Chlorine Dioxide for Building Water System Disinfection and Commissioning

Why the Water Industry is Re-evaluating Traditional Chlorination

Across the UK, thousands of new buildings, hotels, holiday parks, care homes, healthcare facilities and commercial premises undergo water system disinfection every year.

Traditionally, this has been achieved using sodium hypochlorite or other chlorine-based disinfectants. While these methods remain widely used, increasing attention is being given to chlorine dioxide due to its ability to penetrate biofilm, maintain effectiveness across a broad pH range and provide highly effective microbiological control.

For building owners, water hygiene consultants and commissioning contractors, the question is no longer whether chlorine dioxide works, but whether it can provide operational advantages over traditional chlorination methods.

Understanding the Regulatory Framework

Within the UK there are two distinct areas of responsibility.

Public Water Supply

The public water supply network from the treatment works to the customer meter is regulated by the Drinking Water Inspectorate (DWI) and local water undertakers.

Building Water Systems

Once water enters a building, responsibility transfers to the building owner or duty holder.

This includes:

• Incoming cold-water services
• Cold-water storage tanks
• Pipework distribution systems
• Hot water systems
• Outlets and terminal fittings

Management of these systems is typically guided by:

• ACOP L8
• HSG274 Part 2
• BS8558
• Water Hygiene Industry Best Practice

The primary objective is simple:

Maintain microbiologically safe water and minimise Legionella risk.

The Hidden Challenge: Biofilm

Most water hygiene issues originate from biofilm.

Biofilm provides protection for:

• Legionella bacteria
• Pseudomonas aeruginosa
• E.coli
• General bacterial contamination

Traditional chlorination can be highly effective against free-floating bacteria but may struggle to penetrate established biofilm layers.

This is one reason why chlorine dioxide has attracted increasing interest.

Unlike free chlorine, chlorine dioxide can penetrate and disrupt biofilm structures while simultaneously delivering powerful disinfection performance.

Why Chlorine Dioxide is Different

Chlorine dioxide operates through selective oxidation.

Unlike chlorine:

• It does not hydrolyse significantly in water.
• It remains effective across a broad pH range.
• It produces fewer chlorinated organic by-products.
• It exhibits excellent biofilm penetration.
• It maintains strong activity against Legionella and Pseudomonas.

These characteristics have led to widespread adoption in:

• Healthcare facilities
• Hospitals
• Care homes
• Food processing facilities
• Potable water systems
• Industrial water treatment

ChloroKlean vs Traditional Chemistries

Typical Commissioning and Disinfection Targets

Traditional chlorination procedures commonly target:

The objective is to achieve microbiological control throughout the entire system.

Example ChloroKlean Dosing Table

Assuming ChloroKlean is dosed at approximately:

20 ml per 1,000 litres = 0.5 ppm chlorine dioxide

The following guide illustrates approximate chlorine dioxide concentrations.

Dosing Guide Per 1,000 Litres

Actual residual concentrations should always be confirmed using appropriate testing methods.

Potential Operational Advantages

For water hygiene contractors, chlorine dioxide may offer several practical advantages:

Improved Biofilm Removal

Chlorine dioxide can penetrate and disrupt established biofilm, helping expose microorganisms that may otherwise remain protected.

Reduced Chemical Demand

Because chlorine dioxide targets microorganisms differently from chlorine, lower concentrations may achieve comparable microbiological outcomes in some applications.

Broad pH Performance

Chlorine dioxide maintains effectiveness across a wider pH range than traditional free chlorine systems.

Lower Taste and Odour Impact

Many facilities report reduced chlorinous odours compared with traditional chlorination.

Enhanced Legionella Control

Chlorine dioxide has an established reputation within water hygiene sectors for controlling Legionella within building water systems.

Suitable Applications

ChloroKlean may be considered for:

• New building commissioning
• Cold water storage tank disinfection
• Pipework disinfection
• Legionella remediation
• Healthcare water systems
• Hotel water systems
• Holiday park water systems
• Care homes
• Educational facilities
• Commercial premises

The Future of Building Water Disinfection

As water hygiene professionals increasingly focus on biofilm management rather than simple residual disinfection, chlorine dioxide continues to gain recognition as a highly effective tool within building water systems.

While traditional chlorination remains widely used, many operators are now evaluating chlorine dioxide-based approaches where enhanced biofilm control, Legionella management and system hygiene are critical.

ChloroKlean provides a practical chlorine dioxide solution designed to support modern water hygiene programmes and help building operators maintain cleaner, safer water systems.