How Often Should Water Tanks Be Cleaned?
Water storage tanks are a critical part of many commercial buildings, supplying water for drinking, washing, heating systems and operational processes. When these tanks are not properly maintained, they can quickly become a health risk and a compliance concern. For facility managers and duty holders, understanding how often water tanks should be cleaned is essential to protecting building users and meeting legal responsibilities.
Why Water Tank Cleaning Matters
Over time, water tanks naturally accumulate sediment, scale, rust and organic debris. These deposits can encourage the growth of harmful bacteria, including legionella, particularly in systems where water stagnates or temperatures are poorly controlled. Poor water quality can lead to unpleasant odours, discolouration and, in serious cases, illness.
Regular cleaning not only improves water quality but also helps extend the life of the tank and associated pipework, reducing the risk of corrosion, blockages and costly emergency repairs.
How Often Should Water Tanks Be Cleaned?
As a general rule, commercial water tanks should be inspected and cleaned at least once every 12 months. This annual clean is widely regarded as best practice and is suitable for many office buildings, warehouses and standard commercial premises.
However, some buildings will require more frequent cleaning, such as:
● Healthcare facilities, care homes and schools
● Buildings with high water demand or vulnerable occupants
● Older systems or tanks showing signs of corrosion
● Properties that experience low occupancy or intermittent use
In higher-risk environments, cleaning may be recommended every six months, depending on the findings of a legionella risk assessment.
What Do the Regulations Require?
UK legislation, including the Health and Safety at Work Act and the HSE Approved Code of Practice L8, requires duty holders to manage and control the risk of legionella in water systems. While the regulations do not specify exact cleaning intervals, they do require that water tanks are maintained in a clean condition and monitored as part of an ongoing risk management programme.
A professional legionella risk assessment will identify the appropriate inspection and cleaning frequency for each system. Following these recommendations is key to demonstrating compliance and due diligence.
Signs Your Water Tank Needs Cleaning
Even if your next scheduled clean is months away, certain warning signs indicate that action may be needed sooner. These include discoloured water, unusual smells, visible sediment inside the tank, or failed water quality test results. Any of these issues should be investigated promptly to prevent further deterioration.
What Does Professional Cleaning Involve?
Professional water tank cleaning typically includes draining and isolating the tank, removing debris and sediment, mechanically cleaning internal surfaces, and disinfecting the tank in line with HSE guidance. Once complete, the tank is refilled and checked, with detailed reports provided for compliance records.
Key Takeaways for Facility Managers
There is no single cleaning schedule that suits every building, but for most commercial properties, annual water tank cleaning is the minimum standard. A risk-based approach, supported by professional assessments and regular maintenance, is the most effective way to keep water systems safe, compliant and reliable.
Proactive water tank cleaning protects occupants, reduces risk and gives facility managers peace of mind that their water systems are being properly managed.
