With legionella once again making headlines in England and Wales, HVP spoke with industry experts to discuss the causes of Legionnaires’ disease and what can be done in domestic and commercial properties to prevent its rise.
Legionella is a hot topic in the heating and plumbing industry. But what is it, and what risks does it pose? According to the Health and Safety Executive (HSE), “Legionnaires’ disease is a potentially fatal form of pneumonia and everyone is susceptible to infection”.
It is caused by the growth of legionella bacteria in natural water sources such as rivers and lakes, and in purpose-built water systems. For instance, legionella bacteria can grow in spa pools, shower heads, and evaporative condensers.
People can contract the potentially fatal disease by breathing in small water droplets (aerosols), which are suspended in the air and carry the bacteria. There are certain conditions which make the growth of legionella bacteria more likely. For example, it thrives in temperatures between 20-45°C. There are also certain deposits such as rust, sludge, and scale which can support bacterial growth by providing a source of nutrients. Additionally, where water is stored and/or recirculated, the bacteria has the potential to grow.
While everyone can contract the disease, there are those who are more vulnerable and therefore at higher risk. The HSE states that people over 45 years of age, smokers, heavy drinkers, people suffering from respiratory or kidney disease, diabetes, lung, and heart disease, as well as anyone with an impaired immune system, are all at greater risk of falling victim to the disease.
“The presence of bacteria, particularly legionella bacteria is common within water sources. This means that under certain conditions, bacteria have the potential to grow in manufactured water systems,” Alan Clarke, Technical Support Manager at Heatrae Sadia, explains. “The threat to persons in high risk groups, such as the infirm or those with respiratory problems, is elevated – if exposed to legionella bacteria, Legionnaires’ disease can develop, resulting in severe respiratory illness or even death.”
It’s possible many installers will likely never have heard of the Monthly Legionella Report. This report, issued by Public Health England, is a national surveillance scheme that monitors and tracks cases of Legionnaires’ disease in England and Wales. The June 2019 report evidences 156 confirmed cases of Legionnaires’ disease since 1 January 2019, with 53 of those cases having been reported in June 2019.
Steve Saunders, Senior Technical Manager at Triton Showers, believes that the eradication of legionella is possible, but not without education.
He said: “Eradicating legionella in man-made hot and cold-water systems is possible but requires a level of education that simply doesn’t exist within all our homes and businesses.”
The risk of bacterial growth can change dependent on how often the water system is used. Steve explained: “In the home, the everyday use of water systems means that there is a relatively low risk; particularly where water is mains-fed and heated via a combi boiler or electric shower. Where there is a potential increased risk, is in any disused areas of the property, such as a guest en-suite, following an extended break away, or perhaps in a tenanted property that’s been vacant for a period of time.”
Managing the risk of legionella is a priority for manufacturers in the heating and hot water industry. Indeed, many continue to provide installers and homeowners with the necessary advice to mitigate against bacterial growth.
“If in doubt, the advice is to flush through any unused taps, showers, and pipework to help mitigate against the risk and ensure there is no water sitting or stagnating in the system, thereby removing any potential bacteria source,” Steve said.
Other manufacturers, such as Heatrae Sadia, have developed their products with legionella in mind. For example, “in hot water storage systems, such as cylinders, water is generally stored and distributed at 60°c or above,” Alan explained. This is because, once the temperature hits 60°C or above, the legionella bacteria die.
There are additional measures that homeowners can take that are relatively simple, as Steve highlights: “Other easy maintenance measures would be to regularly clean showerheads to ensure normal water flow and check shower hoses for damage or kinks to prevent water pooling.”
For those in the commercial world however, legionella can also be highly problematic, not only for the protection of the reputation of the business, but also in safeguarding the public. David Ridgway, Product Application Manager at Andrews Water Heaters, explained: “The risk to public health is wholly avoidable, fatalities and sickness caused by this disease need not occur. For instance, the recent fatality in a hotel in Ludlow, along with the case of a member of the public contracting Legionnaires’ in a leisure centre in Tendring, could have been avoided had adequate water management been in place.”
The management of legionella is not without its risks however. The storage and distribution of water at 60°c from a cylinder can in itself result in injury to the end-user.
“With water at 60°C being able to cause partial thickness burns in about five seconds, tackling legionella bacteria carries a higher risk of end-user injury if precautions are not taken,” added Alan.
For Alan, the solution to this challenge is simple, use a thermostatic mixing valve to control the temperature at the point of use. This is because they “reduce the discharge temperature of stored hot water to an appropriate level by blending it with cold water before it reaches the tap, ensuring a constant and safe outlet temperature".
A burning question for many within the industry is whether more can be done to tackle the problem of legionella before the system is installed and commissioned. Indeed, there are those who challenge designers and specifiers to do more to protect public health prior to installation.
“Designers, specifiers, contractors, and facilities managers all have a role to play in protecting public health,” said David. “This begins by designing, maintaining, and operating water services under conditions that control the risk of legionella.
“By correctly designing the pipe runs in the first instance, combined with the correct use of controls and interfacing of the water heater and associated pumps, this can help to further reduce such risks. Once installed and commissioned, ongoing servicing, maintenance, and water treatment can help to control the bacterial growth in water heating appliances and components in the system. These include showerheads in gyms and spas, expansion vessels, and thermostats.”
For Alan and David, a linked up approach at the design stage can help to mitigate against the challenges posed by bacterial growth. As Alan explains, “the heating industry must remain vigilant and work with designers, architects, specifiers, contractors, and facilities managers to reduce the risk of legionella”.
Furthering this belief, David said: “Investing in equipment and appliances that can work in tandem with existing legionella risk management plans can help to mitigate against bacterial growth.”
It is clear that tackling legionella is not the job of one profession, everyone in the heating and plumbing industry has a role to play in ensuring that the design, installation, and commissioning of a water system is adequate enough to fend off the risk of bacterial growth and distribution.
While specifiers, designers, and installers must play their part, so too must the homeowners and end-users. This will only be possible if the heating and plumbing industry is prepared to do more to educate the public.
“Prevention is better than the cure and if some simple maintenance tasks can help prevent further cases of Legionnaires’ disease, then surely it is a worthwhile task and industry must help to further educate the market,” Steve concluded.
Legionella can be eradicated, but this will take effort and hard work from all parties – from installers, to specifiers and homeowners. This is a wholly avoidable disease, but as the Monthly Legionella Report indicates, there is still much more work to do. With 156 cases of legionella already recorded this year alone, the time for action is now.
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