What is a Longitudinal fracture

A longitudinal fracture is a specific type of structural failure in underground pipework, characterised by a crack or split running along the length of a pipe. These fractures commonly originate at or near a pipe joint and gradually extend over time due to physical stress, material fatigue, ground movement, or hydraulic pressure. Although not always immediately visible from the surface, longitudinal fractures can lead to significant issues within a drainage or sewer system, particularly if left unaddressed.

This type of pipe defect allows wastewater or clean water to escape into the surrounding soil, which can result in environmental contamination, structural instability of adjacent buildings, and eventual ground subsidence.

Characteristics of a longitudinal fracture

Unlike circumferential or radial cracks, which run around the circumference of a pipe, a longitudinal fracture follows the direction of flow. It can range in severity from a hairline split to a wide-open gap that compromises the pipe’s structural integrity. In most cases, it will occur in rigid materials such as vitrified clay, asbestos cement, or brittle plastics, although metal and concrete pipes are also susceptible under certain conditions.

Key signs and consequences of a longitudinal fracture include:

  • Water loss from the drainage system into the surrounding soil

  • Formation of sinkholes or subsidence above the damaged pipe

  • Unusual damp patches or vegetation growth near the location

  • Blockages caused by soil or roots entering through the fracture

  • Rodent ingress through exposed openings

The risk increases in ageing or poorly installed systems, particularly where pipes are exposed to external loading from traffic or shifting soil.

Common causes

Several factors may contribute to the development of a longitudinal fracture, either alone or in combination. These include:

  • Poor-quality installation, especially at pipe joints

  • Thermal expansion and contraction causing material stress

  • Settlement or movement of surrounding ground

  • Hydraulic shock from high-pressure flow or surges

  • Tree root intrusion causing mechanical stress

  • Corrosion or chemical degradation in reactive soils

Pipes that have experienced repeated blockage clearance using mechanical equipment may also be more prone to cracking, particularly if aggressive techniques have weakened the pipe wall.

Detection and assessment

Longitudinal fractures often go undetected until symptoms become visible at ground level. To confirm and assess such damage, drainage professionals typically use:

  • CCTV drain surveys to visually inspect internal pipe conditions

  • Water pressure tests to identify leaks or drops in system integrity

  • Dye tracing to track fluid migration through suspected fractures

  • Ground-penetrating radar (in complex or sensitive locations)

Accurate detection is essential not only for repairing the current fault but also for identifying any underlying conditions that may affect the rest of the drainage system.

Repair options

Fortunately, most longitudinal fractures can be repaired effectively without the need for full excavation. The choice of repair method depends on the severity of the crack, location, pipe material, and access conditions.

The most commonly used repair techniques include:

  1. Patch lining
    A short sleeve impregnated with resin is inserted into the pipe at the damaged area and cured in place. This seals the fracture and restores flow continuity with minimal disruption.

  2. Full-length drain lining
    When access is sufficient and the pipe is damaged along a longer section, a continuous liner can be installed inside the host pipe to create a new, watertight inner surface.

  3. Excavation and pipe replacement
    In cases where the pipe is collapsed, severely deformed, or inaccessible for lining, excavation may be necessary. This is more disruptive and costly but may be required in heavily trafficked or sensitive areas.

  4. Pipe bursting
    A trenchless method where the damaged pipe is fractured and replaced with a new one by pulling it through the existing alignment. Used mostly for extensive damage or upsizing.

If the damage is minor and caught early, the repair process is straightforward and cost-effective, particularly with modern no-dig technologies.

Preventive measures and long-term solutions

To minimise the risk of longitudinal fractures in drainage systems, several preventive strategies can be adopted:

  • Use of flexible jointed pipes to absorb ground movement

  • Ensuring proper compaction and bedding during installation

  • Regular inspection and maintenance of older networks

  • Avoidance of chemical discharges that may degrade pipe materials

  • Early intervention on signs of partial blockages or subsidence

In new developments, proper design and adherence to material standards greatly reduce the likelihood of longitudinal fractures occurring during the system’s service life.

Environmental and structural risks

One of the most concerning consequences of a longitudinal fracture is the potential for subsidence. As water leaks into the surrounding soil, it can cause erosion or washing away of fine particles, leading to voids and instability beneath roads, pavements, or building foundations. Over time, this may result in structural cracks, tilting, or full collapse if left unresolved.

Additionally, fractured pipes carrying foul sewage pose a risk to groundwater and can lead to contamination of nearby wells, watercourses, or even basements. For this reason, early detection and repair are essential not only from a maintenance perspective but also for environmental and public health protection.

Conclusion

A longitudinal fracture in a drainage pipe is a common yet potentially serious defect that can compromise system performance, cause ground movement, and result in costly repairs if not addressed promptly. Fortunately, with modern inspection tools and trenchless repair methods, most cases can be resolved efficiently and economically.

Property owners, facility managers, and civil engineers should remain alert to the signs of such damage and ensure that routine inspections and preventative measures are in place. When dealt with early, a longitudinal fracture can be repaired with minimal disruption, extending the life of the drainage system and maintaining the safety and stability of the surrounding environment.