How better visibility in rising sewer mains can help utilities reduce pollution incidents, prevent costly damage and meet regulatory goals
Across the UK and the world, utilities are under increasing pressure to improve the reliability and efficiency of their wastewater networks. Rising sewer mains, the pipelines that transport sewage under pressure from pump stations to treatment plants, are a critical but often overlooked part of this system. Buried below the surface, these mains face a range of challenges, from pressure transients and aging infrastructure to limited monitoring access (see Figure 1), making it difficult to spot issues before they escalate.
Despite carrying large volumes of effluent every day, these mains typically operate without real-time visibility of what’s happening inside them.
This lack of operational insight means leaks, bursts and pressure events can go unnoticed until they cause significant environmental or reputational damage. Better leak detection offers a way to change that by providing the data and early warnings utilities need to protect assets, reduce pollution incidents and meet future regulatory commitments. In this blog, Atmos International’s (Atmos) Technical Director Phil Edwards covers:
- Why rising sewer mains are particularly vulnerable to hidden leaks
- Understanding the behavior of rising mains
- Why multi-method analysis is essential
- Real-world performance
- The future of rising main monitoring
A hidden problem beneath the surface: why are rising sewer mains particularly vulnerable to hidden leaks?
Figure 1: Rising sewer mains run below ground and face challenges such as pressure transients, aging infrastructure, and limited monitoring access, making leaks difficult to detect before they cause damage
Unlike gravity sewers, rising mains work under pressure, which means failures occur more frequently and are harder to fix. In many networks, operators have limited data at their disposal to identify issues. While useful, these systems aren’t designed for fine-scale leak detection, especially when it comes to slow leaks, air ingress or pressure transients.
When a small leak develops, it might only cause a gradual pressure loss during idle conditions, or a subtle vibration change when pumps running. These small shifts are easy to miss with traditional low-frequency data. By the time the issue becomes visible at the surface, thousands of liters of wastewater may have escaped.
Without a continuous view of pressure behavior, utilities face increased maintenance costs, greater risk of pollution events, and even premature pipe failure due to repeated pressure surges.
Understanding the behavior of rising mains
Rising mains experience two distinct operational states: idle and running. Each of these can reveal different leak signatures, so recognizing how these conditions affect pressure and flow is key to detecting leaks quickly and accurately.
Atmos has field experience with all these pipeline conditions:
Idle conditions (when pumps are off)
This allows for analysis of how quickly pressure decays. A faster-than-normal drop often signals an active leak (see Figure 2).
Figure 2: Idle condition analysis shows faster-than-normal pressure decay, indicating a possible active leak when pumps are off
Running conditions
This reveals low-pressure anomalies that indicate large or newly developed leaks (see Figure 3).
Figure 3: Low-pressure anomalies during running conditions help identify large or newly developed leaks in rising mains
Detecting leaks across these states requires high-frequency data (typically 60 Hz) far beyond the resolution of conventional telemetry (see Figure 4).
Figure 4: Continuous 60 Hz data provides the resolution needed to detect subtle leak signatures that conventional telemetry can miss
Why multi-method analysis is essential
No single technique can detect every type of leak. That’s why Atmos applies a multi-method analysis approach, combining several proven techniques to identify and locate leaks under all operating conditions.
These methods include:
- Negative pressure wave detection to capture sudden bursts or ruptures (see Figure 5) and provide a location estimate
- Rate of idle pressure drop analysis to highlight small or slow leaks
- Low running pressure monitoring to flag pressure loss during operation
- Single-ended leak location using only inlet data, ideal for sites where access to both ends of a main isn’t practical
Figure 5: Transient monitoring with high resolution negative pressure wave data
By integrating these methods, operators gain a complete picture of their rising mains, from subtle seepage to catastrophic failure, and can act before incidents escalate.
Supporting regulatory performance and sustainability goals
From 2025 onwards, Ofwat’s AMP8 performance commitments have emphasized reducing pollution incidents and improving asset reliability. Fast and accurate leak detection directly supports these goals by helping utilities:
- Detect and isolate leaks before they reach the surface
- Prevent environmental contamination and reputational harm
- Reduce pumping inefficiencies
- Extend the lifespan of critical infrastructure
Investing in continuous monitoring technology isn’t just a matter of compliance, it’s a proactive step toward environmental protection and operational resilience.
Real-world performance
Recent deployments of Atmos systems in wastewater networks have shown how continuous, high-resolution monitoring can improve both leak detection speed and operational decision-making on rising mains.
In one installation, an Atmos Sentinel system identified a leaking non-return valve during shut-in conditions by confirming a faster-than-normal pressure decay. This issue had not been visible through conventional monitoring.
Once resolved, the utility reported improved pumping efficiency and more stable system operation, demonstrating how early detection can reduce energy waste and unnecessary wear on assets.
In another case, continuous monitoring by Atmos hardware detected a leak event within 13 minutes of it occurring. The same event was only identified by existing utility methods more than 10 hours later. This delay highlights the limitations of low-frequency telemetry on rising mains and the value of continuous insight. Earlier detection allowed the operator to respond sooner, helping to reduce the risk of escalation, environmental impact, and repair costs.
Together, these examples show how real-time visibility enables utilities to move from reactive investigation to proactive intervention, particularly on assets that are otherwise difficult to monitor.
The future of rising main monitoring
As wastewater systems face tighter regulation and aging infrastructure, real-time visibility is becoming essential. Rising sewer mains remain vulnerable assets and the cost of poor insight, in environmental, operational and reputational terms, is too high to ignore.
Modern leak detection technology is helping utilities move from reactive maintenance to proactive prevention. With high-frequency data, multi-method analysis and reliable hardware, Atmos International’s solutions give operators the visibility they need to protect assets, manage pressure events and meet future performance commitments with confidence.
Go from reactive maintenance to proactive prevention