Application Cases

Wastewater Pump Station Pressure Monitoring over RS485

2026-10-18

A municipal wastewater operator needed discharge pressure from dispersed pump stations in one SCADA view. RS485 Modbus pressure transmitters on a single bus replaced gauge rounds and blind spots — including early warning of a rising main blockage.

A pump station that cannot be seen cannot be managed. Across a town's wastewater network, discharge pressure is the earliest indicator of blockages, worn impellers and failing non-return valves — yet at most unmanned stations it is read from a local gauge, on a weekly round, if at all. This anonymized case describes how one operator brought dispersed stations onto a single digital bus.

The situation

A municipal utility operates a network of sewage pumping stations feeding a treatment plant through rising mains of varying age. The stations have level control and run-time logging, but no pressure data reaches the control room: operators learn about a partially blocked main from high-level alarms — by which time the station is close to overflow — and about pump wear from energy bills months later.

The challenge

The stations are spread over several kilometres of industrial and residential areas, in wet, corrosive pits where electronics age fast. Pulling separate analogue loops per station back to a central point was uneconomical; the operator needed pressure at each station's discharge, trended centrally, with hardware that tolerates damp, vibration and the occasional pressure surge when pumps start against a full main.

The solution

Each station received a compact pressure transmitter with RS485 (Modbus RTU) output on the discharge line, ranged so normal duty sits mid-scale, with an overpressure rating covering pump-start surges. Stations were daisy-chained on shielded twisted pair to the plant's RTU/SCADA gateway — one bus, one address per station, pressure polled continuously alongside level. Transmitter housings and cable entries were specified for the pit environment (IP65+), and wetted parts in 316L stainless for the sewage-side condensate exposure.

The result

The control room now trends discharge pressure for every station. Within the first months, a slowly rising pressure trend at constant flow flagged a partially obstructed main weeks before it would have alarmed on level — it was jetted during a planned shift instead of an emergency callout. Pump wear is spotted the same way, as falling pressure at constant duty, and maintenance is scheduled from trend data rather than run hours alone.

Analogue loops would have delivered the same pressure values station by station; the bus delivered them as a network, at a fraction of the cabling cost — which is what made monitoring every station, rather than the two largest, affordable.

Products used: Industrial Pressure Transmitter · General Purpose Pressure Transmitter

Industry: Water & wastewater utilities