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Managing hot water systems in building plumbing systems during the Covid-19 Pandemic

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What is a hot water system? And why is it important?

Hot water systems enable hot water to be distributed to different units of a building and can be implemented either in a one-pipe or two-pipe system. Most plumbing systems in modern buildings use a two-pipe system which facilitates the re-circulation of the hot water and minimizes water wastage as compared to the one-pipe system.

Hot water circulating systems are important as they provide water at a comfortable temperature for users by mixing hot and cold water. These systems also maintain the safety levels of the hot water by preventing the growth of legionella infections, a commonly known waterborne infection in plumbing systems.

What causes legionella infection?

Legionella bacteria can be found in various engineered systems that promote the growth of biofilm which include drinking water supplies, building plumbing systems, and points of usage such as faucets and showerheads. These water systems are often identified with humidity, stagnant water, and the scarcity of chemical disinfectants, which are conditions that boost the growth rate of Legionella. From these “polluted” water systems, one can be put at risk of contracting Legionella infection when they breathe in contaminated aerosol; liquid droplets in the air.

How to prevent the growth of legionella infections?

One of the key factors to prevent the growth of legionella bacteria is temperature. Many hot water systems regulations highlight temperature control measures such as:

• The temperature of the water leaving the heater in recirculating hot water systems should not be below 60°C, and the temperature of the water that returns should not be below 50°C.

• The temperature of hot water at the tap should reach its maximum value within one minute and not be lower than 50°C, except where thermostatic mixing valves are installed.

Ensuring safe and reliable hot water systems in building plumbing systems during the Covid-19 Pandemic

Since the pandemic, many cities and buildings have entered the lock down stage. As a result, there is usually low water consumption in hot water systems of closed or partially used buildings. In such cases, water will remain unused and stagnant in the systems for a longer period. This can potentially lead to a gradual drop in hot water temperature to unsafe levels, increasing the risk of contracting legionella infection once the lockdown ends. Additionally, co-infection of Legionella and Covid-19 could occur which increases the risk of fatality. Therefore, Legionella preventive measures must be taken to ensure safe water systems.

Introducing effective thermal balancing and disinfection solutions for hot water systems

The risk of legionella in hot water systems can be reduced by introducing fixed orifice balancing valves and thermostatic regulating valves. These user-friendly valves not only enable users to easily set the water temperature to safe levels but also enhance user comfort levels by minimizing any delays for mixed water. For instance, users can set water temperatures to 55°C as it is the optimal temperature for inhibiting the growth of Legionella Bacteria. The valves also provide safe and constant water temperature throughout the system by establishing appropriate hydronic balancing.

Thermal disinfection solutions for hot water systems can be further enhanced using an electronically controlled mixing valve. Through an electronic regulator, it prevents legionella growth through a series of automatic programs to facilitate thermal disinfection of the system and maintain the temperature of hot water in the system despite pressure and temperature variations of cold and hot water.

The mixing valve also allows smart monitoring, which helps in enhancing hot water system reliability, minimizing operational cost, and facilitating data acquisition for further data analysis that can be beneficial to the building management team.

For more information on the thermal balancing valves and electronic mixing valves, please contact us through our email: or call us at 67422770.


1) The National Academies of Sciences Engineering Medicine -

2) World Health Organization -

3) Centers for Disease Control and Prevention -

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