WATER SYSTEM SAFETY
No one treatment regime can fully ensure effective control in every case. Factors such as age, design, size, and water chemistry, will dictate the best mix of measures for a given installation.
Temperature
Hot and cold water systems should be maintained to keep cold water, where possible, at a temperature below 20˚C, and keep hot water stored at 60˚C and distributed so that it reaches the outlets at 55˚C within one minute. To reduce the risk of scalding, thermostatic mixing devices are required for specific hot water outlets. Maintaining optimum temperatures is an effective way to manage the risk of Legionella and other microbes developing in water systems; it is a control that is widely used in many large premises settings. However, the major challenge in temperature-based regimes is ensuring that the appropriate temperature ranges are maintained in hot and cold circuits. Complex water systems in environments such as a hospital will need dependable, comprehensive monitoring to ensure effective management of water temperatures.
With the development of digital technologies, temperature control monitoring and reporting has become much more reliable as an antimicrobial measure. Temperatures across water systems can be remotely monitored in real time, and kept within safe limits with more precision than via traditional monitoring techniques.
Reports alerts, and data
DVS Inform is an example of how far this technology has come. Along with accurate monitoring of water temperature, the overall solution can also provide reports, alerts, and data to a PC, mobile phone, or tablet.
Biocides
Introducing biocides to water systems to prevent bacterial growth must be done under strict controls and monitoring – for the treatment to be effective, and for the
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electrodes. The resulting ionisation in the water is proven to be effective in controlling Legionella, and also has the effect of penetrating and controlling biofilms which may be present inside pipes and vessels. This ionisation technique can be affected by water softening systems, so in hard water areas checks for suitable ion levels should be more regularly performed. In all cases, such samples must be analysed by a UKAS-accredited lab.
DVS’s Inform real-time temperature monitoring offers a digital way to maintain constant oversight of water system assets, “by feeding accurate data ‘24/7’ to a secure cloud-based platform”.
water to remain safe for users. In some circumstances, the use of biocides may not be appropriate – for example, in healthcare premises where renal and haemodialysis treatments are carried out. It is recommended that national water supply (water quality) regulations are thoroughly consulted before any biocidal treatments are selected and applied. Some of the available biocidal systems include: n Chlorine dioxide – this oxidising biocide/disinfectant is a useful option for Legionella control in hot and cold water systems. It is often applied where maintaining an effective temperature against bacterial growth is not possible, and on sites where removing redundant pipework is not practical, or sections of the system are used infrequently.
n Copper and silver ionisation – this is an electrolytic treatment in which a low electrical current is passed through the water between two copper and silver
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n Chlorine – most mains water supplies rely on low levels of chlorine for water safety in distribution networks. Once within a premises’ water system, this may not be enough to control Legionella, and additional dosing can be required. Chlorine’s effectiveness is dependent on several factors – chlorine concentration, pH values, temperature, amounts of organic material, contact time, and the number and types of bacteria present.
n Silver-stabilised hydrogen peroxide – silver hydrogen peroxide has been shown to be a good means of control against Legionella, when applied and maintained as instructed by the manufacturer. However, it is not to be used in systems supplying dialysis units.
Additional measures
Point-of-use (POU) filters are intended to prevent bacteria and parasites from exiting outlets such as taps and showers. They are generally used on a temporary basis while more permanent solutions are selected and adopted. POUs also trap any dislodged biofilm within the system. Their efficacy is largely dependent on replacement scheduled by the manufacturer’s instructions. UV and ozone treatments are a further additional control option – but these are only effective at or close to the treatment point. This makes their performance difficult to measure in terms of their residual effect. Several treatment points may need to be installed. In summary, while there are many options available to address the threats posed by waterborne pathogens, currently the most
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