Jian Fan - stock.adobe.comthe essentials in brief
- Legionella bacteria multiply particularly in summer when cold water pipes warm up and water remains in the pipes for extended periods of time.
- Consistent temperature control and regular use of the drinking water installation help to reduce the risk of Legionella.
- In many rented apartment buildings, legionella testing is legally required and must usually be carried out every three years.
- If the technical action level of 100 CFU Legionella per 100 milliliters of water is reached or exceeded, operators must investigate the causes and, if necessary, initiate further measures.
- Landlords and property managers are responsible for ensuring that legionella testing is carried out on time and can, under certain conditions, pass the costs on to the operating costs.
Legionella: Why the warm season is particularly critical
Legionella bacteria can form in drinking water systems, especially at unfavorable temperatures and when water remains stagnant in pipes for extended periods. Minol explains what landlords and property managers of apartment buildings need to know about the legally required Legionella testing.
The risk of Legionella bacteria in drinking water increases particularly in summer, as higher outside temperatures can cause cold water pipes to heat up uncomfortably. If the water is also left standing for extended periods, ideal conditions for Legionella bacteria to multiply are created.
Areas of the drinking water installation with low water flow are particularly affected. During vacation periods or when apartments are vacant, individual taps are often not used for days or even weeks. The resulting stagnation promotes the spread of Legionella bacteria in the drinking water system.
Regular testing for Legionella and adherence to prescribed temperatures are therefore important measures for protecting health. If Legionella bacteria enter the lungs via finely atomized water, for example while showering, they can cause Legionnaires' disease. This is a severe form of pneumonia that can particularly affect older people and those with weakened immune systems.
Preventing Legionella: Regular use and correct temperatures
Operators can significantly reduce the risk by ensuring regular water exchange and proper temperature control. It is helpful to advise tenants that after a prolonged absence, taps should be flushed until fresh water at a constant temperature flows.
If apartments or parts of buildings are vacant, landlords or property managers should have the rarely used taps flushed regularly. This ensures water exchange in the pipes and prevents stagnation.
Equally important is compliance with the technical requirements for water temperature:
- Drinking water should reach at least 60 °C at the outlet of the water heater.
- A minimum temperature of 55 °C should be maintained in the hot water system.
- Cold water should ideally remain below 20 °C for extended periods.
These temperatures comply with generally accepted engineering standards and help to effectively limit the proliferation of Legionella bacteria.
Legionella testing according to the Drinking Water Ordinance: What obligations apply?
The obligation to test for Legionella arises from the Drinking Water Ordinance, which implements the requirements of the European Drinking Water Directive. For installations subject to testing, the examination must generally be carried out at least every three years.
Since the revised Drinking Water Ordinance came into effect in 2023, operators must take action as soon as the technical action level of 100 colony-forming units (CFU) of Legionella bacteria per 100 milliliters of water is reached. If this level is reached or exceeded, the causes must be investigated and, if necessary, further measures must be initiated. These may include, for example, further investigations and a risk assessment in coordination with the responsible public health department. The aim is to identify potential hygiene risks early on and to maintain the drinking water installation in a proper and hygienically sound condition at all times.
When is a Legionella test mandatory in an apartment building?
Legionella testing is legally required in rented apartment buildings with central hot water systems under certain conditions. The responsibility for ensuring timely testing lies with the operators of the drinking water system, usually landlords or property managers. Sampling and testing may only be carried out by approved or accredited testing laboratories.
Easily organize Legionella testing for landlords and property managers
Organizing a Legionella test involves several steps, from scheduling and sampling to documenting the results. Therefore, it is advisable for landlords and property managers to use experienced service providers.
Suzi Media – stock.adobe.comB.One Legionella Test
Minol has been supporting the housing industry in conducting Legionella testing since 2012. Their experts are familiar with the requirements of the Drinking Water Ordinance and handle the entire process: from scheduling appointments and sampling in cooperation with accredited laboratories to documenting the results in the customer portal.
Author
Susanne Frey | Produktmanagerin Minol Messtechnik W. Lehmann GmbH & Co. KG
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