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What Is Pre‑Commission Cleaning?
Pre‑commission cleaning is the process of flushing and chemically treating closed circuit water systems — such as heating, chilled water, and condenser loops — before they are brought into operation. During installation, new pipework often accumulates debris including mill scale, jointing compounds, corrosion residues, and biological contaminants. If left untreated, these can cause serious issues once the system is live.
At London’s H2O, our pre‑commission cleaning service is designed to remove this contamination, improve flow, protect critical components, and prepare the system for reliable, long-term performance. By following industry-recognised guidance such as BSRIA BG29/2021 and BS8552, we help ensure that every system we clean meets the expectations of consultants, contractors, and building owners alike.
It is especially important on projects where system performance is contractually guaranteed or where warranties depend on proving cleanliness and inhibitor protection.
Pre‑commission cleaning should be carried out:
When installing new closed loop systems
When refurbishing or modifying existing pipework
After system stagnation or contamination
Before client handover and commissioning
Without proper cleaning, new systems are at risk of poor performance, early failure, and non-compliance with industry standards. Debris and biofilm can lead to blockages, reduced heat transfer, corrosion, pump damage, and long-term efficiency losses.
More importantly, modern systems often operate at lower flow rates with advanced controls and tight tolerances — meaning even minor contamination can have a major impact. Pre‑commission cleaning is not just good practice; it’s essential for warranty protection, system longevity, and client handover requirements.
Choosing London’s H2O ensures your project starts on the right foot, avoiding costly remedial work and giving building owners full confidence in their new plant.
Every clean begins with a detailed system review. Our engineers assess the layout, confirm flushing points, and check that backflow protection and drainage arrangements are in place. We then carry out flushing using static and dynamic methods, ensuring high-velocity flow through all parts of the system to dislodge particles and biofilm.
Once flushing is complete, we introduce specialist chemicals such as degreasers, scale removers, and biocides. These are carefully selected to match the system material, temperature, and water quality. After treatment, the system is thoroughly rinsed to remove all chemical residues.
As a final step, we dose the system with corrosion inhibitors and/or biocides to prevent future fouling, then collect samples for laboratory analysis. Clients receive full documentation, including test results, system volume calculations, flow data, and a BSRIA-compliant certificate of cleanliness.
London H2O provides expert water treatment solutions for homes and businesses across London. We deliver clean, safe, and efficient systems with a focus on quality, sustainability, and service.
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