All facilities that use water in their processes must pay special attention to the prevention and control of one of the most important bacterial diseases of environmental origin: legionellosis.
This is so much so that there are specific regulations on water quality (such as Royal Decree 487/2022 and RD 3/2023 in Spain), which establish the health requirements for the prevention and control of legionellosis, among others.
What is Legionella?
Legionella is an environmental bacterium that causes legionellosis, a lung infection characterised by pneumonia with high fever in most cases.
This disease is associated with equipment and systems that use water at temperatures that favour the proliferation of the bacteria and that in many cases produce aerosols during operation, generally spreading the infection in a communal and nosocomial manner.
Legionella can survive in a wide range of physico-chemical conditions, multiplying at temperatures between 20ºC and 50ºC, and are naturally found in natural reservoirs such as surface water, i.e. lakes, rivers, ponds and even seawater.
From these reservoirs, the bacteria are able to colonise supply systems and distribution networks, making specific control systems essential.
Which installations are most susceptible to a Legionella outbreak?
Facilities most likely to support Legionella proliferation include cold water distribution systems for human consumption and domestic hot water systems, cooling towers, sprinkler irrigation systems, industrial humidification systems, evaporative condensers, spas or swimming pools with agitation and recirculation systems, among others.
If these installations are poorly designed, badly installed or not properly maintained, they favour water stagnation and the accumulation of water nutrients such as sludge, organic matter, corrosion materials and amoebae, forming a bio-layer, which together with a favourable temperature, allows the multiplication of Legionella up to concentrations that are infectious for humans.
Control of physico-chemical parameters in installations
The control of physico-chemical parameters that influence the growth and proliferation of Legionella in susceptible installations is essential to prevent and manage the risk of outbreaks.
According to RD 3/2023, the water quality parameters to be monitored are:
- Water temperature: as the bacteria multiply best between 20 and 50ºC, with optimal growth between 35 and 37ºC, it is necessary to keep the water either below 20ºC or above 50ºC to minimise the risk of multiplication.
- Water pH: Bacteria can survive in a wide range of pHs, but their proliferation is more efficient at neutral or slightly alkaline pHs, so it is necessary to control and maintain the pH of the water within ranges that do not favour bacterial growth, generally between 7.0 and 7.8.
- Free residual chlorine and other biocides: the disinfection of drinking water with free chlorine or in combination with other biocides such as chlorine dioxide is essential to inhibit the growth of Legionella, so controlling the levels of free residual chlorine is essential to ensure proper disinfection.
- Turbidity: Water hardness due to the presence of calcium and magnesium can contribute to the formation of scale that protects Legionella, so it is necessary to control turbidity levels to prevent scale formation.
- Conductivity: Conductivity measures the amount of dissolved ions in water and can indicate the presence of contaminants and the effectiveness of water treatments, so monitoring it can detect changes that may require treatment adjustments.
Legionella Control and Prevention Systems: Drinking Water Test Panels
With over 40 years of experience in the industry, Envira is an expert in the continuous monitoring of air and water quality.
Our water quality measurement equipment allows us to provide specific solutions adapted to the specific needs of each industry, as is the case with our drinking water quality measurement panel.
This panel provides a complete solution for reliable and accurate control of physico-chemical parameters in the treatment and distribution of legionella-free drinking water.
It includes pH, conductivity, turbidity and free chlorine sensors and a data transmitter to ensure correct measurements at each stage of water treatment involving disinfection, such as pretreatment, conditioning, disinfection or distribution.
A solution that allows compliance with RD 3/2023 and RD 487/2022 in a simple and effective way.
