Sensor‑operated taps have become increasingly common across commercial, public, and even residential buildings. Their touch‑free design appeals to modern expectations of hygiene, accessibility, and convenience, while also helping reduce water waste through controlled, on‑demand flow.
From office washrooms and healthcare facilities to hotels, gyms, and schools, sensor taps are often viewed as a simple upgrade that improves both user experience and environmental performance.
However, like any part of a water system, sensor taps come with important operational considerations. While they offer clear benefits, they can also affect water movement and temperature control in ways that may increase risk if not properly understood and managed.
How Sensor Taps Influence Water Use
Traditional manual taps are typically used for longer periods, such as when washing hands, filling containers, or cleaning. Sensor taps, by contrast, only run when a user's hands interrupt the sensor. While this reduces unnecessary water use, it can also significantly shorten flow duration. In some cases, outlets may only run for a few seconds at a time.
This reduction in flow has several effects, including less frequent flushing of the pipework, shorter periods of water movement through individual outlets, and a reduced overall turnover of stored or distributed water. Over time, these conditions can allow water to stagnate within the system, especially in areas of a building where usage is already low.
Hybrid Working and Underused Outlets
Many modern office buildings now operate with hybrid or flexible working patterns. As a result, occupancy levels vary dramatically throughout the week. Floors, wings, or entire sections of a building may go unused for days at a time.
Sensor taps in these areas may only activate once or twice a week, meaning water sits dormant within pipework. When water remains still, temperature control becomes unreliable. Both hot and cold water can drift from safe operating ranges, creating conditions where bacteria such as Legionella can proliferate.
In the UK, HSG 274 Part 2 provides guidance on managing these risks, including the expectation that infrequently used outlets should be flushed weekly to maintain healthy water movement. This remains one of the most effective and straightforward mitigation measures for preventing stagnation and ensuring temperature regulation.
Why Stagnation Matters
Stagnant water is more than just an operational concern — it is a recognised water safety risk. Without regular movement, disinfectant levels drop, temperatures change, and biofilms can develop. These conditions support the growth of harmful microorganisms, including Legionella pneumophila, which is responsible for Legionnaires’ disease.
When sensor taps operate infrequently, the short bursts of flow are often insufficient to draw fresh water through the system. This means that even “active” outlets may still harbour stagnant water behind the tap body or within associated pipework.
Managing Risk Through Smart Design and Maintenance
The good news is that sensor taps can remain safe and effective when paired with appropriate maintenance and thoughtful system design. Key strategies include:
- Flushing Regimes:
Implement weekly flushing regime of all infrequently used outlets, in line with HSG 274 Part 2. This helps maintain water movement and correct temperature distribution. - Automated Flushing Functions: Many modern sensor taps now include programmable flushing features. These automated cycles periodically run water through the system, ensuring regular turnover even in low-occupancy environments. This reduces reliance on manual flushing and supports consistent control.
- Temperature Management: Ensure that hot and cold water systems maintain temperatures within safe ranges and that thermostatic mixing valves (TMVs) are serviced regularly.
- System Design Considerations: During installation or refurbishment, consider pipework routing, dead‑legs, and outlet positioning to reduce areas where water may sit unused.
In healthcare, if automatic flushing is to be adopted, its potential impact on patients’ sleep patterns and the disturbance of mental health patients should be considered.
Conclusion
Sensor taps offer real advantages: improved hygiene, reduced waste, and a modern user experience. But like all water system components, they are not “fit and forget” solutions. Without proper management, their reduced flow and intermittent use can create conditions that encourage stagnation and bacterial growth.
Feel free to reach out if you have any questions about the issues mentioned above or if you would like to consult with one of our experts on water hygiene.
Editor's Note: The information provided in this blog is correct as of the date of original publication - April 2026.
© Water Hygiene Centre 2026
