Legionella and how to defend against it

Where does Legionella come from?

Legionella bacteria are commonly found in both water and soil. Infection usually occurs by inhalation of aerosol contaminated with this bacterium. Traditionally, it is spread by ventilation, air conditioning, water supply systems supplying hot and cold water, hot tubs, garden sprinklers, but also by a water nozzle – i.e. devices that create aerosol during their operation. However, they also occur in natural pools, recreational pools, etc. Human to human transmission, such as sneezing or coughing, has not yet been recorded.
From the point of view of water systems, Legionella can occur in any type of drinking water, where it can survive temperatures below 20 °C, but is not able to multiply. Proliferation takes place within the water temperature range of 20 to 50 °C and at pH 5,0 to 8,5, the optimal conditions for multiplication being considered to be the water temperature between 35 and 45 °C. Current research, however, shows that the temperature optimum is rather 25–50 °C and Legionella do not grow above 65 °C. Operators of hot water systems up to 60 °C or without good regulation (with variations at terminals up to 20 °C) can cultivate high temperature resistant Legionella in their systems.

Legionella in cold water systems

When designing cold water systems, water temperature, retention time, pipe material and, of course, regular maintenance are very important. Legionella itself, for example, creates a biofilm in pipes and tanks that protects them (even from disinfection) and also serves to attach them to the surface. Biofilm clogs pipes, reduces heat transfer efficiency, accelerates corrosion, etc.

How to prevent Legionella?

The basis for a successful fight against Legionella is prevention, i.e. a properly designed water supply system and ensuring:

• pipes for more resistant biofilm formation and overheating (thermal disinfection)
• water changes in a section shorter than the Legionella reproduction period (4 hours)
• possibility of disinfection, sampling
• minimizing operation at temperatures optimal for Legionella multiplication (20-45/50°C)
• effluents against back suction
• elimination of blind and unused water sections, especially for indirect water heating systems

The water pipeline operator should carry out a complete inspection once a year, but if Legionella still occurs, disinfection must be carried out.

Prevention of water stagnation with GWS products

The occurrence of Legionella and the multiplication of other micro-organisms in general are favorable periods with low or zero water consumption, when the water in the reservoir stands.  According to the World Health Organization (WHO), preventing the formation of sediments, sludge, slime and thus water stagnation is an important part of the Legionella prevention.
This can be prevented in any water system, regardless of its size, for example by using a composite pressure vessel or Global Water Solutions (GWS) in line adapter with FlowThru™ technology. GWS is at the forefront of innovation and new technologies for pressure vessels and is the most comprehensive supplier of pressure vessels in the world. Pumpa,a.s. is their exclusive distributor in the Czech Republic and Slovakia, and its range includes pressure vessels with FlowThru™ technology, which are ideally suited for constant pressure systems such as cold water booster stations controlled by frequency converters. They can be used mainly incommercial and residential buildings, hospitals, schools and the like.

 

FlowThru

FlowThru ™ containers have a built-in device that pushes water from the main supply line into the water chamber of the pressure vessel. This flow-through design ensures that the water always stays fresh, eliminates the risk of standing water and reduces the risk of bacteria in the water, such as Legionella. Continuous flushing ensures still fresh water in the tank, which helps responsible persons and entities to comply with operational regulations to ensure health, safety and related water management regulations.
Flow Thru™ Pressure Vessels are tested at different levels of manufacture to ensure the high quality and reliability of each individual vessel and are among the highest quality pressure vessels available today.