Cold-water storage tanks rarely draw attention until something goes wrong. Tucked away in plant rooms, they play a critical role in maintaining water hygiene.
If tanks aren’t managed properly, the risks build quickly: stagnation, bacterial growth, insufficient turnover and unnoticed temperature changes can all create ideal conditions for Legionella to develop. Preventing these issues is essential for occupant safety and system reliability.
Different building types face different challenges. Healthcare sites, for example, require tight legionella control because of vulnerable residents. Schools and universities must contend with seasonal occupancy, making automated scheduling valuable for reducing stagnation during holidays. In commercial offices, hybrid working patterns mean water usage can fluctuate week to week, leaving tanks oversized for actual demand.
UK health and safety law requires building owners and managers to control legionella within water systems, with the HSE’s L8 Approved Code of Practice and HSG274 guidance forming the recognised approach. Following L8 is not mandatory, but it is considered the reliable way to demonstrate compliance and meet legal responsibilities.
In many buildings, tank oversight still depends on manual checks. These checks take time, rely on staff availability and only ever provide a snapshot. It can mean temperatures drift into the danger zone unnoticed and stored water sits far longer than intended.
Divided tanks present additional challenges. While both sides continue to turn over via the balance pipe, demand can be met consistently by a single inlet valve. Over time, this uneven loading can create conditions where water movement is reduced in part of the system, increasing the risk of stagnation and biofilm formation if not actively monitored.
MECHANICAL SOLUTIONS
Keraflo has long focused on mechanical solutions that support better water turnover and control. Unlike an equilibrium valve that refills gradually, its Aylesbury KB Type delayed-action float valve waits for the water level to fall to a user-set point before opening fully. This ‘all or nothing’ approach fills the tank at maximum flow, turning the water over more effectively and reducing the semi-stagnant period. Once the tank reaches the correct level, the valve closes fully.
For divided tanks, the KP Twin Float Valve Kit provides an extra layer of protection. Using KB Type pilot valves in each compartment, the system ensures that whichever section drops first triggers the main control valve. Both sides then fill together, preventing an imbalance and reducing the likelihood of stagnant biofilms forming.
Mechanical devices can significantly improve tank health on their own, but electronic control is becoming increasingly important, especially on large or variable-use sites. Keraflo’s Tanktronic system brings monitoring and management into one platform, using sensors to track water levels and temperatures in real time.
If readings drift out of range, there is a first stage ‘alert’. If there is no response, a second stage ‘override’ can take evasive action. In buildings where demand fluctuates, Tanktronic’s ‘holiday’ schedule allows users to reduce stored water volumes during periods of lower demand, helping to limit extended storage times and the risk of stagnation. Remote access lets managers monitor conditions without needing to enter the plant room.
As estates become more complex and occupancy less predictable, relying on manual checks alone is no longer sustainable. Effective tank management is however, essential and achievable. Intelligent systems, supported by robust mechanical components, offer a straightforward route to consistent water quality, reduced risk and more efficient maintenance planning. www.keraflo.co.uk