The flow of accountability: Understanding inflow and infiltration under RPS362

Measureable – Application Insights from Able Instruments

Sewer networks exceeding capacity during and after rainfall are often treated as a hydraulic problem first, yet without reliable measurement it can be difficult to determine where excess water is entering the system or how persistent that condition really is.

In wastewater systems, inflow and infiltration can increase flow well beyond normal dry weather conditions. Surface water inflow may cause rapid increases during rainfall events, while groundwater infiltration can sustain elevated flows long after rainfall has passed. Without clear evidence, operators may see the operational effect without fully understanding the source, scale, or persistence of the problem.

Flow measurement provides a practical basis for establishing normal network behaviour and identifying deviations across a catchment. By comparing dry weather baselines with wet weather and post-rainfall conditions, operators can begin to distinguish between short-duration inflow and longer-duration infiltration. Monitoring at multiple locations also helps narrow down where excess water is entering the network, supporting more targeted investigation and remediation activity.

Under regulatory frameworks such as the Environment Agency’s RPS 362, demonstrating control of these conditions increasingly depends on evidence rather than assumption. In that context, inflow and infiltration is not only an asset performance issue, but a matter of evidencing operational control.

Flow measurement allows operators to turn network behaviour into measurable evidence.

This application story forms part of our ‘Measureable’ series, which explores how measurement technologies help operators understand real-world process conditions, improve operational control, and support safer and more efficient industrial processes.

Read the full application story:

“The flow of accountability” Application Story (PDF)

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• Related Application Stories
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