INDUSTRY NEWS
STUDY SHEDS LIGHT ON MICROBIOMES IN DHW INSTALLATIONS
A
new seminal study led by microbiologist Prof. emerit. Thomas Egli has brought to light the unexpected microbial communities thriving
within domestic hot water boilers. Discovering that hot water boilers are home to unique thermophilic bacterial communities (distinctly diff erent from those in the supplied cold drinking water), Professor Egli recommends maintaining boiler temperatures at between 50° and 60 °C (as recommended in most countries) to reduce the risk of growth of opportunistic pathogens. Professor Egli and his research team also found
that all hot-water samples were dominated by a handful of thermophilic bacterial strains belonging to the families Thermaceae, Hydrogenophilaceae, and Nitrosomodaceae. These strains are well- adapted to temperatures around 50-60° C, where most other bacteria cannot survive. These heat-loving microbes fl ourish in boilers’ warm environments, with total cell counts in hot-water two to three times higher than in cold-water. The study suggests that domestic hot water
boilers function as semi-continuous bioreactors, creating ideal conditions for thermophilic bacteria to grow. The heating process most likely transforms dissolved organic matter in cold water into usable organic carbon, fueling microbial growth. Boilers with UVC-treated cold water also supported active microbial communities, showing
that these bioreactors operate independently of the supplied cold drinking water.
The study also underlined that little attention has been given to the microbiology of domestic hot water installations, except for aspects of pathogenic legionella. Worldwide, regulations consider hot (or warm) water to be ‘heated drinking water’ that must comply with (cold) drinking water standards. Although no major pathogens have been associated specifi cally with hot water usage, these thermophilic strains may infl uence water quality in general and may interact with opportunistic pathogens’ growth. Therefore, a better understanding of microbiomes in domestic hot water installations is needed. The researchers used state-of-the-art methods
to delve into these microbial ecosystems, including fl ow cytometry and 16S rRNA gene amplicon sequencing. The BactoSense fl ow cytometer, a key tool in the study, allowed the team to quickly and accurately analyse and compare bacterial communities in hot and cold water, providing crucial data for understanding these unique environments. In a recent interview, Thomas Egli recounted how the study began serendipitously when he discovered unusually high cell counts in hot water using a BactoSense device. This unexpected fi nding spurred further investigation and collaboration with bNovate Technologies and other researchers. The research highlighted signifi cant diff erences in microbial
communities between hot- and cold-water systems, emphasising the need for more comprehensive knowledge and, if necessary, regulations, concerning
microbiology in domestic hot-water installations, not only for legionella. Egli explained that hot water systems act like
bioreactors, producing nutrients that promote microbial growth. The study confi rmed that hot water microbial communities diff er distinctly from those in cold water, the former being dominated by a few thermophilic strains. Flow cytometry and gene analysis validated these fi ndings, underscoring the importance of understanding the stability and vulnerability of these ecosystems to pathogens. He highlights the eff ectiveness of fl ow cytometry
tools like BactoSense for monitoring these systems, off ering rapid insights into abundance and diff erences in microbial communities. Further research could explore the interactions between thermophilic bacteria and pathogens like Legionella pneumophila and establish more eff ective hot water system guidelines.
DAIKIN JOINS FORCES WITH LAURENCE LLEWELYN-BOWEN ON HEAT PUMP AWARENESS
D
aikin UK has teamed up with Laurence Llewellyn-Bowen in a campaign to raise consumer awareness of heat pumps. The
campaign, called Modern Home Must Haves, will run until the end of the year and seeks to position heat pumps as a key component of every low- carbon home. The campaign is underpinned by research that surveyed 2,000 homeowners and renters about their expectations of a modern home. The research, which explores how our expectations have evolved over recent years, revealed that attitudes are changing. People are becoming
more conscious of their home’s impact on the environment and are looking for diff erent features in their ideal property. Commenting on the fi ndings Laurence Llewellyn
Bowen said: “This research shows how what we want from our homes is changing. People are not only thinking decoratively but also environmentally when it comes to what they want their home to be like, and what it says to others. Many of the ‘modern home must haves’, like heat pumps, are thoughtfully designed and can be incorporated seamlessly into homes without compromising on style.” Iain Bevan, Residential New Business Director at
Daikin UK said: “The research clearly shows that that homeowners and renters are becoming more environmentally aware. However, the Government needs to work with the industry to educate people about the benefi ts of heat pumps and to address many of the myths about them. The heat pump industry hasn’t got the resources to do this on its own.”
6 September 2024
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