Pre-commission cleaning services

Our services

What is pre-commission cleaning?

Pre-commission cleaning is the process of flushing and chemically cleaning newly installed closed systems, such as LTHW, CHW, MTHW, HTHW, and condenser water circuits, before they are brought into operation. The aim is to remove construction debris, installation residues, and soluble contaminants to ensure that the water quality within the system meets BSRIA BG29:2021 standards prior to commissioning.

At Complii, our engineers are fully trained and certified in accordance with BSRIA BG29:2021 (Pre-commission Cleaning of Pipework Systems). We ensure every new system is professionally cleaned, tested, and documented before handover, providing a clean and balanced foundation for long-term system performance.

Why choose Complii?

How we can help.

Protect your people, property, and business. Here’s why we’re the right choice for pre-commission cleaning.

Ensures system efficiency from day one

Removing debris, flux residues, and particulate matter prevents blockages in control valves, fan coil units, and heat exchangers, ensuring optimal flow and system balance.

Prevents long-term corrosion and fouling

By chemically treating the system and flushing out contaminants, pre-commission cleaning minimises corrosion and biofouling risk, protecting valuable assets such as boilers and chillers.

Compliant with BSRIA BG29:2021 standards

All works are conducted in accordance with BSRIA BG29:2021 and BS 8552, ensuring compliance with recognised best practice for new system installation and handover.

Reduces microbiological risk

Pre-commission cleaning removes the debris and stagnation conditions that encourage bacterial growth, including Pseudomonas, Sulphate Reducing Bacteria (SRB), and Nitrite Reducing Bacteria (NRB).

Provides verified water quality results

Independent laboratory analysis confirms that iron, solids, and pH levels meet BSRIA benchmarks. We supply all test certificates and water sample reports at handover.

Protects long-term performance and warranty

Systems that begin life clean and chemically balanced are less likely to develop corrosion or efficiency issues, supporting warranty conditions and lowering future maintenance costs.

Your questions answered.

During installation, pipework and equipment accumulate debris such as swarf, flux, and grease. If left untreated, this material can obstruct valves, reduce flow rates, and damage equipment. Pre-commission cleaning removes these contaminants to ensure safe, efficient operation.
Pre-commission cleaning is carried out to BSRIA BG29:2021, which outlines cleaning methods, chemical treatment procedures, and post-clean verification testing for new systems.
Samples are analysed for iron, pH, suspended solids, and bacterial counts (including Pseudomonas and TVC). The results are compared against BSRIA limits to confirm cleanliness and inhibitor performance.
It should be completed before final balancing and handover, while all valves can still be fully opened to allow maximum flushing flow through the system.
Yes. Existing or contaminated systems can be chemically cleaned and re-inhibited to restore performance, following modified procedures from BSRIA BG50:2021.
You’ll receive a full cleaning certificate, laboratory reports, water test results, and photographic evidence confirming compliance and cleanliness at handover.

Pre-commission cleaning.

What is pre-commission cleaning?

How we can help.

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