Understanding Biofilm Formation and Control in Water Systems

Biofilms are complex microbial communities that form on surfaces in water systems, creating persistent contamination challenges that conventional disinfection methods often fail to address.

What is Biofilm?

A biofilm is a structured community of microorganisms enclosed in a self-produced matrix of extracellular polymeric substances (EPS). This protective matrix allows bacteria to attach to surfaces and shields them from environmental stresses, including chemical disinfectants.

Biofilms can form on virtually any surface in contact with water, including:

• Pipe walls and fittings
• Storage tanks and cisterns
• Cooling tower fill and drift eliminators
• Heat exchangers and condensers
• Shower heads and tap aerators

Why Biofilm Matters for Water Safety

Biofilms present several serious challenges for water system management:

• Pathogen harbour: Legionella, Pseudomonas, and other dangerous bacteria thrive within biofilm structures
• Disinfectant resistance: The EPS matrix reduces biocide penetration by up to 1000-fold
• Regrowth source: Even after treatment, surviving cells quickly re-establish populations
• Corrosion: Some biofilm-forming bacteria accelerate pipe degradation
• System efficiency: Biofilm accumulation reduces heat transfer and flow rates

Effective Biofilm Control Strategies

Successful biofilm management requires a multi-faceted approach:

• Prevention: Maintain consistent disinfectant residuals to prevent initial colonisation
• Penetration: Use biocides capable of penetrating the protective matrix
• Physical removal: Combine chemical treatment with flushing and cleaning
• Monitoring: Regular sampling to detect biofilm development early
• System design: Minimise dead legs and stagnant zones

Chlorine Dioxide: The Biofilm Solution

Chlorine dioxide is widely recognised as one of the most effective biocides for biofilm control. Unlike chlorine, which reacts rapidly with the outer layers of biofilm, chlorine dioxide's smaller molecular structure allows deeper penetration into the matrix.

ChloroKlean Plus L20's regenerative chlorine dioxide technology provides sustained release of active ClO₂, maintaining effective concentrations over extended periods to fully penetrate and eliminate established biofilms.