Using Chlorination Effectively for Legionella Control and System Disinfection

Chlorination is a cornerstone of modern water treatment and plays a significant role in a comprehensive strategy for Legionella control. While temperature management is the primary preventative measure, Pipe Testing Services (PTS) expertly utilises chlorination and alternative disinfectants like chlorine dioxide for system remediation, disinfection following cleaning, and as a crucial component of Legionella risk management programs. This guide explores how PTS applies these chemical disinfection methods effectively and safely to mitigate Legionella risks.

The Role of Chemical Disinfection in a Legionella Control Strategy

Effective Legionella management, as outlined in guidelines like ACOP L8, requires a multi-barrier approach. While maintaining correct water temperatures is fundamental for preventing Legionella growth, chemical disinfection, primarily using chlorine or chlorine dioxide, becomes essential for:

System Remediation: Following a positive Legionella test or an outbreak, shock chlorination is often required to disinfect the entire water system. Learn more about our Legionella Remedial Works.
Post-Cleaning Disinfection: After physical cleaning of water systems (e.g., tanks, cooling towers) to remove scale and biofilm, chemical disinfection is necessary to eliminate remaining bacteria.
Commissioning New or Refurbished Systems: Ensuring new pipework or significantly altered systems are disinfected before use.
Secondary or Supplemental Control: In some complex or high-risk systems where temperature control alone is challenging, a carefully managed continuous low-level chemical residual can provide additional protection.

PTS conducts thorough Legionella Risk Assessments to determine the most appropriate control strategy for your specific system.

Applying Chlorine for Legionella Control: Methods and Considerations

While sometimes described as having limitations for ongoing Legionella control if not applied correctly (especially in systems with significant biofilm or temperature issues), chlorine remains a powerful and widely used disinfectant when expertly applied:

Shock Chlorination for Legionella Remediation

Shock chlorination involves introducing a high concentration of chlorine (e.g., 20-50 ppm) into the water system for a specific contact period. This is highly effective for:

Rapidly killing Legionella bacteria throughout a contaminated system.
Penetrating and helping to break down biofilms where Legionella can thrive.
Disinfecting systems after positive Legionella counts are identified through Legionella Testing Services.

Continuous Chlorination (Systemic Disinfection)

In certain circumstances, maintaining a continuous low-level chlorine residual (e.g., 0.5-1.0 ppm) can be part of an ongoing Legionella control strategy. This requires:

Careful monitoring of chlorine levels to ensure effectiveness without causing issues like corrosion or taste/odour complaints.
Consideration of factors like water temperature, pH, and system demand that affect chlorine efficacy.

Key Principles for Effective Chlorination against Legionella

To maximize the effectiveness of chlorination for Legionella control, PTS adheres to best practices:

Thorough System Assessment: Evaluating system design, characteristics, and potential Legionella risk factors.
Pre-Cleaning (where necessary): Reducing biofilm and sediment load enhances chlorine's ability to reach and kill bacteria.
Precise Chlorine Dosage & Contact Time: Calculated to overcome chlorine demand and achieve effective kill rates for Legionella.
Uniform Dispersion: Ensuring chlorinated water reaches all parts of the system, including dead legs and low-flow areas.
Vigilant Monitoring: Regular checks of chlorine levels during the process.
Thorough Documentation: Recording all aspects of the chlorination process for compliance.

Chlorine Dioxide: An Advanced Alternative for Legionella Control

While traditional chlorine is effective, chlorine dioxide (ClO₂) offers several advantages, particularly for complex Legionella challenges:

Superior Biofilm Penetration: ClO₂ is highly effective at penetrating and destroying biofilms, where Legionella bacteria often colonise.
Effectiveness Over a Wider pH Range: Unlike chlorine, ClO₂ maintains its disinfectant efficacy across a broader pH spectrum.
Lower Corrosion Potential: Often less corrosive to pipework than high concentrations of chlorine.
Effective at Lower Concentrations: Can achieve Legionella control at lower dose rates than traditional chlorine.

PTS may recommend chlorine dioxide for Legionella control in situations such as persistent biofilm problems, challenging water chemistry, or where ongoing chemical dosing is required in sensitive systems. We provide expert advice on the suitability of Chlorine Dioxide versus Chlorine for your specific Legionella control needs.

Safety and Compliance in Chemical Disinfection for Legionella

All chemical disinfection processes, whether using chlorine or chlorine dioxide, are conducted by PTS with the utmost regard for safety and regulatory compliance:

Understanding your responsibilities under ACOP L8 is crucial, and PTS ensures our services support your compliance efforts.

Integrate Chemical Disinfection
into Your Legionella Management Plan

Effective Legionella control often requires a combination of temperature management, system design, regular cleaning, and, where necessary, targeted chemical disinfection. Pipe Testing Services can help you determine the optimal role of chlorination or chlorine dioxide within your overall water safety plan.

Contact us to discuss how our expert Chlorination Services can be applied to manage Legionella risks in your water systems, or to learn more about our comprehensive Legionella Contractors services.

Phone: 01922 451646
Email: enquiries@pipetestingservices.co.uk
Address: Unit 27 Birchbrook Industrial Estate, Shenstone, Lichfield, Staffs, WS14 0DJ

Your water system’s safety and compliance are our top priorities. Connect with us now to embark on a journey toward pristine water quality.