What Is a CCTV Float Survey?
A CCTV float survey is a specialist sewer inspection method used where water levels are too high for conventional crawler cameras to operate effectively. Instead of travelling along the invert of the pipe on wheels, a float-mounted camera system is positioned on a buoyant platform that moves with the live sewer flow.
The camera is stabilised and guided from the surface using tethered cabling and control systems, allowing engineers to capture high-quality visual footage even in full or near-full flow conditions. This method is particularly effective in large-diameter trunk sewers, culverts, and combined systems where flows cannot be diverted without major operational disruption.
Float surveys are commonly deployed in brick-built culverts, historic sewer networks, and infrastructure assets where maintaining live flow is essential.
Why Aren't Standard Crawler Cameras Always Suitable?
Under normal conditions, crawler cameras operate by travelling along the base of a pipe, transmitting live footage back to engineers above ground. This works well when flows are low and the pipe invert is visible.
However, crawler systems have clear limitations in high-flow environments. When water levels rise above the camera lens, visibility is lost. Turbulence can destabilise the unit, and strong currents may prevent controlled movement. In egg-shaped or brick-built sewers, uneven surfaces and structural irregularities can further restrict crawler access.
In these circumstances, attempting a standard CCTV survey may provide incomplete data or present safety risks. A float survey offers a safer and more reliable alternative.
When Is a Float Survey Required?
CCTV float surveys are typically required in situations where:
- Sewer flows are consistently high and cannot be reduced.
- Combined sewer systems are carrying both foul water and stormwater.
- Large-diameter trunk sewers or culverts operate under live conditions.
- Brick egg culverts or historic structures prevent stable crawler operation.
- Flow diversion is impractical, unsafe, or operationally disruptive.
Choosing the right inspection method ensures an accurate diagnosis of the problem without compromising safety or service continuity. Moreover, as part of your planned preventative maintenance of your drainage systems, a CCTV float survey could offer a more effective survey, depending on your drainage specifics.
Case Study: Brick Egg Culvert Inspection in Liverpool
During a recent project in Liverpool, NRC WWS carried out a CCTV float survey within a 1600mm x 1100mm brick egg culvert operating under live flow conditions. The culvert’s dimensions and continuous flow made a traditional crawler inspection unsuitable.
Using a float-mounted system, engineers were able to complete a full visual assessment of the structure without diverting the flow. The survey enabled accurate identification of structural defects, infiltration points, joint displacement, and debris accumulation.
Brick egg culverts, particularly historic assets, present unique inspection challenges. Float survey capability allows these critical infrastructure components to be assessed safely while maintaining operational continuity.
Find out more about how drain surveys and inspections can help protect your business.
Float Survey vs Crawler CCTV Survey
Both methods have distinct advantages depending on site conditions.
Crawler CCTV surveys are ideal for low-flow or dry pipelines where stability and close-up defect analysis are required. They provide highly controlled movement and detailed imaging of the pipe invert and walls.
Float surveys, by contrast, are designed for high water levels and live systems. They tolerate submerged environments and use buoyancy for movement rather than traction. While image clarity can be influenced by turbulence, specialist equipment ensures usable and actionable footage.
Operational safety is also a key differentiator. In high-flow environments, float surveys reduce the need for flow control measures and minimise confined space risk compared to attempting crawler deployment in unstable conditions.
Benefits of CCTV Float Surveys for Commercial and Industrial Sites
For commercial and industrial operators, CCTV float surveys offer several key advantages:
- They enable accurate defect identification within live systems without costly shutdowns.
- They reduce the need for excavation by pinpointing structural issues precisely.
- They minimise operational disruption across highways, utilities, and industrial facilities.
- They support asset management planning by providing reliable condition data.
By maintaining service continuity while delivering actionable inspection results, float surveys protect both infrastructure and operational performance.
Health, Safety, and Operational Considerations
High-flow sewer environments present significant risks. Confined space protocols, gas monitoring, rescue planning, and flow monitoring are essential.
Float surveys require specialist equipment and trained personnel capable of managing live sewer conditions. Risk assessments must consider hydraulic forces, access constraints, and environmental exposure.
Professional execution ensures compliance with health and safety legislation while delivering accurate technical results.
How NRC WWS Delivers Specialist Sewer Inspections
NRC WWS assesses each site to determine the most suitable inspection methodology, whether crawler CCTV, float survey, or a combined approach.
Our teams deploy specialist float-mounted systems supported by confined space-trained operatives experienced in high-risk environments. Clear, structured reporting provides defect classification, condition grading, and practical recommendations for remedial works.
Operating across Liverpool and surrounding regions, NRC WWS delivers responsive and technically robust sewer inspection services for complex infrastructure assets.
Contact NRC WWS For Specialist CCTV Drainage Surveys
Selecting the correct inspection method is critical in high-flow sewer environments. Attempting to use unsuitable equipment can compromise safety, data quality, and operational efficiency.
CCTV float surveys provide a reliable solution for inspecting live, high-capacity systems where crawler cameras cannot operate effectively.
Speak to NRC WWS about specialist CCTV float surveys and complex sewer inspections to ensure your assets are assessed safely and accurately.
