Sewage Flow Monitoring

Open Channel Flow Meter Technology

Since 1987, Environmental Technical Services (ETS) has managed a number of open channel flow meters. These devices are used to measure flows of sewage in closed pipes, or storm water in ditches and streams.

Monitoring of flows in sanitary and combined sewer systems allows for an understanding and quantification of the components of the flow itself. It is also desirable to determine the volume of extraneous flow in the system. Extraneous flows occur in the form of relatively clean rain water or ground water that enters the sewer. The influx of this water robs the sewer lines of precious capacity. The treatment plant is also overloaded by sudden inflows of relatively clean rain water. This overloading can cause problems with the sensitive biochemistry of the treatment plant and can also cause hydraulic problems within the plant.

The quantification of flows can lead to the identification of the sources of these extraneous flows. Once identified, programs to eliminate the inflow sources can be derived.

Flow monitoring in ditches or natural streams can be used to understand how storm water behaves in these systems. In the natural stream, flow monitoring data can be used to determine not only its physical stability but the ecological viability it offers. This can be of enormous value when undertaking restoration or rehabilitation of the creek or stream.


Portable open channel flow meter installed in a sanitary sewer in the Town of Fort Erie. This particular meter uses a magnetic field to determine the liquid velocity, and a pressure sensor to determine fluid depth. The white canister in front of the open manhole houses the data logger and power supply, and is usually hung from a ladder rung. The sensor is mounted in the sanitary sewer at the bottom of the manhole.


Leads connecting two flow monitors to sensors mounted in two pipes influent to a manhole.

ETS offers a full range of flow monitoring services to both the public and private sectors. For more information about this service, please contact Kyle Moate.

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