Cold Water Storage Tank Cleaning & Chlorination
Cold water storage tanks (CWST) must be regularly inspected, cleaned and disinfected to control sediment, biofilm and Legionella risk. At National Hygiene Serviced Ltd, we provide professional CWST cleaning, chlorination, temperature monitoring and remedial works using trained engineers, calibrated equipment and UKAS-accredited water analysis to maintain safe, compliant water storage systems.
What Are Cold Water Storage Tanks (CWST)?
Cold water storage tanks supply water to sinks, wash hand basins, showers, toilets and other outlets across a wide range of buildings. Because stored water can stagnate and warm over time, these systems require regular inspection, cleaning and disinfection to remain safe.
Important: During warmer summer months, cold water temperatures can rise above the recommended maximum of 20°C, increasing the risk of bacterial growth. Additional monitoring and checks may be required during these periods.
Why CWST Cleaning & Chlorination Is Essential
Without routine maintenance, cold water storage tanks can accumulate:
- Sludge and sediment
- Scale deposits
- Biofilm build-up
These conditions create an ideal environment for Legionella bacteria to grow. Biofilm and scale can also shield bacteria from disinfectants, making effective cleaning and chlorination critical for water safety.
Annual cleaning and disinfection, or more frequently as dictated by risk, is a key control measure within water safety management plans.
Our operatives are not only fully trained in water tank cleaning and tank chlorination, but also in ensuring the safety of everyone whilst cleaning is carried out. All engineers carry the CSCS passport to safety and are all enhanced DBS checked to ensure confidence when working on site and in areas with vulnerable people
Our cold water storage tank cleaning & chlorination maintenance service includes:
Why Choose Us?
Our collaborative and proactive approach drives efficiency, cost savings and offers our clients peace of mind. We are committed to continuous improvement, through innovation and investment in our personnel, methodologies and equipment.
We offer extremely competitive rates and daytime, evenings or weekends to offer minimal disturbance to our customers.
FAQ’s
How often should cold water storage tanks be cleaned?
Cold water storage tanks should be cleaned and disinfected at least annually, or more frequently if risk assessments or monitoring results indicate increased risk.
Why is chlorination of CWST important?
Chlorination removes bacteria, including Legionella, and disinfects internal surfaces to reduce the risk of contamination.
What temperature should cold water be stored at?
Cold water should be stored and distributed below 20°C. During summer months, temperatures can rise, requiring additional monitoring and control measures.
Do CWSTs need to be sampled and tested?
Yes. Sampling of incoming mains and stored water helps verify water quality and confirms that control measures are effective.
Is Legionella risk linked to dirty water tanks?
Yes. Sludge, sediment, scale and biofilm provide favourable conditions for Legionella growth if tanks are not properly maintained.
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