the Health Protection Act that entered into force on 12 January 2023, risk assessments of water systems must in future be conducted in priority premises. Such premises include sites such as hospitals, swimming pools and hotels. In the risk assessment, information on the building’s water system is used to assess whether the risk for the presence of Legionella has increased.

  Health Protection Act (763/1994) (Finlex, in Finnish)

• Water and Drainage Decree

  The Ministry of the Environment’s Decree on Water and Drainage Systems in Properties (YMa 1047/2017), which relates to both new construction and renovation, states the following:

  • The cold water pipeline shall be so designed and installed that the temperature of the water shall not exceed 20 °C. When left unused for periods of less than 8 hours, the temperature of the water shall not exceed 24 °C.
  • The water temperature in the hot water system shall be at least 55 °C and shall be obtainable from the fixtures within 20 seconds.
  • Water from hot water fixtures shall not exceed 65 °C.

  In Finland, the minimum temperature requirement of 55 °C for domestic hot water has already been in force since the introduction of the previous legislation on the matter (the Finnish Building Code D1) in 2007.

  Government Decree on Water and Drainage Systems in Properties (1047/2017) (Finlex, in Finnish)
   

• Housing Health Decree

  For hot water systems built before 2007, the Housing Health Decree of the Ministry of Social Affairs and Health (STMa 545/2015) contains a provision on the temperature of hot water: The temperature of warm tap water from a hot water system shall be at minimum +50 degrees Celsius, and the temperature of water from a plumbing fixture may be at most +65 degrees Celsius.

  The application directives for the Housing Health Decree state that the minimum temperature of 50 °C is specifically intended to prevent the growth of Legionella bacteria by requiring that all parts of the water pipeline maintain this temperature, including the final section of the water system (the tap of the end user). The temperature requirement does not only apply therefore to the temperature of the water leaving the hot water accumulator.

  The temperatures in the plumbing sections may be lower than the prescribed value when not in use and also in exceptional situations where, for example, the hot water accumulator is unable to produce sufficient hot water due to heavy water consumption. However, the hot water system must operate in such a way that, under normal conditions, the required temperature level is obtained in all parts of the water system.

  In new construction and renovation projects, the design work most aim towards a minimum temperature of 55 °C. The maximum temperature requirement of 65 °C applies, in particular, to the temperature of water from hot water fixtures (water taps) intended for personal cleaning. This is in order to prevent accidents (burn) and damage to materials. Elsewhere in the hot water system, temperatures may be higher than this value.

  Domestic hot water from hot water systems must always be at least 50 °C. Intermittent superheating of water does not meet this requirement if the water temperature at any point in the cycle is less than 50 °C.

  Decree of the Ministry of Social Affairs and Health on Health-related Conditions of Housing and Other Residential Buildings and Qualification Requirements for Third-party Experts (Housing Health Decree 545/2015) (Finlex)

  Application directives for the Housing Health Decree (Part I) (Valvira, pdf 253 kB, in Finnish)

• CEN Instructions

  The CEN Instructions for Finland (CEN/TR 16355) published by the Finnish Federation for Standardisation (SFS) recommends the following temperatures for cold household water and domestic hot water  in order to prevent the growth of legionellae:

  • Cold household water temperature should not exceed 25 °C.
  • In the hot water system, the temperature at each water point should be at least 55 °C during normal operation. If the system is equipped with a circuit section, the temperature of the water should reach 60 °C within 30 seconds of the opening of the water point.

  CEN/TR 16355, Recommendations for prevention of Legionella growth in installations inside buildings conveying water for human consumption (SFS Standard webstore)
   

• Instructions relating to indoor air and ventilation

  The Decree of the Ministry of the Environment on Indoor Air and Ventilation of New Buildings (YMa 1009/2017) stipulates the following:

  • Indoor air shall not contain particulate impurities, physical, chemical or microbiological agents, or odours that continuously impair the pleasantness of the environment.
  • Exhaust air shall be removed from the building in such a way that no harm to health nor any other harm is caused to the building itself, to other buildings, to the environment or to the users of the above. 
  • The connection of the ventilation ducts must not pose a risk of spreading contamination nor impede the operation of the ventilation system.
  • If the ventilation system features air humidification, the humidification of the air must be designed in such a way as to avoid conditions for the growth of microbes that endanger health.

  Decree of the Ministry of the Environment on Indoor Climate and Ventilation in New Buildings (1009/2017) (Finlex, in Finnish)
   

Instructions for workplaces

• Occupational Safety and Health Act

  The Occupational Safety and Health Act (738/2002) stipulates that an employee's exposure to biological agents that cause harm or danger to safety and health must be limited to such a degree that these factors do not cause any harm or risk to the employee's safety, health or reproductive health.
  Occupational Safety And Health Act (738/2002) (Finlex)

• Government Decree on the Protection of Employees

  The purpose of the Government Decree based on the Occupational Safety and Health Act (VNa 933/2017) is to protect employees from hazards caused by biological agents connected with their work. Legionellae belong to category 2 in the classification of biological agents, meaning that they are biological factors that can cause illness to humans and can therefore be dangerous to employees. According to the classification, they are probably not spreading through the population, and effective prevention and treatment measures are usually available for tackling them.
  Government Decree on Protecting Workers from Risks Arising from Biological Agents (933/2017) (Finlex, in Finnish)

  See also the Decree of the Ministry of Social Affairs and Health on the Classification of Biological Agents (STMa 921/2010) and the attached classification of biological agents.
  Decree of the Ministry of Social Affairs and Health on the Classification of Biological Agents (921/2010) (Finlex, in Finnish)
   

Instructions for ships

• Finnish national application directives for the inspection of ships and issuance of ship sanitation certificates

  The national application directives for the International Health Regulations (IHR) prepared by the WHO can be found on the website of the National Supervisory Authority for Welfare and Health (Valvira). According to these instructions, the water temperature on ships should be either below 25 °C or above 50 °C. If the temperature is between 25 °C and 50 °C, there is a high risk of Legionella bacteria growing, and the safety of the water should therefore be investigated by analysing the quantity of Legionella bacteria present.
  WHO’s Handbook for Inspection of Ships and Issuance of Ship Sanitation Certificates, Finnish national application directives (National Supervisory Authority for Welfare and Health Valvira, pdf 2.6 MB, in Finnish)

Instructions for recreational facilities

• Health Protection Act

  According to the Health Protection Act (763/1994), campsites or other similar areas reserved for accommodation use as well as outdoor or indoor swimming pools, beaches, spas, saunas or other similar areas or facilities intended for public use must be designed, equipped, maintained and managed in such a way as to prevent harm to the health of those spending time there.
  Health Protection Act (763/1994) (Finlex, in Finnish)

• Pool Water Decree

  According to the Pool Water Decree of the Ministry of Social Affairs and Health (STMa 315 / 2002), no micro-organisms, parasites or any substances may be present in the pool water in quantities that may be harmful to human health. Pool water shall meet the quality requirements set out in the Annex to this decree and shall also be otherwise suitable for the purpose. The microbiological quality of pool water shall be ensured primarily by disinfecting the water with chlorine.
  Decree of the Ministry of Social Affairs and Health on Quality Requirements and Supervision Studies for Pool Water in Swimming Pools and Spas (315/2002) (Finlex, in Finnish)

  Valvira's application directives also contain more detailed information on legionellae in the pool water environment. Legionellae must not be present in pool water of a good quality.
  Application directives for the Pool Water Decree (National Supervisory Authority for Welfare and Health Valvira, pdf 2.1 MB, in Finnish)

International cooperation work underpinning the guidelines

• Collaboration in preventing cases of legionellosis

  Cooperation between different countries is carried out to detect and prevent cases of legionellosis and to solve problems relating to studies of clinical and environmental samples. Finland also participates in international cooperation to prevent legionellosis.

  In 2012, the ESCMID Study Group for Legionella Infections (ESGLI) was established to continue the work of the European Working Group for Legionella Infections (EWGLI) that had been operating since 1986.
  Legionella infections (ESGLI)

  Since 2009, the monitoring of Legionnaires’ disease has been the task of the European Legionnaires' Disease Surveillance Network (ELDSNet), which is part of the European Centre for Disease Prevention and Control (ECDC). All cases of Legionnaires’ disease detected in Finland are reported to ELDSNet. In the monitoring of the disease, special attention is paid to legionellosis cases among tourists.

  Further reading:

  • European Legionnaires’ Disease Surveillance Network (ELDSNet, ECDC)
  • Information on Legionnaires’ disease for managers of tourist accommodation (downloadable from ECDC's website)

• EU Drinking Water Directive (2020/2184)

  The EU Drinking Water Directive (2020/2184), which entered into effect on 12 January 2021, contains obligations relating to legionellae. These obligations were included in Finland's legislation on 12 January 2023.

  A risk assessment of the water system of a property must be conducted on priority premises in which a large number of people may be exposed to risks caused by water. In the risk assessment, especially the risks to the consumer of water stemming from legionella and the products and materials used in water systems are assessed.

  The risk assessments of water systems of properties must focus on the priority premises defined by the Member States. In Finland sites such as hospitals, hotels, swimming pools and spas have been defined as priority premises. The legionella concentration of water used in properties must be less than 1000 cfu/l.
  Directive (EU) 2020/2184 of the European Parliament and the Council on the quality of water intended for human consumption (EUR-Lex, pdf 858 kB)

• Investigations and prevention of infections in Europe

  The Legionella instructions published by ECDC contain a report on the monitoring of Legionella infections:
  European Legionnaires’ Disease Surveillance Network (ELDSNet) - Operating procedures (ECDC)
   

• ESGLI guidelines

  The European technical guidelines for Legionella contain guidance and concentration limits in accordance with which Legionella control measures should be carried out.
  ESGLI European Technical Guidelines for the Prevention Control and Investigation of Infections Caused by Legionella species June 2017 (ESCMID, pdf 1840 kB)

  As a result of the COVID-19 pandemic, the water quality in the water systems of closed hotels and unused ships may deteriorate because there is an increase in inactivity without a corresponding increase in cleaning measures. ESGLI has produced its own guidelines on this topic regarding the prevention of legionellosis cases through the cleaning of water systems prior to redeployment.
  ESGLI Guidance for managing Legionella in building water systems during the COVID-19 pandemic (ESCMID, pdf 83 kB)

  Further reading: Combating the risk of Legionella during an interruption in the use of water systems

  Due to COVID-19 infections, effective control of Legionella bacteria should be ensured to prevent secondary infections in patients in hospital and healthcare facilities. ESGLI has developed guidelines for hospitals and healthcare facilities to reduce the risks of legionellosis arising from the COVID-19 pandemic:

  • ESGLI Guidance for managing Legionella in hospital water systems during the COVID-19 pandemic (ESCMID, pdf 188 kB)
  • ESGLI Guidance for managing Legionella in nursing & care home water systems during the COVID-19 pandemic (ESCMID, pdf 162 kB)

  During the COVID-19 pandemic, the longer term inactivity of dental care equipment can increase the Legionella content in their water systems. Even during normal use, the water in dental care equipment circulates relatively slowly, which can easily result in increased microbial concentrations. Therefore, during the COVID-19 pandemic, special care should be taken to ensure dental care equipment hygiene in accordance with either the cleaning instructions provided by the device manufacturer or the ESGLI guidelines, which recommend that the effectiveness of cleaning measures should be determined using a water sample, and that the equipment should be brought into use only if the results of this are sufficient (Legionella content < 100 cfu/l).
  ESGLI Guidance for managing Legionella in dental water systems during the COVID-19 pandemic (ESCMID, pdf 202 kB)

  Further reading: ESGLI: Legionella infections

• Guidelines for ships

  According to the International Health Regulations (IHR) and the handbook for the inspection of ships produced by the WHO, the water temperature should be either below 25 °C or above 50 °C. If the temperature is between 25 °C and 50 °C, the risk is high for the growth of Legionella bacteria, and the safety of the water should therefore be investigated by analysing the quantity of Legionella bacteria present in the water. The national application directives can be found on Valvira's website.

  • Handbook for Inspection of Ships and Issuance of Ship Sanitation Certificates (WHO)
  • WHO’s Handbook for Inspection of Ships and Issuance of Ship Sanitation Certificates, Finnish national application directives (National Supervisory Authority for Welfare and Health Valvira, pdf 2.6 MB, in Finnish)

  According to the WHO guide, which contains more precise concentration limits, the Legionella content of water systems on board ships should be less than 100 cfu/ 100 ml, which is less than 1000 cfu/l.
  Guide to ship sanitation (Table 2-2) (WHO, pdf 3 MB)

  Instructions related to the hygiene of water systems on ships:
  European Manual for Hygiene Standards and Communicable Disease Surveillance on Passenger Ships (Shipsan project)
   

• WHO Guidelines

  The WHO has published several guidelines related to Legionella bacteria in different kinds of water systems.

  Drinking water quality:
  Guidelines for drinking water quality, fourth edition incorporating the first addendum (WHO)

  Safety of water systems in buildings:
  Water safety in buildings (WHO, pdf 785 kB)

  Legionellae and the prevention of legionellosis:
  Legionella and the prevention of legionellosis (WHO, pdf 1759 kB)

  Swimming pools and other recreational water environments:
  Guidelines for safe recreational water environments - Volume 2: Swimming pools and similar environments (WHO, pdf 1236 kB)
   

• Water systems of buildings, cold household water and domestic hot water

  Action threshold 1 000 cfu/l.

  Measures must be taken to prevent Legionella if the Legionella concentration in the water sample taken from the water system of the building is 1000 cfu/l or higher.

  Under the Decree of the Ministry of Social Affairs and Health on the Quality and Monitoring of Household Water and the Risk Management of Water Systems of Buildings (1352/2015), which entered into effect on 12 January 2023, the action threshold for legionella concentrations in household water and hot domestic water is 1000 cfu/l.
  Decree of the Ministry of Social Affairs and Health on the Quality and Monitoring of Household Water and the Risk Management of Water Systems of Buildings (1352/2015) (Finlex, in Finnish)

  Instructions for Legionella control measures can be found in Valvira's guideline:  
  Risk assessment of Legionella bacteria and lead in the water systems of buildings and risk management (National Supervisory Authority for Welfare and Health Valvira, pdf 371 kB, in Finnish)

  In addition, ESGLI Guidelines contain instructions on cold household water and domestic hot water and staggered concentration limits, according to which Legionella control measures should be taken:
  ESGLI European Technical Guidelines for the Prevention Control and Investigation of Infections Caused by Legionella species June 2017 (ESCMID, pdf 1840 kB).
   

• Cooling water (cooling tower system)

  Recommended action thresholds and control measures for cooling waters:

  • ≤ 1000 cfu/l: no need for measures.
  • > 1000 cfu/l, recommended action threshold: re-sample, reviewing and enhancing control measures.
  • > 10 000 cfu/l, recommended rapid action threshold: switching off the tower, re-sample, biocide treatment, review of control measures.

  The reference concentrations are based on the ESGLI guidelines (Table 4):
  ESGLI European Technical Guidelines for the Prevention Control and Investigation of Infections Caused by Legionella species June 2017 (ESCMID, pdf 1840 kB)
   

• Pool water

  Legionellae must not be present in pool water of a good quality.

  No need for measures: not observed (entry < 10 cfu/l).

  The reference concentration is based on the Application directives for the Pool Water Decree (page 24):
  Application directives for the Pool Water Decree (National Supervisory Authority for Welfare and Health Valvira, pdf  2.1 MB) (in Finnish)
   

• Spa pool water

  Recommended action thresholds and control measures for spa pool waters:

  • Not detected: no need for measures.
  • Detected or < 1000 cfu/l, recommended action threshold: re-sample, cleaning measures, i.e. draining and refilling, review of control measures, and control samples on the following day and in 1–4 weeks’ time.
  • ≥ 1000 cfu/l, recommended rapid action threshold: immediate closure of the spa pool and isolation of the area, shock chlorination with concentration of 50 mg/l for one hour by circulating water in the system, draining the pool and repeated chlorination of pool water and control samples. The pool shall be kept closed until all remedial measures have been taken, legionellae have no longer been detected in the samples and the risk assessment is satisfactory. 

  The reference concentrations are based on the ESGLI guidelines (Table 7):
  ESGLI European Technical Guidelines for the Prevention Control and Investigation of Infections Caused by Legionella species June 2017 (ESCMID, pdf 1840 kB)
   

• Humidifier water and spray water

  Recommended action thresholds and control measures for humidifier water and spray water:

  • Not detected: no need for measures.
  • Detected, recommended action threshold: should be kept clean, regular disinfection and samples, risk assessment.

  The reference concentrations are based on the ESGLI guidelines (page 101):
  ESGLI European Technical Guidelines for the Prevention Control and Investigation of Infections Caused by Legionella species June 2017 (ESCMID, pdf 1840 kB)

• Dental water systems

  No need for measures: < 100 cfu/l (target concentration).

  The reference concentration is based on ESGLI’s guidelines for dental water systems (page 4):
  ESGLI Guidance for managing Legionella in dental water systems during the COVID-19 pandemic (ESCMID, pdf 202 kB)
   

• Cold household water on ships

  No need for measures: < 1000 cfu/l (target concentration, in the format <100 cfu/100 ml in the table).

  The reference concentration is based on WHO’s guidelines (Table 2-2):
  Guide to ship sanitation (Table 2-2) (WHO, pdf 3 MB)

• Domestic hot water on ships

  No need for measures: < 1000 cfu/l (target concentration, in the format <100 cfu/100 ml in the table).

  The reference concentration is based on WHO’s guidelines (Table 2-2):
  Guide to ship sanitation (Table 2-2) (WHO, pdf 3 MB)

• Water in spa pools on ships

  No need for measures: not detected (concentration < 1 cfu/100 ml recommended in the text).

  The reference concentration is based on WHO’s guidelines (page 109):
  Guide to ship sanitation (Table 2-2) (WHO, pdf 3 MB)