Many people ask us about Anti-Legionella Valves, often drawn in by their eye-catching name. But do they truly prevent Legionella bacteria from growing in water systems? Let’s break it down.
What Do Anti-Legionella Valves Actually Do?
These valves help reduce the risk of Legionella by promoting continuous water movement with expansion vessels, which helps to prevent stagnation—a key factor in bacterial growth. However, for some, their name implies that the valves go further, somehow providing continuous protection against the growth of the bacteria.
The Key Limitations of Anti-Legionella Valves
No Active Disinfection
Flow-through valves keep water moving, but they don’t contain built-in disinfection methods such as UV treatment, chemical dosing, or thermal control, which are required to kill Legionella bacteria directly.
Limited System-Wide Impact
While they reduce stagnation at specific points, they don’t address risks elsewhere, such as dead legs (unused pipe sections) or poorly insulated areas where temperature control may fail.
Minimal Temperature Control
Legionella thrives in water temperatures between 20°C and 45°C. These valves do not regulate water temperature, meaning they cannot ensure conditions remain outside the bacterial growth range.
No Biofilm Prevention
Flow-through valves may reduce stagnation, but they don’t prevent biofilm formation—the slimy layer inside pipes where Legionella can multiply. Biofilm control requires regular cleaning and disinfection.
A Holistic Approach is Essential
To truly control Legionella risk, you need a comprehensive water management strategy, including:
Temperature control (keeping hot water above 50°C and cold below 20°C)
Regular system flushing
Chemical or thermal disinfection protocols
Proper plumbing system design and maintenance
The Bottom Line
Flow-through valves, often marketed as "Anti-Legionella" valves, are useful in minimising risk but should not be relied upon as a standalone solution. Effective Legionella prevention requires a combination of strategies, not just one component.
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Drop us a line and one of our friendly team will be happy to help…. https://www.titanmechanicalservices.co.uk/contact
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