The Non-Revenue Water Problem
Non-revenue water (NRW) is water that a utility produces, treats, pumps, and distributes — but never sells. The American Water Works Association (AWWA) reports that the US average NRW rate is approximately 16% of water produced. For a utility producing 10 million gallons per day, that’s 1.6 million gallons per day of water that costs money to treat and pump but generates no revenue.
NRW has three components:
- Real losses: Physical losses from pipe leaks, main breaks, and reservoir overflow — water that actually leaves the system
- Apparent losses: Water that was used but not billed — meter error, unauthorized connections, billing data errors
- Unbilled authorized consumption: Fire hydrant flushing, main cleaning, fire department use — legitimate use that isn’t billed
For most utilities, real losses are the largest component. And most real losses come from leaks that develop gradually and go undetected until they fail completely or until an annual audit reveals elevated NRW.
ArgusIQ addresses this with continuous pipe network monitoring that surfaces developing leak patterns before they become visible failures or significant loss events.
The Digital Twin of the Pipe Network
A pipe network digital twin in ArgusIQ is not a CAD model of the pipes. It’s a structured operational record of the network’s pressure and flow behavior — one that establishes what normal looks like for each monitoring point and alerts when conditions deviate from normal.
Pressure Monitoring: The Foundation
Pressure is the primary indicator of pipe network health. Pressure that’s lower than expected at a point in the network can indicate a leak between the upstream source and the monitoring point. Pressure that’s higher than expected at night (when consumption is minimal) confirms there’s no major leak — low-consumption periods are the baseline.
ArgusIQ IoT Hub connects to pressure loggers deployed at:
- District meter area (DMA) inlet boundaries
- Strategic points within distribution zones
- Pump station discharge and suction headers
- Storage tank inlet/outlet headers
LoRaWAN pressure loggers at 15-minute reporting intervals provide the continuous pressure record that periodic manual reads cannot. The IoT SimpleLink gateway at the water tower, pump station, or utility building provides the network connectivity for the DMA sensor network.
Each monitoring point has an Asset Hub record: location (mapped to the pipe network in Space Hub), installation date, calibration record, and the baseline pressure profile for that point (what normal pressure looks like at 2 AM, at peak demand, at various times of day and week).
Night Flow Analysis: Early Leak Detection
The most reliable leak detection method available from pressure and flow data is minimum night flow analysis. Between 2 AM and 4 AM, water demand in most distribution zones is minimal — primarily leakage and a small amount of legitimate use from overnight commercial activity.
The expected minimum night flow for a DMA can be estimated from the number of service connections and the zone’s historical minimum consumption. When actual night flow (measured at the DMA inlet) significantly exceeds expected minimum flow, the excess is likely real loss — leakage.
ArgusIQ Alarm Engine runs the night flow analysis automatically:
- For each DMA, the system records the 2 AM – 4 AM flow measurement nightly
- The actual minimum night flow is compared against the DMA’s rolling baseline minimum (30-day average of minimum night flows)
- When minimum night flow exceeds the baseline by more than the configured threshold (typically 10–15%), an alert fires to the distribution operations team
- The alert includes the flow excess estimate and the time series of recent minimum night flows — showing whether this is a new issue or a gradually worsening trend
A DMA whose minimum night flow has been slowly rising for three weeks is showing the signature of a developing leak. Identifying it at week 3, before the leak has grown to street-level visibility, enables a proactive investigation at a fraction of the eventual repair cost.
Pressure Transient Detection
Pressure transients — rapid pressure spikes or drops caused by pump starts, valve operations, or water hammer — are both an indicator of system events and a potential cause of main breaks. High-frequency pressure monitoring (logging at 1-minute or shorter intervals) detects transients that 15-minute interval logging misses.
ArgusIQ Asset Hub stores the pressure time series at full resolution. When a transient event occurs, the pressure record shows the event’s magnitude, duration, and timing. Repeated transient events from the same source — a pump that’s water-hammering on start — create a pattern that correlates with eventual pipe failure risk.
The maintenance history record in ArgusIQ CMMS links main break events to the pressure history for the affected zone — building the historical record that eventually supports correlating pressure patterns with break risk.
From Anomaly Detection to Leak Localization
Detecting that a DMA has excess night flow is the first step. Localizing the leak within the DMA to enable repair is the second step — and it requires different tools.
Acoustic Leak Correlation
Acoustic leak correlators detect the sound that escaping water makes as it exits a leaking pipe. Two correlators placed at access points (fire hydrants, valve boxes) on either side of the suspected leak segment detect the sound; the timing difference between the two measurements localizes the leak to a specific segment of pipe.
ArgusIQ Asset Hub records acoustic correlation survey events as inspection work orders: survey date, correlator placement points, correlation result (distance from each end), and the recommended excavation point. The record creates the documentation for the excavation and repair sequence.
Step Testing
For DMAs where a single leak is suspected, step testing — systematically closing valves to isolate sub-zones and measure how minimum night flow changes — can localize the leak to a pipe segment.
ArgusIQ CMMS manages the step test procedure as a structured work order: which valves to close, in which sequence, what flow measurements to record at each step. The results feed back into the Asset Hub record, updating the DMA’s leak status.
Asset Management for Water Infrastructure
Pipe and Asset Records
ArgusIQ Asset Hub maintains records for the physical assets in the water distribution system: mains, service connections, hydrants, valves, pump stations, storage tanks, and treatment facilities.
Pipe records include: material (cast iron, ductile iron, PVC, HDPE, asbestos cement), diameter, installation year, lining status, and known condition from inspections. Older cast iron mains are inherently higher risk than newer ductile iron; the material and age data enables risk-based prioritization of main replacement programs.
When a main break occurs, the break event is recorded in the CMMS work order with the pipe record reference — so the history of breaks on specific pipe segments accumulates over time. A 1950s cast iron main that has broken three times in five years tells a different story than one that has broken once in thirty years.
Pump Station Monitoring
Pump stations are the critical infrastructure that moves water through the distribution system. Pump failures interrupt service and can require emergency response at any hour.
ArgusIQ IoT Hub connects to pump station SCADA or direct sensor interfaces — pump motor current, discharge pressure, suction pressure, VFD status, runtime hours. Asset Hub health scoring for pump stations aggregates these readings against the station’s operational baseline.
PM schedules in CMMS track operating hours for pump maintenance — bearing lubrication, impeller inspection, seal replacement — tied to the actual runtime data rather than calendar intervals.
Regulatory Reporting and Compliance
Water utilities operate under EPA Safe Drinking Water Act requirements and state regulatory programs that mandate water quality monitoring, infrastructure reporting, and — in some states — NRW accountability reporting.
ArgusIQ generates the structured reports regulators require:
- Annual water audit: AWWA water audit format reconciliation — production, authorized consumption, apparent losses, real losses, calculated NRW
- Pressure maintenance compliance: Documentation of system pressure compliance with regulatory minimums at monitoring points
- Water quality exceedances: Automatic alert and record when water quality parameters (chlorine residual, turbidity) exceed regulatory limits — with the structured event record that state reporting requires
Ask Argus for Water Operations
Natural language queries give water operations teams fast access to the network monitoring record:
“Which DMAs have had minimum night flow above baseline for more than 5 consecutive nights?”
“What was the pressure at Station 4 during the main break event on January 12th?”
“Show me all main breaks in the past 3 years on pipes installed before 1970.”
“Which pump stations have operating hours approaching PM service intervals?”
“What is our current estimated NRW rate based on the past 30 days of data?”
The answers support the operational decisions water managers make daily — without requiring a GIS specialist or data analyst to pull the relevant records.
Talk to our team about ArgusIQ for your water distribution system.