Microorganisms in water can form biofilms on equipment surfaces, reducing performance and causing operational problems. Control of microbial contamination is important in water systems such as RO membranes, cooling towers, heat exchangers, and drinking water pipelines.

While indicators such as TOC and BOD are widely used, direct microbial monitoring is important for quality assurance and preventive maintenance. However, heterotrophic plate count (HPC) methods typically require 5–21 days to obtain results.

This presentation introduces a rapid ATP-based method using a high-sensitivity luminometer and membrane filtration. Microbial ATP can be measured in approximately 5 minutes with sensitivity equivalent to 100 CFU/mL using 10 mL filtration. Results show good correlation with culture-based methods. The potential of this approach for early contamination detection and proactive water management will be discussed.