Down the Manhole with a Camera: What a Drain Survey Actually Proves Before You Buy

Most house purchases in the North West follow the same rhythm: a viewing, a bit of hopeful maths, an offer, then a flurry of surveys booked in a panic before anyone changes their mind. HomeBuyer reports, electrical checks, a gas safety certificate if you're thorough. And then, at the bottom of the list, the drain survey — the one that gets trimmed when the budget starts groaning.

That's a shame, because it's usually the least expensive item in the pile and the only one that looks inside the part of the property you'll never see again until something goes badly wrong. Here's what it actually delivers.

What the camera is really doing down there

A drain survey is a surprisingly low-tech job dressed up in high-tech kit. An engineer lifts a manhole cover — the inspection chamber, if we're being tidy about it — feeds a rigid rod-mounted camera down the pipe, and watches a live feed on a small monitor while recording it. Most rigs have a pan-and-tilt head and a sonde, which is a transmitter that lets the operator trace the pipe's route and depth from above ground with a locator.

Over the course of an hour or two, that produces three useful things: a video file of the inside of your future drains, a written report with each stretch of pipe given a condition grade, and — crucially — a plan drawing showing where the pipes actually run. In older North West housing, that last bit is worth the fee on its own. Victorian terraces around Salford and Ancoats were never built with drawings anyone kept, and half the extensions, outbuildings and rear yards added since have quietly rerouted things.

When to book one, and what it costs

Standard advice: after your offer is accepted and before you exchange contracts. That's the window where you still have leverage.

A domestic CCTV survey typically runs somewhere in the region of £150 to £350 on a straightforward property, rising if there are multiple chambers, if the pipe has to be jetted first to see anything, or if you want the sewer run traced to the main. A basic one- or two-run inspection is at the lower end; a full internal and external survey on a large period house with a long garden run sits at the top.

Two things to check when you get quotes. First, whether jetting is included — a camera looking through a pipe half-full of silt and grease is a camera looking at nothing, and some firms charge that as an extra. Second, whether you get the video file, not just the summary. You paid for it; ask for it.

If the property is a period build, has mature trees within a few metres of the drain run, has had an extension or a dropped kerb, or the vendor can't tell you when the drains were last touched, book one. If nothing else, you'll start ownership with a map.

Reading the report without spiralling

Survey reports grade pipe condition section by section, usually on a scale where 1 is as-new and 5 is "this pipe has effectively stopped being a pipe." The scary-looking scores are rarely the whole story.

Here's the rough translation:

• Grade 1–2: Fine. Minor scaling or a bit of light debris. Nothing to act on.
• Grade 3: The interesting middle. Cracks, a displaced joint, some root ingress, slight deformation. Repairable, often without digging — but you want to know about it and price it in.
• Grade 4: Significant. A pipe that's lost structural shape, heavy root intrusion, a partial collapse. Usually means excavation or a lining job.
• Grade 5: Failed. Collapsed, blocked, or effectively missing.

A grade 5 on a short run of pipe under a lawn is a quote for a few hundred to a couple of thousand pounds. The same grade under a conservatory floor, a driveway or a mature tree is a different conversation entirely. Location matters more than the number.

Also watch for the phrase "foul water" versus "surface water." Confusing the two leads people to panic about the wrong pipe — surface water drains are the ones that overflow harmlessly onto a patio in a downpour; foul drains are the ones you actually care about.

Bargaining chips versus walk-away warnings

Most findings are negotiable. Root ingress at a joint, a section of cracked clay, a partially blocked run, a collapsed gully in the back yard — these are all standard and all priceable. Ask for the repair estimate in writing, then either ask the vendor to knock it off or to have the work done before completion. A seller who's genuinely motivated will usually meet you somewhere sensible.

Genuine red flags are rarer, but they exist. A collapsed drain running beneath a neighbouring property, or beneath a shared structure you don't control, gets legally awkward fast. A property with no accessible inspection chamber anywhere and a run that can't be traced is a project, not a purchase. And if the survey reveals that the drainage serves multiple properties and responsibility has never been formally established, that's a conversation for your solicitor, not your drain engineer.

One genuinely historical note worth knowing: since October 2011, many previously private sewers and lateral drains that connect to the public network transferred into water company ownership. So some of what looks like "your" pipe on a survey may not be yours to fix at all. Worth a phone call to United Utilities to check before you negotiate over something you'll never be billed for.

What the camera can't tell you

A drain survey is a snapshot of pipe condition. It is not a guarantee of future performance, and it doesn't cover everything.

It won't tell you how the drains behave after three days of October rain in a town with a combined sewer. It won't assess a septic tank or treatment plant's capacity or discharge quality — that's a separate job. It won't test your water supply, your boiler, or the soakaway under the lawn. And it won't identify a bodged DIY connection hidden behind a wall unless the camera happens to go past it.

It also doesn't replace your own eyes on a viewing. The survey confirms and prices what you spotted — the sunken patio, the drain cover sitting proud of the paving, the damp patch at the base of the rear wall, the smell near the back door. Those clues tell you where to point the camera. The camera tells you what it'll cost.

The sensible sequence

View the house. Note every cover, gully and suspicious dip in the paving. Make your offer. Book the survey inside the window before exchange. Read the report with the grades in one hand and a repair quote in the other. Then negotiate on the things that have a number attached, and get proper legal advice on the things that don't.

It's a couple of hundred quid and a morning of someone else's time. Compared with discovering a collapsed drain under your new driveway in February, it's the best-value hour in the whole process.