WATER QUALITY
There is nothing wrong with this principle. In many cases, it is essential. The difficulty lies in implementation. Manual flushing
programmes rely on people, and people work in real organisations under real pressures. Staff need clear responsibility, sufficient time, access to outlets, reliable records, and a process that can actually be sustained week after week. In a large estate, that is no small ask. It is one thing to say that every low-use outlet should
be flushed at the required interval. It is another to achieve that consistently across a changing hospital footprint with competing priorities, staffing constraints, refurbishments, and intermittent service disruption. This is not an argument against flushing. It is an argument against pretending that flushing is easy. In practice, the more complex the estate, the more important it becomes to distinguish between policy and dependable delivery. A flushing regime is only as good as its execution. Where manual regimes are difficult to sustain, additional support may be needed if organisations want the control measure to be more than aspirational. That is where automated support can enter the
conversation in a reasonable, non-dramatic way. In areas with persistently low use, temporary closures, phased openings, or awkwardly located outlets, automated flushing can help maintain turnover more consistently than a regime that relies entirely on busy teams remembering and recording every action. Used well, it is not a substitute for good system design – it is a practical way of supporting intended operation where the estate itself makes consistency difficult.
Water age, design, and the reality of mismatch The concept of water age is useful here. The longer water remains in a system, the greater the potential for changes in its characteristics – driven by temperature, materials, nutrient availability, and hydraulic behaviour. In complex buildings, water age can vary significantly between outlets. This is where design and operation intersect. Systems may be sized for demand that never materialises, include capacity for future expansion, or be affected by changing clinical use. Components such as expansion vessels or dead ends can create areas of poor turnover, even where the wider system appears to function adequately. NETB No.2024/3 is explicit on several of these issues
in higher-risk settings. It stresses the need for design with no potential for stagnation, hot water delivery that reaches safe temperatures quickly, wastewater arrangements that do not allow standing water or backflow, and collection points that avoid contamination from splashing and drain contact. That emphasis is important because it recognises a reality often missed in day-to-day discussion: stagnation is not always a maintenance problem that can be corrected later. Sometimes it is built into the way the system has been conceived, sized, or adapted. It is also one reason why overly simple advice can be misleading. ‘Just flush it’ may be useful as an immediate instruction, but it is not a strategic answer where the underlying issue is a system that no longer matches building use. In those cases, stagnation is a symptom of a deeper misalignment between design assumptions and operational reality.
Looking beyond the tap For many years, the dominant conversation around water hygiene centred on the supply side: incoming water, stored water, calorifiers, distribution temperatures, little- used outlets, showerheads, and terminal fittings. All of that
Across modern healthcare estates, water regularly sits idle. Taps are used less often than expected. Clinical areas are refurbished, decanted, or repurposed. Rooms may stand empty for days, sometimes weeks.
remains important. But it is no longer enough. Increasingly, attention is also being directed to the
drainage side of the system, and with good reason. Sink drains, traps, and siphons are microbiologically active environments. They contain moisture, nutrients, and surfaces well suited to biofilm formation. In hospitals, they can become persistent reservoirs for Gram-negative organisms and other water-associated pathogens. This is not just a laboratory curiosity. It has direct relevance to clinical risk, especially where sinks are close to patient activity and hand hygiene. The key point is that the drain is not separate from the care environment simply because it sits below the basin. Under the right conditions, what grows there does not necessarily stay there. That matters because healthcare has historically been more comfortable discussing supply-water hygiene than wastewater-associated risk. Yet the patient does not experience those systems as separate worlds. They meet at the washbasin, the shower, the sink, and the surrounding care environment. From the patient’s perspective, the distinction between ‘fresh water side’ and ‘drain side’ is
Room air
Figure 4: Biofilm-driven aerosol formation in sink drainage systems.
Aerosol cloud 0 = 1.5m
Gases from the wastewater pipe Biofilm
Biofilm
Water seal
Free-floating microorganisms, pyro-gens 103
–109 CFU/ml August 2026 Health Estate Journal 43
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