How to Find Clogs or Other Defects in a Wastewater System

How to Find Clogs or Other Defects in a Wastewater System

If you work in the water and wastewater systems world, having a simple way to explain the pitfalls of protecting this precious resource is important. If you are someone with little to no experience in water and wastewater infrastructure management, you may be in search of basic, and easy-to-understand information. GPRS offers you the following “wiki” on the industry and the biggest problems wastewater managers face – maintenance to control inflow and infiltration and contamination.

Wastewater systems are crucial for maintaining public health and environmental quality by transporting sewage and other waste away from homes and businesses to treatment facilities.

These systems are susceptible to problems such as clogs, defects, and other obstructions, which can lead to severe issues like cross bores, inflow/infiltration (I/I), and soil contamination. Identifying and addressing these problems promptly is essential to ensuring the efficient and safe operation of wastewater infrastructure.

Understanding Common Problems in Wastewater Systems


Clogs are blockages that prevent the normal flow of wastewater through the system. They can be caused by various materials, including fats, oils, grease, sanitary products, and debris. Clogs can lead to backups, overflows, and potential health hazards.

Cross Bores

A cross bore occurs when a utility line, such as a gas or electric line, unintentionally intersects with a wastewater pipe during construction or installation. This can create a significant safety hazard, as it may lead to gas leaks or electrical faults.


Inflow and infiltration (I/I) refer to the unintended entry of stormwater or groundwater into the wastewater system. Inflow typically enters through direct connections like downspouts or drains, while infiltration seeps in through cracks, joints, or defects in pipes. Excessive I/I can overwhelm the system, causing overflows and increasing treatment costs.

Soil Contamination

Soil contamination occurs when leaks or breaks in wastewater pipes allow untreated sewage to seep into the surrounding soil. This can pose serious environmental and health risks, contaminating groundwater and harming ecosystems.

A GPRS Project Manager lowers a push-fed sewer inspection scope into a manhole.
Promptly identifying and addressing problems with your wastewater infrastructure is essential to ensuring the efficient and safe operation of wastewater infrastructure.

Techniques for Detecting Clogs and Defects

Closed-Circuit Television (CCTV) Inspection

CCTV inspection is a widely used method for examining the interior of wastewater pipes. It involves sending a small camera mounted on a flexible cable through the pipeline to capture real-time video footage.

How It Works:

The camera is inserted into the pipe through an access point, such as a manhole. It is then remotely controlled to navigate the pipe, capturing high-resolution images of the interior.


  • Detailed Visualization: Provides a clear view of the pipe’s condition, allowing for precise identification of clogs, cracks, and other defects
  • Non-Destructive: Does not require excavation or disruption of the surface
  • Documentation: Creates a record of the pipe’s condition for future reference


  • Preparation: Clean the pipeline using jetting or other methods to remove debris that may obstruct the camera
  • Insertion: Introduce the camera into the pipeline and begin the inspection
  • Analysis: Review the footage to identify any abnormalities, such as clogs, cross bores, or signs of I/I

Smoke Testing

Smoke testing is used to identify sources of inflow and infiltration by introducing non-toxic smoke into the wastewater system and observing where it exits.

How It Works:

Smoke is generated and blown into the sewer lines using a smoke machine. The smoke follows the path of least resistance, escaping through defects or improper connections.


  • Effective for I/I Detection: Quickly identifies areas where stormwater or groundwater is entering the system
  • Cost-Effective: Relatively inexpensive and easy to perform
  • Visible Results: Provides immediate, visible evidence of leaks or improper connections


  • Preparation: Notify residents and businesses in the area to prevent unnecessary alarm
  • Smoke Injection: Introduce smoke into the system using access points like manholes
  • Observation: Watch for smoke emerging from the ground, manholes, or building connections, indicating a potential defect

Dye Testing

Dye testing involves adding colored dye to the system to trace the flow of water and identify leaks or improper connections.

How It Works:

Dye is added to water sources suspected of contributing to inflow, such as roof drains or sump pumps. The dye’s path is then traced through the system to see where it appears.


  • Effective for Identifying Cross Connections: Useful in finding sources of inflow or cross bores
  • Visual Confirmation: Provides a clear visual indication of where water is entering or exiting the system
  • Non-Toxic: Uses harmless, biodegradable dyes


  • Dye Introduction: Add dye to suspected inflow sources
  • Observation: Monitor downstream points for the appearance of dye to identify improper connections or leaks

Acoustic Inspection

Acoustic inspection uses sound waves to detect changes in the flow or the presence of obstructions within the pipes.

How It Works:

Acoustic sensors are placed on the surface or inside access points to listen for variations in sound that indicate changes in flow or the presence of blockages.


  • Non-Invasive: No need for excavation or disruption of the pipeline
  • Real-Time Detection: Provides immediate feedback on the condition of the pipe
  • Effective for Clogs: Can detect blockages or changes in flow that suggest the presence of clogs


  • Sensor Placement: Position sensors at various points along the pipeline
  • Sound Analysis: Listen for changes in the acoustic signals that may indicate a clog or defect
  • Data Interpretation: Analyze the data to pinpoint the location and nature of the issue

Trenchless Technology

Trenchless technology encompasses various methods for inspecting and repairing pipes without extensive digging. This includes pipe bursting, sliplining, and cured-in-place pipe (CIPP) techniques.

How It Works:

These methods involve minimal excavation and use specialized equipment to repair or replace pipes from within.


  • Minimal Disruption: Reduces surface disruption and associated costs
  • Efficient Repairs: Allows for quick and effective repair of defects
  • Versatile: Applicable to various types of pipes and defects


  • Site Assessment: Evaluate the site and determine the appropriate trenchless method
  • Preparation: Set up equipment and access points for the chosen technique
  • Execution: Perform the repair or replacement using trenchless methods.

Addressing and Preventing Soil Contamination

Soil contamination from wastewater leaks can have serious environmental and health impacts. To address and prevent contamination:

  • Immediate Response: Promptly repair leaks and defective pipes to prevent further soil contamination
  • Monitoring: Regularly inspect and monitor the system for signs of leaks or defects
  • Protective Measures: Implement protective measures, such as pipe lining or coatings, to reduce the risk of leaks

GPRS Video Pipe Inspection is a sewer inspection service that uses industry-leading remote video cameras to assess conditions and prevent problems in water, sanitary and storm sewer, and lateral pipelines. Our NASSCO-certified Project Managers scope your sewers to locate clogs, identify cross bores, find structural defects & damages, and conduct lateral sewer line inspections. We provide you with comprehensive, interactive reporting that details every inch of your pipes to help you plan repairs, maintain your system integrity, and mitigate risk.

From skyscrapers to sewer lines, GPRS Intelligently Visualizes The Built World® to keep your projects on time, on budget, and safe.

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