What a CCTV drain survey actually shows, and when it is worth the money
A camera survey turns a guess about the state of a drain into a record of what is there, where it sits and how deep. Here is what it finds and when it pays for itself.
The camera answers three questions
Is the pipe sound, where exactly is the problem, and how deep is it. Everything useful about a survey comes from those three answers, and the third is the one people forget.
Footage on its own tells you a drain has a crack somewhere. Footage with a locator reading tells you the crack is 6.4 metres from the chamber at 900 mm depth, under the left-hand side of the drive. The first is a video. The second is a repair plan that keeps excavation to a small hole.
What gets found, and how it is classified
Findings split into two groups, and the distinction sets the urgency.
Structural defects affect the pipe itself: cracks, fractures, deformation, collapse, displaced joints, missing sections. These do not improve on their own and they set a timescale.
Service defects affect performance without damaging the pipe: deposits, root growth, standing water, encrustation, an obstruction. Many of these can simply be cleared, though the ones that keep coming back usually have a structural defect behind them.
Two findings dominate in London. Standing water where the pipe should have drained, which means a dip, a reverse fall or a restriction further along. And root ingress at clay joints, which is the leading cause of repeat blockages in period housing.
The four situations where it pays
- A drain that keeps blocking. Second clearance in a year: stop clearing, start looking.
- Buying a property. A standard homebuyer survey does not look inside the drains. For older housing with mature trees, that is the expensive gap.
- An insurance claim. Insurers want the defect documented with position and likely cause, in a form they can assess.
- Before building. An extension going over a drain needs the run located accurately first, not discovered by a digger bucket. More on that in planning an extension.
What the report should contain
Footage plus a written summary listing each observation, its position along the run, its severity and a recommendation. Written so a surveyor, an insurer or a builder can act on it without ringing you for clarification.
If a contractor offers footage with no written interpretation, ask what you are meant to do with it. The report is the part that has value six months later.
Where surveys come up most in London
We survey heavily in areas with mature trees and older clay pipework: Richmond, Dulwich and Wimbledon in particular, where excavation under an established garden or a block-paved drive is the expensive part and knowing exactly where to dig changes the price of the repair substantially.
Pre-purchase surveys cluster in the same places, for the same reason.