The Power of Real-time Chlorine Monitoring - Ozwater 2025 Presentation
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A peer-reviewed study presented at OzWater 2025 — the Australian Water Association's premier national conference — has confirmed what TracWater has long demonstrated in the field: that real-time, continuous water quality monitoring reveals critical information about drinking water safety that traditional grab sampling simply cannot provide.
The study, conducted in collaboration with Yarra Valley Water (YVW), used TracWater portable online sensors to monitor free chlorine residual (FCR) patterns across a complex unfiltered drinking water distribution zone in Melbourne.
Key Findings
Peak free chlorine at network dead ends occurred outside the 7am–2pm window when routine laboratory samples are collected — meaning compliance monitoring may systematically miss peak vulnerability periods.
TracWater sensors achieved R²=0.83 correlation with maintenance contractor field samples and R²=0.70 with NATA-accredited laboratory results across 15 months of continuous monitoring.
Pipe cleanliness had significantly less impact on chlorine levels than water age and nutrient load from unfiltered supply — a counterintuitive and important finding for regulators setting universal performance targets.
Even ice-pigging — one of the most effective pipe cleaning methods — only improved chlorine levels for three days before returning to pre-cleaning levels.
The findings have direct regulatory relevance: as Victorian water quality regulations strengthened in July 2025. Continuous monitoring data is now essential to setting evidence-based, network-specific chlorine performance targets.
Read the full paper: 'Using Portable Online Sensors to Assess Chlorine Performance in an Unfiltered Drinking Water Supply System' — Haruwarta, Jayaratne, McCormick, O'Brien & McKelvey, OzWater 2025.
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