From compliance to continuous control: Managing risk in cold water storage
Richard Braid, Managing Director of Keraflo, discusses why accurate monitoring and proactive management of cold water storage systems has become a critical priority for building services engineers.
Cold water storage tanks remain a fundamental component of many commercial and public buildings. Whether supporting boosted supplies in healthcare environments, ensuring resilience in education estates, or serving large residential schemes, stored water plays a vital yet often overlooked role in overall system performance. However, in the context of rising Legionella cases and increasing scrutiny of water hygiene management, reliance on periodic inspection alone is no longer sufficient.
UK Legionellosis cases have risen significantly in recent years, and outbreaks continue to surface across a range of building types. While awareness of Legionella risk is well established within the industry, effective and demonstrable control still remains inconsistent. The issue is not a lack of guidance, but the practical challenge of maintaining optimal conditions in dynamic building environments where occupancy patterns, usage profiles, and system ageing all influence risk.
Legionella bacteria proliferate in water temperatures between 20°C and 45°C, particularly where stagnation occurs. For stored cold water, maintaining temperatures below 20°C is critical, and in theory, this appears straightforward. In practice, it is influenced by tank location, insulation standards, plantroom conditions, pipework configuration, turnover rates, and seasonal variation. Even well-designed systems can drift outside optimal parameters if usage reduces or control mechanisms are inadequate.
Visibility
One of the most significant challenges facing building services engineers is visibility. Traditional float-operated cold water storage systems provide limited insight into real-time operating conditions. A tank may appear serviceable during inspection, yet temperature stratification, extended retention times, or intermittent supply patterns may be creating ideal conditions for bacterial growth. Manual checks, while essential, cannot provide continuous visibility of system performance.
Modern building operation demands something more continuous and data-driven. Engineers are increasingly being asked not simply to design compliant systems, but to demonstrate ongoing control. In healthcare and local authority settings in particular, audit trails and proof of risk mitigation are becoming just as important as physical infrastructure.
Temperature management is central to this. Stored water must be protected from ambient heat gain, particularly where tanks are located within plantrooms that also house calorifiers or other heat-generating equipment. Insulation should be correctly specified at design stage and maintained in operational condition if temperature control is to remain effective. However, insulation alone does not guarantee compliance, and where turnover is low, water can remain static for extended periods, gradually warming into the Legionella growth range despite adequate initial design.
Water demand profiles
Post-pandemic hybrid working models, seasonal education closures, and fluctuating commercial building usage have fundamentally altered water demand profiles, exacerbating the risk associated with stored water systems. Configurations originally sized for consistent daily draw-off may now experience prolonged periods of reduced demand. Oversized storage volumes, once considered good engineering practice for resilience, can inadvertently increase stagnation risk.
This is where intelligent monitoring and adaptive control become essential. Rather than relying solely on periodic manual intervention, electronic management systems can provide continuous oversight of temperature and water level conditions. By actively managing stored volumes in line with demand, these systems reduce unnecessary retention and improve turnover, limiting opportunities for bacterial development.
The ability to trigger staged alerts if temperatures rise beyond acceptable thresholds is also critical, and early warning allows facilities teams to intervene before risk escalates. More advanced systems can be configured to initiate corrective action automatically if initial alerts are not addressed, ensuring that control does not depend solely on human response times.
Importantly, such approaches align with the intent of HSE guidance and ACOP L8, which emphasise proactive management and demonstrable risk control. Compliance is more than just reacting to laboratory results; it is about designing and operating systems that minimise the likelihood of conditions conducive to bacterial growth.
Another factor often underappreciated is the relationship between tank sizing and system resilience. Engineers must balance the need for adequate supply security with the imperative to avoid excessive stored volume. Right-sizing, informed by realistic usage modelling, rather than legacy assumptions, is increasingly important in both new-build and refurbishment contexts. Where full system redesign is impractical, retrofit monitoring solutions can help mitigate inherent constraints within existing infrastructure.
Asset longevity
From a lifecycle perspective, improved monitoring also supports asset longevity. Maintaining stable water levels and avoiding repeated mechanical stress on valves and fittings reduces wear. Early identification of abnormal conditions can prevent more serious downstream issues within distribution pipework and boosted systems. In this way, water hygiene management and mechanical reliability are closely linked.
As digital management becomes embedded across building services and expectations around performance accountability increase, stored water infrastructure must be afforded the same level of oversight as other critical systems. HVAC, lighting, and energy performance are now routinely integrated into building management system (BMS) platforms to provide continuous monitoring and control; water storage should be treated no differently. Real-time data visibility, trend analysis, and responsive control have to form part of core building services strategy, rather than being viewed as supplementary enhancements.
Keraflo focuses on the management of cold water storage tanks, and its electronic Tanktronic system represents one approach to achieving this level of oversight. The system monitors temperature and manages water levels, providing facilities teams with greater visibility of tank conditions and alarm functionality to flag potential issues. Adjustable settings, including a holiday mode, allow stored volumes to be aligned more closely with occupancy patterns, helping to reduce unnecessary water retention.
However, regardless of the specific solution selected, the underlying principle remains consistent: effective risk control begins at the point of storage.
Beyond static compliance
Effective Legionella risk management depends on embedding intelligent control into the design and operation of water systems so that risk is inherently minimised. For building services engineers, this means moving beyond static compliance thinking towards continuous performance management.
Cold water storage may sit quietly above ceilings or within plantrooms, but its impact on occupant safety and regulatory exposure is significant. In an environment of rising case numbers and increased scrutiny, accurate monitoring and proactive management are no longer enhancements; they are essential components of responsible building services engineering.
