WATER SAFETY
My chemical romance: Rethinking water safety
Healthcare water systems are complex environments where microbial growth can pose serious risks to patients and vulnerable users. Dr Cathy Whapham, Dr Jimmy Walker, and Dr Vicky Katsemi explore the limitations of biocides, highlighting that design, materials, installation, and ongoing maintenance are critical to controlling waterborne pathogens.
Whilst temperature is the primary method of microbial control in healthcare building water systems, poor design, inappropriate materials and a lack of effective maintenance results in proliferation of waterborne pathogens and formation of biofilms within the water network. As a result, water sources can present a risk to patients and vulnerable users. Biocides are often considered an alternative control
strategy to reduce the presence of biofilms and waterborne pathogens in healthcare water systems. However, the use and application of biocides must be tailored to each individual building and water system. This article discusses how biocide use does not overcome the inadequacies in design, construction, installation, operation and maintenance and hence they often fail to control the presence of pathogens. Whilst biocides may be seductive, their use and unintended consequences may end in heartbreak.
Operational control of hot and cold water systems in healthcare facilities Provision of hot and cold water is required in healthcare buildings for cleaning, hand washing, showering, bathing, food preparation, birthing pools and laundry. Hospital water systems are large and complex and whilst water delivered to hospital sites is “wholesome”, once water crosses the threshold, conditions change dramatically which deteriorates water quality.1
Water can be stored in
large tanks to maintain a continuous supply to all water services and equipment installed downstream. As outlets are used, water is drawn through pipework which will contain different material types and a range of equipment including calorifiers, expansions vessels, pumps, valves and taps. Water will either be continuously moving or under stasis (not moving) within the pipework. Static water at the periphery of the water system, quickly adopts ambient temperature (typically within 30 minutes even in well insulated pipework). The presence of a large surface area and a combination of temperature changes, stagnant water, aged water and a ready supply of nutrients in extensive and complicated pipework systems are the perfect conditions for microorganism colonisation and growth. Whilst the majority of microorganisms within a water
system are harmless, Legionella spp., Pseudomonas spp., Stenotrophomonas spp., Klebsiella spp., Serratia spp., non-tuberculous mycobacteria, Acinetobacter spp., are recognised as waterborne pathogens commonly associated with healthcare water systems.2
These waterborne pathogens will colonise surfaces and form
Top: Corrosion, bacteria and damage can all affect hospital water systems. Middle: Detailed view of formations on a surface. Bottom: Significant corrosion inside a copper pipe.
January 2026 Health Estate Journal 35
biofilms consisting of layers of bacteria, amoeba, fungi with associated sediments embedded in a hydrated network.3
As outlets are used, pressure fluctuations release
microorganisms and particulates from biofilms into the water stream and contaminating users, equipment and drains. Patients are exposed to pathogens via direct water contact, splashing or aerosolisation leading to outbreaks (healthcare associated waterborne infection).4 Temperature is used for microbial control in water
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