WATER HYGIENE AND SAFETY
system must minimise the risk of colonisation, and inhibit the development of waterborne pathogens. Flexible hoses made from EPDM (ethylene propylene diene monomer) have long been a cause for concern. Their pitted interior surface provides niches where bacteria can adhere, and biofilm develop. Unable to withstand repeated chemical and thermal shocks, they disintegrate over time, releasing debris into the system which supports bacterial development. The BSI Code of practice2
states that the risk assessment
should identify where flexibles are the only option, and inappropriate materials should be replaced with PEX-lined hoses.
Keeping users safe Complex systems lead to temperature drops and increase the contamination risk. As with Legionella, keeping the hot water hot (HTM 04-01 Part B4
recommends
circulating hot water above 55°C), and keeping water flowing, will reduce the risk of P. aeruginosa proliferation. The challenge is ensuring user safety. For intensive and critical care environments, non-TMV taps are advised due to a lower scalding risk (the user can be advised of the scalding risk via signage). In patient areas with an elevated scalding risk, type 3 TMVs with an anti-scalding failsafe are preferred. However, TMVs have been associated with colonisation because centralised blending can lead to cold water deadlegs, and, unless serviced regularly, strainers become a source of nutrients for bacteria, due to debris, scale, and biofilm build-up. Regular checks and servicing in line with manufacturer guidelines, reinforced by HTM 04-01 Part B,5
The spouts can be easily replaced by filter spouts on Delabie’s Bioclip mixers.
is particularly pertinent post-COVID, where hand sanitiser has replaced handwashing in some areas, leading to under-utilisation of handwash basins. As with showers, the P. aeruginosa risk assessment may advise the removal of certain handwash basins that are no longer used routinely.
will significantly reduce
the risk of contamination, and improve the longevity of the mechanism. Where patients require full body immersion, or vulnerable patients have been identified, HTM 04-01 Part C5 recommends POU TMVs such as the Securitherm mixer, which draws both cold and hot water, maintaining water flow. The guidance also recommends flushing on a daily basis, and sensor controls with an automatic duty flush will ensure that water circulates through the system. This
Maintaining the flow Automatic taps with a periodic duty flush have also been identified as a potential source of P. aeruginosa. Contamination occurs at two levels – in the flow straightener, and in the solenoid valve which opens and closes the flow. In some models, water becomes trapped behind the diaphragm in the solenoid valve, leading to stagnation. The diaphragm itself can provide a source of nutrients which promote bacterial proliferation. Delabie’s Tempomatic sensor taps feature a piston- operated solenoid valve which refreshes all the water in the valve with every activation, preventing any stagnation. The integrated anti-bacterial flush occurs every 24 hours after the last use to refresh the water in the tap (including the diaphragm), and the pipework. With flow-straighteners, the associated
risk of contamination is such that BS 8580- 2:2022 recommends removing them in areas where there are high-risk patients. It says: ‘Inserts such as flow-straighteners and water-saving devices in taps [] have been shown to increase the risk of
colonisation significantly and transmission of PA infection and should not be present in augmented care areas.’2
Flow-limiters Flow-limiters contribute to water savings, but reduce flow, and increase the risk of stagnation. Water retention and scale build-up lead to splashing and aerosol generation, as well as offering ideal conditions for P. aeruginosa to develop. Free-flow outlets offer a lower risk alternative as, unlike flow-straighteners and limiters, they have no grid or partitions, so there is no water retention. Delabie’s Biosafe outlet is made from an acetal copolymer, which is very hard-wearing and resilient. Its ultra-smooth surface reduces scale build-up, and bacteria is unable to adhere.
Designing safe surfaces In addition to managing contamination and amplification, the risk of transmission must be controlled. Factors that increase transmissibility are design, behaviour, and operational practices. We have already considered the impact of design on contamination, but design also plays a role in supporting best practice. Kotay et al6
advocate strict adherence
to good hygiene practices, and diligent monitoring in high-risk environments. In patient care environments, sinks should be used exclusively for handwashing. BS
The Tempomatic sensor tap with piston-operated solenoid valve to prevent stagnation.
The Biosafe free-flow outlet minimises water retention and scale build-up.
October 2022 Health Estate Journal 49
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