Why Manholes Are the Weakest Point in Sewer Networks
In sewer networks, attention is often focused on main pipelines. However, the most critical failures do not always originate where we expect. In many cases, manholes represent the weakest point in the network.
Subject to multiple stresses and often overlooked in inspection strategies, they are responsible for a large share of structural issues, including infiltration and exfiltration. Understanding their vulnerability is essential to improving infrastructure management and preventing costly deterioration.
Structures at the Core of the Network… Yet Highly Exposed
Manholes play a central role in sewer networks. They provide access, connect pipelines, and facilitate maintenance and inspection operations. However, this very function also makes them particularly vulnerable. Unlike pipes that are uniformly buried, manholes are exposed to both underground stresses (soil pressure, groundwater) and surface stresses (traffic loads, dynamic forces). They also concentrate multiple connections, increasing the number of potential failure points.
A Concentration of Structural Defects
Manholes are often the location of numerous structural defects. Common issues include:
- cracks in the walls
- deteriorated or open joints
- benching deterioration
- infiltration at the frame and cover
- signs of advanced corrosion
This concentration of defects is due to both the complexity of their structure and their direct exposure to external conditions.
A Key Role in Infiltration
Manholes are one of the primary sources of infiltration in sewer networks. Because of their multiple entry points and exposure to the surrounding environment, they allow external water to enter the system easily. In some cases, they can account for a significant portion of inflow, contributing to hydraulic overload, increased treatment costs, and reduced overall system performance.
A Critical Point for Exfiltration
Conversely, manholes can also be major leakage points. When their structure is compromised, they allow wastewater to escape into the surrounding soil, with direct consequences for the environment and public health. These leaks often go unnoticed without proper inspection, increasing long-term risks.
Why Manholes Are Often Under-Inspected
Despite their importance, manholes are often inspected less frequently than pipelines.
Several factors explain this:
- traditional inspection requires confined space entry
- operations are time-consuming and costly
- safety constraints are significant
As a result, inspections are often delayed, incomplete, or avoided altogether.
A New Approach with 360° Inspection
Modern technologies are changing this reality. With solutions like the RV-MAX 360 by RinnoVision, it is now possible to inspect a manhole in just a few minutes, without requiring confined space entry.
High-definition 360° video capture provides a complete view of the structure, allowing rapid detection of cracks, joint defects, infiltration points, and signs of corrosion or deterioration. This approach not only improves team safety, but also enhances inspection speed and data quality.
Move Toward More Effective Inspection
Manholes are far more than simple access points—they are critical areas where defects and risks concentrate within sewer networks.
Ignoring them means overlooking a significant portion of network issues.
By integrating manhole inspection into a proactive strategy and leveraging modern technologies, it becomes possible to better control infiltration, prevent failures, and optimize infrastructure management.
With RinnoVision, inspect your manholes quickly, safely, and with unmatched precision.
Request a demo of the RV-MAX 360 today.
FAQs
How do manholes contribute to infiltration?
Manholes have multiple entry points and are directly exposed to groundwater and surface water, making them a major source of water entering the network.
Why are manholes often under-inspected?
Traditional inspection methods require confined space entry, which is time-consuming, costly, and involves safety risks.
What is the best way to inspect manholes?
360° inspection cameras provide a fast, safe, and comprehensive solution for inspecting manholes without confined space entry.