Legionella are bacteria that live in water. They naturally occur in low concentrations in almost all waterbodies.

Legionella occurs naturally in low concentrations in almost all bodies of water. Through the public water supply they enter technical water systems or drinking water systems, where there are often favorable conditions for a strong reproduction to dangerous concentrations (keywords water temperature 25°C-45°C, stagnation of the water, nutrients, biofilm, old lines).

Legionella can survive in cold water, but cannot multiply. Water temperatures between 25-45 °C represent optimal temperature conditions for legionella, where they can multiply rapidly. Heating the water temperature to more than 55 °C inhibits the growth of legionella and at more than 60 °C they are killed.

Legionella can cause infectious diseases (legionellosis) in humans: Legionnaires' disease or, in a milder form, Pontiac fever. Legionnaires' disease is a special form of pneumonia; other common symptoms include fever, cough, chills and headache. This disease is difficult to treat and is fatal in around 5-10% of known cases, although a high number of unreported cases are suspected to be unrecognized or unrecorded. Older people and people with weakened immune systems due to previous illnesses are particularly at risk. Legionellosis is a notifiable disease.

In Germany, around 1,860 cases of Legionnaires' disease were reported to the Robert Koch Institute (RKI) in 2021, and around 11,000 cases were recorded across Europe. The numbers are constantly increasing. In addition to better diagnosis and recording, the main reasons for this are the increasing number of technical water systems for cooling or air conditioning, as well as reduced system temperatures as a result of energy saving measures.

One becomes infected through droplet infection, i.e. by inhaling aerosols (atomized water droplets) that contain Legionella. In the lungs, the bacteria attack the lung cells, multiply and trigger the disease. However, if water contaminated with Legionella is swallowed, there is usually no risk of infection.

If technical water systems or drinking water systems are contaminated with Legionella, any type of water atomization, misting or evaporation can result in dangerous aerosols containing Legionella (smallest water droplets). The greatest source of danger are open cooling tower systems that atomize and evaporate water for cooling purposes. Aerosols released into the environment can cause mass illness. Aerosols are also created in the same way when showering (calcified shower heads are particularly unfavorable), in whirlpools, car washes or during dental treatments. Other known sources of aerosols containing Legionella include water-based industrial processes, wet separators for air purification, sprinkler systems (e.g. field or garden irrigation) or humidifiers (e.g. air humidifiers or vegetable humidifiers in supermarkets). The most exotic sources of Legionella infections known to us are evaporation from warm, moist potting soil or atomized windshield wiper fluid in vehicles.

The threat posed by Legionella to public health is assessed by the World Health Organization (WHO), among others, as high. There are numerous regulations and laws to prevent and detect contamination in technical water systems and drinking water systems. In Germany there are two main laws. For technical water systems, this is the 42nd regulation for the implementation of the Federal Immission Control Act (42nd BImSchV). For drinking water systems it is the Drinking Water Ordinance (TrinkwV). Both laws regulate operator responsibility, specify limit and action values, and define methods and frequency of microbiological controls. Accompanying this, there are numerous guidelines for the professional execution and intended operation of the systems in question.

Drinking water systems are water distribution networks or hot water preparation systems in all types of buildings. If drinking water is provided there for use by third parties as part of a public or commercial activity, the Drinking Water Ordinance (TrinkwV) applies. From the transfer point from the public water supplier to the building, the operator is generally responsible for the water quality. If the hot water heating system meets certain technical criteria, the TrinkwV requires regular tests for Legionella by approved testing centers using an approved procedure. This applies, among other things, to rented residential properties, hotels, hospitals or sports facilities, but not single and two-family homes. If Legionella contamination is found above a limit value, the health department must be informed and measures must be taken.

This affects technical water systems that release aerosols into the air or environment via evaporation or nebulization. These can be cooling towers, wet separators for air purification or evaporative cooling systems.

The 42nd Ordinance for the Implementation of the Federal Immission Control Act (42nd BImSchV) within the framework of the Federal Immission Control Act sets more extensive and stricter requirements for technical systems than the Drinking Water Ordinance for drinking water systems. Among other things Depending on the size of the cooling tower, microbiological examinations must be carried out monthly or every 3 months by approved bodies using an approved method, and in-house indicative examinations must be carried out every 14 days, for which suitable alternative methods may be used.

Humidifiers, sprinkler systems, tunnel pasteurizers, car wash systems or water-based industrial processes (e.g. paper production) are not covered by the German drinking water ordinance (TrinkwV) or the Federal Immission Control Act (42. BImSchV). However, there are laws and regulations that recommend regular checks, including the Wastewater Ordinance Annex 28, the Occupational Safety and Health Act or the Workplace Ordinance, if aerosols from the systems can be inhaled by employees.

In public swimming pools there are hot water preparation systems for the showers that fall under the Drinking Water Ordinance (TrinkwV) and must be operated and sampled accordingly. According to the Infection Protection Act (IfSG), the swimming and bathing pool water must not contain any microbiological contamination that is harmful to health, as water can be swallowed, misted and evaporated. DIN 19643, in turn, specifies limit values for Legionella, Pseudomonads, E. coli and the total number of germs, but leaves it open how often this should be checked. Most public pools carry out tests every 14 days and, due to strict limit values, have these carried out by approved bodies with approved procedures.

The operator of a system that is generally covered with regard to microbiological contamination by the Drinking Water Ordinance (TrinkwV), the Federal Immission Control Ordinance (42nd BImSchV) or the Infection Protection Act (IfSG) is responsible for the quality of the water and compliance with limit values. If he does not fulfill his operating obligations, for example if he does not carry out the prescribed legionella tests, this is an administrative offense according to the Infection Protection Act, for which a fine of up to €25,000 can be imposed. If people become ill due to intentional misconduct by the operator, prison sentences of up to 5 years are possible.

Through regular sampling followed by laboratory testing for Legionella. In Germany, only the procedure according to ISO 11731 is approved for legally compliant examinations. Sampling and testing may only be carried out by accredited and approved laboratories. It takes approximately 10-14 days from the sampling to the notification of the result. For voluntarily self-conducted (indicative) examinations, you can also use suitable alternative procedures or rapid test kits. These often deliver faster, but usually less accurate and only qualitative results.

If the so-called measure value is exceeded (according to the Drinking Water Ordinance 100 Legionella colonies/100ml), this must be reported to the responsible health authority. The laboratory usually does this directly. It is then advisable to involve an experienced service provider for immediate and renovation measures. Possible measures range from flushing the system, to thermal and chemical disinfection, to replacing system parts. This is accompanied by further close Legionella investigations in order to evaluate the effectiveness of the measures. During the renovation work, use of the facility is restricted or interrupted. Often a risk assessment must be carried out by an expert in order to be able to better assess the risks in the system.

For rental properties, but especially for hotels, pools or hospitals, legionella infestation and possible plant shutdowns are unpleasant because they disrupt operations. If there is public reporting, there is also a risk of a loss of reputation. Costs and effort for evicted tenants, rent reductions, containment measures (e.g. legionella filters), renovation measures, close follow-up investigations, business closures or reports can be considerable. It is worthwhile to operate your systems conscientiously and to carry out regular examinations for prevention purposes.

The newly developed and patent-pending BlueLab analysis process is based on an antigen-antibody reaction combined with an optical analysis. A water sample taken is labeled and then analyzed directly. The procedure and the associated device are independent and not comparable to common laboratory procedures (e.g. PCR or flow cytometry) or known test kits. The goals of the process development were on-site analysis, automatability, as well as fast and quantitative results with high sensitivity and specificity with regard to Legionella spp. The BlueLab process is probably the most technologically advanced analysis method currently available.

The BlueLab process and the different device variants are aimed at all conceivable applications for Legionella testings. Due to various legal requirements, these are: Cooling towers, evaporative cooling systems and wet separators Thermae & Pool companies Hospitals & Care facilities Hotels Public buildings that have aerosol generating devices (e.g. showers) Sports facilities Rented properties Our solutions are also aimed at owners or landlords of one- and two-family houses, or commercial businesses whose drinking water systems do not fall under the Drinking Water Ordinance, but who still want to examine their water systems as a preventive measure.

User-friendly: automated and on-site detection of legionella and other bacteria Precise: selectivity and sensitivity validated in application environments Fast: quantitative results are available within 1-2 hours after sampling or starting the analysis in the benchtop device Economical: low consumable costs per examination In the case of permanently installed devices, continuously: additional sensors permanently monitor risk parameters of the system