Legionella treatment

Legionella treatmentLegionella treatment

Where is UV treatment against legionella recommended?

The legionellosis is a serious infection of the lungs. It is caused by a Legionella type bacteria. In 15% of cases, it leads to death. The germ responsible for the disease is Legionella. It is a type of bacillus that lives in fresh water and moist soil.
Legionellosis is contracted through airborne transmission and inhalation of contaminated water as an aerosol and microdroplets, for example, via steam from the shower. The legionella bacteria multiplies in warm waters and its optimum temperature for reproduction is between 25 and 45°C, with an optimum at 35°C. Legionella is able to survive several months in fresh water and more than a year in a tap at room temperature. Iron, zinc, potassium and certain rubber constituents used in plumbing also stimulate their growth. Its reduction is therefore an environmental and public health issue.

This bacteria proliferates in water installations.

The main sources of exposure to Legionella for humans are domestic hot water systems (DHW) and the wet cooling towers (WCT). This bacteria can also colonise other installations which must be treated and monitored regularly.

  • Whirlpool installations or hot tubs used for relaxation, spas, balneotherapy and hydrotherapy,
  • Medical equipment for aerosol respiratory treatments,
  • Air conditioning circuits,
  • Poorly insulated cold water circuits,
  • Air humidifiers and misters,
  • Collective water misting systems,
  • Decorative fountains


To ensure the health and safety of users, Legionella monitoring is regulated by law. For residential buildings, hotels, tourist accommodations, campsites, hospitals, the regulatory test in accordance with NFT90-431 (detection and enumeration of Legionella) on all points at risk of a domestic hot water network must be carried out once a year. Industrial sites (food, agri-food, pharmaceuticals, cosmetics, etc.) are, for their part, required to carry out legionella analysis monthly or quarterly.

Preventing the risk of legionellosis using UV treatment

With our long-standing experience in UV treatment for pool water and wastewater, we were able to develop a range of effective devices against legionella. We offer a compact range intended for low flow rates up to 6 m3/h and an industrial range for higher flow rates on cooling towers for example. Easy to install, UV units allow your customers to act immediately on their legionella alerts during their annual, quarterly or monthly analyses. With its physical disinfection process, the UV reactor will destroy living microorganisms. UVc treatment creates a highly effective “antibacterial” barrier in addition to the scale prevention, bactericide and biodispersant treatment. UVs create an abnormal bond on the DNA of Legionella which immediately loses its ability to reproduce. Cell division is no longer possible which in turn, stops bacterial proliferation. Depending on the type of network requiring treatment, the UV units are positioned on the outlet of the domestic hot water production system (DHW circuits), on the recycling loop (wet cooling tower, air conditioning, balneotherapy and fountains) or at the outlet of the pumps (humidifier and mister). Before installing and starting the UV unit, the pipework must be given a shock treatment either with a thermal or chlorine disinfection. Analysing the entire water network is also required to remove the risk of bacteria developing in the dead legs of the pipework. To fully reduce all legionella strains and all human pathogenic bacteria, a UV dose ranging from 40 mJ/cm² to 60 mJ/cm² can be applied.


Pros of UVGERMI LEGIONELLA range - Made in France

  • Biocide reduction,
  • Low energy consumption,
  • Very simple installation,
  • Reduced maintenance cost for UV lamp replacement and quartz sleeve cleaning,
  • Options for the industrial range: automatic or manual cleaning, remote control and alarms, vertical installation with air purge.

Find out more Our full LEGIONELLA range
Legionella treatment
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