A CCTV drain survey in Farnham: what we found

A recent CCTV drain survey in Farnham showed why a drain can appear to be working while still needing attention. Water was passing through the surveyed pipework at the time, but the camera recorded defects in several clay drainage runs that could allow leakage, hold debris and worsen over time.

The survey also raised wider questions for the property: how to protect drainage beneath an extension, whether to move an internal access point, and how rainwater should be managed separately from foul drainage.

What the camera found

The affected clay pipework included multiple fractures, displaced pipe joints and a hole in one short branch. A displaced joint means that adjoining pipe sections are no longer lined up properly. As well as interrupting the internal flow path, this can create an opening for water to escape or for surrounding ground to enter the pipe.

Roots had entered one severely displaced joint on the run towards the sewer. Roots often exploit openings rather than creating them from nothing, so clearance alone would not resolve the underlying issue: the joint also needs to be sealed or otherwise repaired.

The survey found that other inspected branches were acceptable. This is important: a CCTV survey distinguishes between the parts of a drainage system that need work and those that do not, based on the condition actually recorded.

Why adequate flow did not mean the drains were sound

At the time of inspection, the affected runs were carrying flow. That did not remove the concern.

Fractures and open or offset joints can:

• provide routes for wastewater to leak into the surrounding ground;
• allow fine material to be washed away from around the pipe;
• create places where debris can catch;
• permit root ingress; and
• leave the pipework more vulnerable to further movement or collapse.

The section beneath the existing extension needed particular care. Newer plastic sections had been installed where previous work had affected the drainage, but the connections were poorly aligned and showed leakage. The survey indicated likely loss of supporting material around this area, allowing the pipe to sag.

A sag is a low point in a drain. Water may still travel through it, but solids can be more likely to settle if the fall — the downward slope that carries drainage by gravity — is inadequate. Repeated joint offsets and an incorrectly positioned connection also had an adverse effect on flow through this part of the system.

The proposed repair approach

The recommendation was to address the four affected clay runs as a coordinated repair, rather than treating each defect in isolation.

The proposed scope included local cured-in-place point repairs at the short branches and at clay-to-plastic connections. A point repair is a local fibreglass liner installed inside a damaged section of pipe to seal and reinforce it without excavating the full length.

A longer polyester liner was proposed for the run beneath the extension after the local connection repairs. The objective was principally to seal leaks, reinforce the pipe and reduce the risk of further loss of surrounding material and joint movement.

However, lining has limits. A liner can seal and reinforce a pipe, but it may not be able to lift a sagging pipe or replace missing support beneath it. If restoring the pipe level or correcting its gradient proves necessary, excavation may be required. This is why the distinction between sealing a defect and correcting the pipe’s physical position matters.

The run towards the sewer also required root clearance before sealing. It was in better condition than the section beneath the extension, so the proposed liner was expected to offer a less disruptive repair option for that run.

For homeowners considering similar work, our drain relining service explains where lining can be suitable, while drain repair may be needed where access, alignment or support cannot be resolved from inside the pipe.

Internal access and future maintenance

The survey considered whether an existing internal inspection chamber could be removed or relocated. An inspection chamber is an access point that allows drains to be inspected and maintained.

Converting it to a continuous pipe was considered feasible in principle, but only if replacement external access and suitable drainage connections are properly designed. The recommendation was to provide a new external manhole, route the relevant toilet branch directly to it and rearrange other foul connections as appropriate. The rainwater connection would need to be diverted separately.

Keeping the internal chamber was also an option, with a suitable double-sealed cover considered. The survey did not regard this as necessary if the access could be rearranged. A displaced sealing gasket was found inside the chamber and was reseated; it had reportedly been disturbed during earlier lid lifting.

Any change to access points or pipe routes needs to maintain practical maintenance access and adequate gravity falls. The survey indicated that the sewer outlet appeared deep enough to accommodate gravity drainage from the property, subject to confirming final routes, connection levels and falls.

Rainwater was adding flow to defective pipes

Two rainwater connections were recorded discharging into the foul drainage. This increased the volume passing through pipes already affected by defects and could aggravate leakage.

The recommendation was to divert rainwater to a garden soakaway if testing confirms that the ground can absorb the runoff and a suitable location is available. Groundwater conditions and the building’s position would also need to inform the design.

A separate stormwater pipe could not be inspected because access was obstructed. It was not traced into the foul system, but its condition and final discharge point therefore remain unconfirmed. This is a useful reminder that a survey can only report on the pipework it can access and see.

Where soakaway drainage is being considered, BRE 365 percolation testing helps establish whether the ground is suitable.

What this means for homes nearby

This survey does not show that neighbouring homes have the same drainage defects. Each property’s pipe routes, alterations, ground conditions and maintenance history can differ.

It does show why assumptions based on whether a drain is currently flowing can be misleading. A camera survey can identify hidden fractures, displaced joints, root ingress and connection problems before a visible failure develops. It can also help separate issues that may be addressed with lining from those that may need excavation or a redesigned connection.

For anyone buying, extending or investigating recurring drainage concerns in Farnham, it is also sensible to establish responsibility for the pipes involved. In this case, the affected drains were recorded as private, with responsibility to be confirmed through the drainage search and title documents. The survey also recommended checking records relating to the existing extension, including its drainage approvals and building-control documentation.

If you are concerned about the condition or route of drains at your property, request a quotation for a CCTV drainage survey or appropriate repair assessment.