Cold Water Storage Tank Cleaning & Disinfection
Cold water storage tanks accumulate sediment, biofilm and biological contamination over time. Our cleans cover physical inspection, sediment removal, surface scrubbing, chlorination disinfection at the appropriate concentration and contact time, full flush-through and post-clean verification sampling.
Frequency
Typically annual (risk-led)
Site time
Half to full day per tank
Deliverable
Disinfection record + photo report
Why it matters
Cold water storage cisterns are one of the highest-risk assets in a building's water system. Sediment harbours bacteria, biofilm protects them from disinfectants, and any breach of tank integrity (loose lid, missing insect screen, sunlight ingress) accelerates the problem.
Annual visual inspection is the sensible baseline, with cleaning and disinfection triggered by condition. Done properly, a clean restores the tank to a known-good baseline; done badly, it just stirs up the contamination.
Who it's for
- Buildings with cold water storage cisterns of any size
- Care homes and healthcare buildings (typically annual cycle)
- Sites where tank inspection has identified sediment, scale or biofilm
- Following remedial pipework or tank installation
- Where Legionella sample results require disinfection
What's included
- Pre-clean tank inspection and condition report
- Drain-down and physical sediment removal
- Surface scrub of tank base and walls
- Chlorination to required concentration and contact time
- Refill, flush-through and outlet verification
- Post-clean Legionella verification sampling on request
What you receive
- Written disinfection record
- Photographic before/after report
- Verification sample results (where commissioned)
- Recommendations for ongoing tank inspection regime
Our process
A repeatable, engineer-led delivery sequence.
- 1
Pre-clean inspection
We inspect the tank, photograph its condition and confirm the disinfection method, isolation and bypass arrangements.
- 2
Isolation & drain-down
Cold water supply is isolated, the tank is drained and remaining sediment is removed manually.
- 3
Physical clean
Tank base, walls and lid are scrubbed; debris is bagged and removed from site.
- 4
Chlorination
The tank is refilled and dosed to 50 ppm free chlorine for one hour (or to specification), with all outlets opened and flushed through.
- 5
Neutralise & refill
The system is neutralised, fully drained and refilled with potable water; chlorine residual is tested at outlets to confirm restoration.
- 6
Verification sampling
Where commissioned, post-clean Legionella samples are taken to confirm the disinfection was effective.
Frequently asked questions
Related services
Legionella Risk Assessments
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Water Sampling & Laboratory Testing
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Mechanical & Plumbing Remedial Works
Learn moreSee which sectors we serve for guidance specific to your building type.
Want background reading? Browse our compliance guides or talk to an engineer.
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