Mains & building disinfection.

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What is mains and building disinfection?

Mains and building disinfection is the process of cleaning, flushing, and treating water systems to remove harmful bacteria, biofilm, and debris before they are brought into use. This process is essential for ensuring that both new and existing water systems provide clean, safe water that complies with BS8558 and PD855468 standards.

At Complii, we provide professional disinfection for mains water supplies, internal and external pipework, and building water systems. Our services are designed to eliminate microbiological contamination, maintain good water hygiene, and meet the strict requirements of local water authorities and the Legionella Control Association (LCA).

This service is particularly important for new installations, buildings with low usage, or properties that have been out of operation for extended periods.

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Why choose Complii?

How we can help.

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

Ensures safe, clean water before use

Flushing and disinfecting new or stagnant systems removes harmful pathogens, ensuring that clean, fresh water is available for use from day one.

Reduces the risk of Legionella and E. coli

Our process targets the bacteria most associated with health risks in stagnant or contaminated systems, including Legionella and E. coli, keeping your premises safe and compliant.

Complies with industry and legal standards

All disinfection work follows the guidance of BS8558, PD855468, and local water authority requirements, providing full assurance of compliance.

Restores water quality in underused systems

For buildings that have been mothballed or underused, disinfection clears stagnant water, removes biofilm, and restores system performance.

Prevents corrosion and blockages

Routine disinfection and flushing prevent the build-up of sediment and corrosion within pipework, helping maintain long-term water quality and flow efficiency.

Provides evidence through testing and certification

We conduct microbiological sampling before and after disinfection, with clear reporting that verifies the effectiveness of the process and demonstrates compliance.

Your questions answered.

We recommend professional cleaning and disinfection at least once a year, or whenever systems show signs of stagnation, contamination, or poor water quality.
Yes. Buildings that have been underused or closed, such as during the COVID-19 lockdowns, are at increased risk of Legionella and bacterial contamination. Disinfection should be carried out before reopening.
Flushing removes sediment and corrosion deposits that build up over time. Without this, blockages can form, affecting water quality and system performance.
Yes. You will receive full documentation including sampling results, confirmation of disinfection, and certification demonstrating compliance with BS8558 and PD855468.

News & insights

News / November 1, 2025

Introducing Complii: A new chapter in building safety and compliance

For years, navigating the world of building safety and regulatory compliance has felt complicated and fragmented. You might work with one specialist for your fire systems, another for water quality, and yet another for electrical testing. It's a system that creates administrative waste, unnecessary risk, and makes it hard to get a complete, clear picture of your building's health.

Insights / September 23, 2025

The benefits of thermographic imaging

Thermographic imaging is a powerful tool for identifying potential electrical faults before they become serious problems. By using specialist thermal cameras, engineers can detect heat patterns that indicate issues such as overloading, loose connections, or failing components.

For businesses, this proactive approach helps reduce risks, avoid costly downtime, and demonstrate compliance with electrical safety regulations.

News / September 23, 2025

PH Water and Air Technologies joins Complii

We are pleased to announce that PH Water and Air Technologies has joined Complii. This addition strengthens our water and air compliance services and further supports our mission to provide trusted, integrated compliance solutions across the built environment.

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Compliance with confidence.

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