Drinking water entering your building is safe. What happens after that is your responsibility.
In the UK, drinking water is treated and regulated to high standards before it reaches your building. However, once it enters your system, particularly where it is stored or distributed, maintaining its quality becomes the responsibility of the heat network operator.
Water is used every day for drinking, cooking, and washing. When it’s not properly managed, poor water quality can pose a direct risk to compliance, health, , and resident safety.
In this blog, we explore where risks arise within building systems and what operators need to do to stay in control.
For low-temperature hot water (LTHW) systems, please refer to our related blog: Water quality: The silent threat in your heat network- Insite Energy
Where risks originate in building water systems
Water only remains safe if the system it passes through is properly managed.
Drinking water, also known as mains or potable water, enters a building as a controlled supply. From there, it is stored, circulated, and distributed through tanks, pumps, and pipework before reaching residents.
Each stage introduces risk. Stagnation in low-use areas, temperature fluctuations, and poor system hygiene can all cause water quality to deteriorate. Over time, this can lead to bacterial growth, sediment build-up, and system degradation.
These issues are not always visible. Water may appear clear while underlying risks develop. What starts as a minor oversight can escalate quickly, affecting both compliance and resident wellbeing.
The key point is simple: responsibility does not end at the point of entry. It starts there.
What happens when drinking water quality is not properly managed?
The impact of poor water quality is not theoretical. It has real and immediate consequences.
One of the most significant risks is Legionella. These bacteria can grow in water systems where temperatures sit between 20°C and 45°C, and where water is allowed to stagnate. It can cause Legionnaires’ disease, a serious form of pneumonia.
In the UK, several hundred cases are reported each year. One such case led to the death of a 56-year-old man at a care home in Hampshire in 2020.
However, the risks are rarely caused by a single issue. In practice, they are typically driven by a combination of system design and how water is used across the building.
In one residential development, a review of the domestic water system found several issues within the distribution network. Some outlets were rarely used and needed regular flushing to keep water moving. There were also sections of dead-end pipework where water could sit for long periods, along with areas where water wasn’t consistently drawn through the system. Scaling and poor hygiene issues were also observed at a number of outlets. Together, these conditions allow water to become stagnant creating an environment where bacteria can develop if not properly managed.
In most cases, risk is not at the point of supply, but within the building system itself.
Heat network operators have a legal duty to assess and control these systems, and failure to do so can result in enforcement action, system shutdowns, and significant financial penalties.
More importantly, failures in drinking water systems can directly affect health, leaving very little margin for error.
How to manage drinking water quality in buildings
Managing drinking water quality requires a structured and consistent approach.
Proactive operators treat drinking or boosted cold water quality as a critical part of building management. They implement structured operation and monitoring plans, including:
- Routine water sampling and testing
- Regular inspection and cleaning of storage tanks
- Temperature monitoring and control
- Flushing regimes to prevent stagnation
- Clear record keeping of maintenance and corrective actions
All activities should align with regulatory requirements and industry best practice, with any system changes or upgrades carefully assessed for their impact on water quality. Even small changes in system design or usage can introduce new risks if not properly managed.
Regular reviews are essential to understand how systems are performing in practice and to identify where risks may be developing. Detailed mechanical surveys and Legionella risk assessments support this by providing a clear view of system conditions and areas that require attention.
Many operators choose to work with partners who can provide both technical insight and long-term system management, like our Maintenance services.
Because when it comes to drinking water, there is no margin for error.
