A CCTV drain survey puts a camera inside your drainage pipework to find cracks, blockages or collapses. Leak detection investigates pressurised clean-water and heating pipework instead, using acoustic, thermal and tracer gas methods. Waste water problems need a drain survey; a rising water bill or unexplained damp near supply pipework needs leak detection. Some cases need both.
Booking the wrong survey wastes time and money, and it happens more often than you’d expect, because a CCTV drain survey and a leak detection investigation sound similar but look for completely different things. One puts a camera inside a pipe. The other listens, reads temperature and uses tracer gas to find a leak it cannot see directly. This guide sets out what each covers, so you book the right one first. For supply-side investigations, see our guide to underground water leak detection.
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What a CCTV drain survey actually does
A CCTV drain survey pushes a waterproof camera on a flexible rod through a drain, gully or waste pipe, recording footage of the inside of the pipe as it travels. The operator watches the feed in real time, looking for cracks, fractures, root ingress, misaligned or open joints, scale build-up and full or partial blockages. Because the camera is physically inside the pipe, the findings are direct visual evidence rather than an inference from the outside.
This makes a CCTV survey the right tool whenever the problem sits in gravity-fed waste pipework, the drains that carry water away after you have used it, rather than the pressurised system that brings clean water in.
What leak detection actually does
Leak detection covers the clean-water supply pipe, central heating pipework and anything else running under constant mains or system pressure. A camera cannot usefully be threaded through most of this pipework, so the methods work differently:
- Acoustic sensors and correlators listen for the distinctive sound a pressurised leak makes as it escapes, even through a wall, floor or underground run.
- Thermal imaging reads surface temperature with a FLIR camera, highlighting the pattern that escaping water often creates on a nearby surface.
- Tracer gas, a safe mix of 5% hydrogen and 95% nitrogen, is introduced into the empty pipe and detected at the surface with a sensitive probe, pinpointing the exact spot.
These are the core techniques behind our plumbing leak detection service, applied to pressurised systems rather than gravity drainage.
CCTV drain survey vs leak detection at a glance
| Feature | CCTV drain survey | Leak detection |
|---|---|---|
| What it investigates | Waste and drainage pipework | Pressurised supply and heating pipework |
| How it works | Physical camera inside the pipe | Acoustic, thermal imaging, tracer gas |
| Best evidence for | Blockages, cracks, root ingress, collapses | Rising water bill, damp near supply pipework, moving meter |
| Result | Recorded footage of the defect | A pinpointed leak location for repair |
When each one applies
A CCTV drain survey is the right starting point when there’s a foul smell, slow-draining fixtures, a sunken patch of garden over a known drain run, or when you are buying a property and want direct evidence of drain condition. Leak detection is the right starting point when your water meter keeps moving with everything off, mains pressure has dropped, your water bill has risen unexpectedly, or a damp patch tracks back towards known supply or heating pipework rather than a drain. Our guide to drain leak or supply leak goes through these clues in more depth if you are still unsure which system is involved.
When you need both
Some properties genuinely need both investigations, particularly where supply and drainage pipework run close together underground or under a floor and the initial evidence is mixed. We see this most weeks on older properties where nobody has an accurate record of exactly where each pipe run sits. Rather than guessing and paying for the wrong survey first, a methodical approach rules each system in or out in turn, starting with whichever the evidence points to more strongly.
How to choose without guessing
- Check your water meter with everything off. If it’s moving, that points towards leak detection.
- Note the smell. Foul and sewage-like points towards drainage; little to no smell points towards supply.
- Note the timing. Constant dampness suggests a supply leak; dampness tied to a specific fixture being used suggests drainage.
- Look at the location. Close to a manhole, gully or garden drain run suggests drainage; close to a stopcock, boiler or known supply pipe suggests leak detection.
- If more than one clue conflicts, or you are unsure, ask for an assessment before booking, rather than choosing blind.
Cornwall and Devon: older pipe runs
Across Cornwall and Devon, older cottages, farm conversions and properties on private drainage sometimes have decades-old pipe runs with no clear record of layout. Coastal and rural properties in particular can have supply and drainage lines laid at different times by different hands, crossing paths in ways nobody documented. Private drainage is common on rural and farm properties here too, with septic tanks and private treatment plants feeding into runs that were never mapped when they were laid, which makes a CCTV survey especially useful before any digging starts.
On these properties, we often talk homeowners through the clues on the phone before recommending which survey to book first, so the first visit is the right one rather than the start of a process of elimination. Holiday lets add a further wrinkle: guests report a smell or a damp patch weeks after it started, so the timing clues that usually help narrow things down are less reliable, and starting with a broader check of both systems can be the more practical route.
Frequently asked questions
What does a CCTV drain survey actually check?
A CCTV drain survey feeds a waterproof camera through the drain or waste pipe to record the inside of the run in real time. It shows cracks, root ingress, collapses, misaligned joints and blockages directly on screen, rather than inferring a location from outside evidence.
What does leak detection check that a CCTV survey doesn’t?
Leak detection focuses on pressurised supply and heating pipework, which a drain camera cannot travel through in the same way. Acoustic sensors, thermal imaging and tracer gas are used instead, since a camera cannot easily be pushed through most clean-water supply pipes.
Do I need both a CCTV survey and leak detection?
Sometimes, yes. Where supply and drainage pipework run close together, or where the initial signs are ambiguous, both investigations may be needed to rule each system in or out. A combined approach is common on older properties where records of what runs where are incomplete.
How much does a CCTV drain survey cost?
DCI provides fixed prices upfront once the job is scoped, with no call-out fee. UK leak detection and drainage specialists more broadly tend to price this kind of survey work in the region of £500 to £1,500 depending on access and the length of run involved, though every job varies.
Can a CCTV drain survey find a water leak?
A CCTV drain survey finds defects inside drainage and waste pipework, not leaks in the pressurised clean-water supply. If the evidence points to mains water rather than waste water, non-invasive leak detection methods such as acoustic listening and tracer gas are the appropriate route instead.
Is a CCTV drain survey useful when buying a house?
It can be, particularly on older properties or where a survey has flagged drainage concerns. A CCTV drain survey gives direct visual evidence of the drain’s condition, which is more conclusive than guessing from surface signs like slow drainage or a damp patch near a manhole.
Does insurance cover a CCTV drain survey?
It depends on the policy and the cause. Escape of water cover is standard under most buildings insurance, and the Association of British Insurers notes that escape of water costs insurers about £1.8 million in payouts every day, but drainage-specific cover sometimes sits under a separate section, so check your policy wording.
Not sure which survey you need? Ask us first
Tell us what you’re seeing and we’ll recommend a CCTV drain survey, leak detection, or both, before you book anything, then carry it out across Cornwall & Devon with fixed pricing upfront.
Call Dickie on 07822 025 911 No Find, No Fee on residential leak detection (subject to terms)