Operators of drinking water systems such as property landlords, hotels, hospitals, nursing homes, public buildings, and more have been obligated since 2011 to regularly test their drinking water systems for Legionella contamination. This obligation applies within the EU - in Germany, it is prescribed in the Drinking Water Ordinance (TrinkwV). 

And that's a good thing because annually in Germany, 15,000 to 30,000 people fall ill with Legionnaires' disease and/or Pontiac fever caused by Legionella. Even 10 to 15% of those affected die from it.

Currently, proof of Legionella contamination in drinking water according to the Drinking Water Ordinance (TrinkwV) can only be provided through the method approved by the Federal Environment Agency, which is the incubation method. In this method, water samples are incubated in a breeding cabinet for 8 to 10 days.

And here comes the new digital Legionella test by SuSAn-Water GmbH, which is based on an analysis method from medical technology, providing a functional system for drinking water analysis.

Compared to the well-known incubation method, SuSAn's new digital Legionella test reduces individual steps and dramatically shortens the total time to results. Current practical tests show comparable quality, and submission for certification to the Federal Environment Agency (UBA) is underway.

It is an antibody-based method that delivers analysis results within just a few minutes. To utilize this technology, SuSAn-Water GmbH has modified the sample collection process and developed its own filtering system.

The test operates based on test strips containing corresponding antibodies, which are processed in a multi-patented analysis machine.

The SuSAn system detects approximately 99% of all Legionella contaminations with a detection limit of at least 100 CFU/100 ml.

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(Foto: Analysis machine)

The multi-patented analysis machine originates from medical technology. It is capable of evaluating test strips based on the ELISA detection principle and providing analysis results within just a few minutes. Before the analysis, the test strips are dripped with the water sample taken and the Legionella antibodies developed by SuSAn-Water GmbH.

To utilize this technology, SuSAn-Water GmbH has modified the sampling procedure and additionally developed its own filtering system, which is being patented.

The analysis machine comes with software installed on a computer, which controls the machine and processes the results of the examination.

The challenge with this analysis method is to concentrate the Legionella count in the water sample while simultaneously reducing the amount of water so that the analysis produces a valid result. Understandably, only minimal amounts of sample material can be processed on the test strip - a water droplet. Therefore, three liters of tap water are filtered to yield this water droplet, ensuring it contains exactly the same Legionella concentration as the entire three-liter sample.

For this purpose, SuSAn-Water GmbH has developed a filter box that utilizes capillary action to quickly and effectively pass the required amount of water through a filter, which captures any germ sediment. By adding a stabilizing solution, this sediment is dissolved from the filter.

 (Foto: Filterbox Prototyp)

1. Sample collection

As usual, the water sampling point is prepared to be germ-free by flaming. Subsequently, one liter of water is drained, as is also done in the incubation method.

Then, three liters of water are passed through the pre-prepared SuSAn filter box using the provided hoses. Any remaining water is then drained, and the filter box is filled with the provided stabilizer solution.

2. Transport

If the analysis is not to be carried out on-site immediately, SuSAn-Water GmbH offers a special transport case for convenient and secure transportation of the filter boxes. Unlike the water containers used in the Legionella test with the incubation method, the filter boxes of the digital SuSAn Legionella test do not need to be cooled.

3. Analyse

The sample is taken from the filter box, and antibodies are added to it. A drop of the liquid is applied to the test strip and inserted into the analysis machine.

4. Result

After a few minutes, the result of the examination is available and transferred to the connected computer.

The analysis results are transferred into the evaluation software on the computer and provided in this format as a document.