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Legionella and bacteria

Drinking water in Germany actually contains no bacteria. The water supply utility company which, at least in Germany, also strictly monitors and constantly checks the water, ensures this. The value given from the authorities are less then 100 CFU/mL . There are press reports of bacterial contamination of the water only if malfunctions or problems occur. Bacteria (e.g. legionella) may occur in hot water storage tanks which, nowadays, are frequently operated at low temperatures for reasons relating to energy saving.

Once in the system, these bacteria can be fought only with difficulty. Legionella frequently also infest the encrustations in the pipes which then provide a certain degree of protection, e.g. during high-temperature rehabilitation.

Legionella are generally fought by thermal treatment, UV radiation or the addition of chemicals. In the case of thermal treatment, the water is either maintained constantly at a high temperature so that the legionella die off or the hot-water system is heated at certain intervals in order to kill off the bacteria. Both procedures are very complex and expensive. Thus, it must be ensured that no water is used during rehabilitation since, otherwise, this could result in the risk of burns. In the case of UV light treatment, the bacteria flowing through this light are reliably killed off. However, the difficulty is ensuring that all water circulates in the system. Complex water systems frequently feature so-called dead legs1 in which water stands for a very long time. Bacteria are able to grow at such points forming biofilm and are then entrained into the system.

Using units developed specifically for this purpose, Pursanova TM has, achieved very good results with legionella and other bacteria. This means that the legionella have reduced in number over a period of several weeks and ultimately disappeared entirely.

Important: In such cases, it is essential, in all circumstances, to agree on a demonstration phase during which the water must always be tested by an independent laboratory for a long period in order to check whether the bacterial count in the water has dropped before a statement can be made on the effectiveness. Two properties of the Pursanova TM units are important in this case. Firstly, active oscillations are emitted and these influence the bacteria directly. Secondly, the reduction of encrustations in the pipes destroys the habitat of the bacteria. The fact that Pursanova TM even works in standing water and that the oscillations are propagated in the water is a very major advantage in this case since even so-called dead legs1 are reached by the oscillations and, thus, the bacteria are also influenced at these points.
Important: At this point, we must expressly point out that these results can be achieved only with special-purpose Pursanova TM units featuring specific oscillations. A standard unit will be unable to achieve such results.

Important: We must point out that Pursanova TM is not capable of directly killing any germs in the water and thus restoring drinking water quality. Filters or similar, appropriate measures must be used in order to achieve such a situation.


See also the Case Study Legionella in Retirment Homes or bacteria in cooling tower.

1 The term "dead legs" means parts of a pipe through which the medium does not flow, e.g. a stub line leading to a valve which is opened rarely or never.