Legionella Control in Circuits
A set of cleaning, disinfection and monitoring measures that prevent Legionella bacteria from proliferating in water installations that generate aerosols.
Legionella is a genus of bacteria that lives naturally in water; the most relevant species for public health is Legionella pneumophila. It multiplies in warm water, between about 20 and 45 ºC, especially where water stagnates and there is sediment, scale or biofilm. It is transmitted by breathing in aerosols of contaminated water, not from person to person, and causes legionellosis: Legionnaires' disease, a form of pneumonia, or Pontiac fever, a mild flu-like form.
In Spain, Spanish Royal Decree 487/2022, amended by Spanish Royal Decree 614/2024, requires owners of risk installations (hot and cold water for human consumption, cooling towers and evaporative condensers, humidifiers, spas, ornamental fountains and vehicle wash tunnels, among others) to have a Legionella Prevention and Control Plan or a Legionella Health Plan based on a risk assessment. For cooling towers it sets cleaning and disinfection at least twice a year and monthly Legionella sampling; for domestic hot water, the storage tank at 60 ºC or higher and the return and taps at 50 ºC or higher. Only authorised or registered biocides may be used, and companies that treat third-party installations must be registered in the ROESB (Spanish Official Register of Biocide Establishments and Services). Because soil and limescale protect the bacteria, the programme combines removal of scale and biofilm with disinfection.
Instaquim products for cooling towers and circuits, according to their technical data sheets:
- Bacter 200 (pH 7 ± 1; registration no. 21-100-04598; UNE-EN 13623, 60 min at 30 ºC): biocide for legionella treatment in cooling towers and evaporative condensers, to be applied by specialised professional staff. Start of treatment: 0.2–0.4 % every 7 days; maintenance: 0.1–0.2 % weekly.
- Detercal (pH 2.0 ± 0.5 at 1 %): acid detergent for limescale deposits in towers, condensers and circuits, at 10–20 % at 40–60 ºC; rinse with water until neutral pH.