WATER HYGIENE AND SAFETY – SPECIAL REPORT


requirements of regulations made under Section 67 (Standards of Wholesomeness) of the Water Act 1991. Note: In terms of microbial quality, there should be very little risk from pathogens in the water that is provided by your water supply company. As soon as the mains water enters the building, responsibility for quality is immediately transferred to the landlord/ owner of the building (e.g. the Trust’s CEO). At the same time as water enters the smaller diameter pipework, the risk from waterborne infection increases considerably. Water will be used for cold water storage, hot water storage, and for auxiliary services throughout the hospital, and all water storage for domestic purposes should meet drinking water quality.


However, from the very first point of entry into the buildings, the drinking water quality will start to deteriorate from a microbiological perspective. The principles of managing a water system include keeping the cold water <20˚C and the hot water >55˚C, thus necessitating keeping the water moving.20


From the


perspective of bacteria, once they have gained entry to the water system, they want to be kept warm, gain a foothold on a surface (biofilm formation, which will depend on the type of material and speed of water flow), and ideally have access to extra nutrients to support growth.


Figure 1 presents an overview of some of the inherent microbial risks in water systems, and some of these topics will be expanded. n Once the wholesome water from your water supply company enters a building, the responsibility for the quality of that water transfers to the owner/landlord, and the quality of the water will start to deteriorate, leading to the growth of different pathogens.


n As a hospital is built, components that are delivered and assembled need to be delivered to the site clean and free from waterborne pathogens, and handled in a hygienic way to prevent water and dirt, i.e. microbial nutrients, from entering pipes (e.g. capped) and components prior to assembly. Manufacturers and suppliers must play their part in the provision of a hygienic and safe water system by providing WRAS-approved components – see panel right.4


is carried out, precautions should be taken to prevent the growth of microbial pathogens, e.g. microbial monitoring of the components and disinfection if required.


n While hospitals need to be designed from first principles to control the growth of microorganisms in a water system, over time, new developments, extensions, and refurbishments, will take place, and these too need to be


built into consideration for microbial control. If not, contamination will occur when ‘old’ and ‘new’ infrastructure are connected.


n Plumbing components have to be microbiologically safe when connected to a water system. A number of plumbing components and valves are inherently complex, and need to be tested for efficacy prior to shipment. Where components are wet tested by the manufacturer, they then need to be decontaminated prior to delivery to prevent microbial and biofilm contamination..21


n Water cisterns are where the cold water is stored, and one of the first places that water quality starts to deteriorate, and biofilms containing pathogens begin to develop. Cisterns should be sited where the temperature can be maintained at <20˚C and heat gain prevented, as this will encourage microbial growth. The inlet and outlet should be at opposite sides of the cistern, to ensure sufficient mixing. The cistern should be sized appropriately, such that there is only 12 hours’ worth of on-site storage;


otherwise stagnation will occur, and an appropriate type AA air gap provided to prevent retrograde contamination. The cistern should be kept clean, with well-fitting lids with seals, and protected vents, used to prevent dirt and nutrients from entering it. Hollow supports for the lids have previously led to biofilm development, and seeding of the water network with Legionella and P. aeruginosa.20


n Hygienic maintenance is required at all times when working in high dependency units, and engineering staff need effective training to ensure they understand the basics of hygiene, and the potential for microbial contamination if they do not undertake tasks hygienically. Fitters, plumbers, and engineers, should receive training in hygienic practices, including on using clean tools not previously used on contaminated procedures, e.g. for unblocking toilets, without being decontaminated.


n Contamination of peripheral components, for example outlets, by poor cleaning practices by domestic


Where manufacture testing


What is Water Regulations Advisory Scheme (WRAS) approval?


WRAS checks the testing of thousands of water fittings products to ensure they comply with the Water Supply (Water Fittings) Regulations and Scottish Byelaws. The water fittings regulations protect drinking water supplies, and impose a legal duty on everyone to use suitable water fittings (pipes, fittings, taps, showers) when connecting to public water supplies. Non-metallic materials are considered suitable, if they pass appropriate material and mechanical regulatory performance tests, including not promoting the growth of microorganisms (BS 6920).


December 2020 Health Estate Journal 17


Figure 4: Microbial fouling of the outlet fitting, flow straightener, and associated coupling.


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