Illes Control - control de plagas en Mallorca

Control of Legionella bacteria

Illes Control

Cleaning and disinfection, consulting and revision for Legionella bacteria.

The problem

Control legionela mallorca

The legionella is a bacteria that grows and multiplies in water. Therefor, every watersystem in a building, including potable water supply, can be a risk factor and can be infected in any place.

An legionella infection can cause Pontiac-fever, a flu-like condition, or even legionellosis, a severe pneumonia that can be deadly.

In order to prevent infections, a treatment for disinfection and increase of water quality is necessary..

Poorly designed water systems that are not maintained or not well maintained, as well as stagnant water, can favour the growth and colonization of legionella bacteria. Sludge, organic material, corrosive material and amoeba form a biofilm that can increase the risk of an infection. In combination with a temperature that favours the bacteria growth, concentrations rise to a level that is pathogenic for humans. Installations that release or spray water into the air can affect the respiratory system, as small droplets in the air that carry the bacteria can cause an infection.

Our solution

Audit and counseling prevention of legionella

Illes Control delivers a broad section of services, under the royal decree 865/2003, including documentation, consulting, cleaning and disinfection.

CONSULTING: We offer consulting services prior to inspections by public health authorities, advise in case of deviation or deficiencies in installations, and we inform you of potential methods that should be applied.


  • we create a control register.
  • we create and check the control register regularly, to ensure the compliance with the requirements and document and inform about any deviations.
  • Comprehensive management: in the control register all defined and conducted measures are documented and revised.
  • we establish a program to prevent and control the legionella bacteria: the service includes the analysis of the situation, a program for water treatment, final analysis and a risk analysis of the installation.

Cleaning and disinfection:

Watersystems for hot and potable water are cleaned and disinfected at least once a year, before commissioning, after the system is shut down for more than a month, after repair or modification of the structur, before general inspections or if public health authorities demands it.

Hot water systems: thermal disinfection
cleaning and disinfection against legionella

  • The system is emptied, and, if necessary, the walls of the water deposits are cleaned thoroughly and carefully rinsed with clear, clean water, after the necessary repairs are done.
  • The water reservoir is filled and water is heated to 70 degrees for two hours. Subsequently, section by section is opened for about 5 minutes. It is ensured that all terminal units of the system reach a temperature of 60 degrees.
  • The water reservoir is emptied and filled again for regular use.

Cold potable water: chemical disinfection

Elements that can be dismantled, like faucets and showers, are cleaned thoroughly with appropiate products that eliminate incrustations and residues by submerging them for 30 minutes in a chloric solution (20mg/l) and then rinsing them with cold, clear water.

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The critical points in the cold water system are as follows:
  • The cisterns and auxiliary water tanks. In these cases, the proliferation of the bacteria occurs in systems with a poor state of maintenance and cleaning and/or subject to direct sunlight, since the bacteria are found with temperature and nutrients that favor their growth. The stagnation of water in the tank and inadequate closures, which allow external dirt to enter, are factors that favour the settlement and proliferation of bacteria.
  • Blind and infrequently used branches. The stagnation of water facilitates the formation of biofilms in which bacteria can hide and find nutrients to multiply. Blind branches are frequent in old or remodeled buildings. The existence of low-use end-of-life taps and rooms unoccupied for a certain time can also be a problem, as they allow water to stagnate.  Therefore, bleedings must be carried out periodically.
  • Drinking water network connections to non-drinking water systems are another point of risk. Connections to the fire fighting system or to the irrigation system that lack non-return valves.
  • The pressure groups, which can be arranged for serial entry, so that one is almost never in operation causing water stagnation. In addition, they sometimes lack a bottom outlet for bleeding or are difficult to clean.
The critical points in the domestic hot water system are as follows:
  • Production is centralized. The flow of hot water has many variations throughout the day depending on the season, type of installation, time of day, etc. All this requires hot water accumulators to guarantee the supply of hot water on demand. Therefore, it is important to control the temperature in the accumulators, because if at any time it is lower than 45ºC, the proliferation of Legionella will be favoured.
  • The heat exchangers. Their main risk is that at high temperatures the deposition of salts is favoured which could produce porosities in the plate and the consequent mixing of the water in the circuit with the domestic hot water. Therefore, a good maintenance is recommended, which will be favoured if the exchangers are external. It is also recommended that a pump be installed to allow the water to be recirculated within the tank itself.
  • Thermal stratification. The variation of temperature in the accumulator can favour the microbial growth if the bacteria are found at adequate temperatures. Therefore, it is necessary to control it and to avoid thermal stratification it is recommended that the accumulators are vertical and connected in series.
  • The terminal points. The cleaning and disinfection of the terminal points (taps, showers) is a preventive practice that will reduce the amount of nutrients and, therefore, hinder bacterial growth.