What a CCTV Drain Survey Actually Is

On a normal domestic drain — 100mm or 110mm pipe running from the house to the boundary — the camera rides on the end of a semi-rigid push rod, which is fed in from an inspection chamber in the front or back garden. The head is a self-levelling colour camera with its own ring of LED lighting, so the picture stays the right way up as the rod turns through the bends. On the larger shared and public sewers, where a push rod is not enough, we use a wheeled crawler instead. Either way the whole run is recorded to a hard drive and the position of every defect is measured and logged as we go, using a sonde and locator to confirm depth and line above ground.

Everything that comes back gets coded to the standard the industry uses, the WRc Manual of Sewer Condition Classification. You will see two families of code. Structural codes cover the pipe itself: cracks, fractures, open joints, displaced joints, deformation, brick loss in old sewers and outright collapse. Service codes cover what is inside it: roots, debris, silt, grease, encrustation and infiltration, where groundwater is finding its way in through a defect. Both are graded, normally one to five, where one is a minor blemish and five is a hole you can see daylight through the wrong way. A report from a properly equipped survey will read like a sentence about your drains rather than a photo of a pipe — and that is the point of it.

What a CCTV survey is not is a substitute for clearing the drain first. The camera cannot see through standing water. If the run is blocked or holding water when we arrive, the honest answer is that it has to be jetted clean before the survey means anything — otherwise you are filming the top of a blockage instead of the pipe underneath it. If you are not sure which job you need, our guide to blocked drains in Wandsworth is the place to start, and if it turns out the run needs scouring we will do that first and survey after.

Why Wandsworth Drains Get Surveyed More Than Almost Anywhere

Wandsworth is not a hard borough to understand once you look at the ground under it. Three things combine here in a way they do not in most of London.

The pipe is very old in the north of the borough. Battersea, Clapham Junction, Wandsworth Town and the streets behind St John’s Hill were built out in the middle of the nineteenth century, largely with salt-glazed clay pipes laid in short lengths and joined by hand. After 150 years of tree roots, ground movement and heavy traffic, those joints have moved. Small separations at the joints are the single most common structural defect we find in SW11 and SW18.

The soil moves, and it moves differently across the borough. North of the commons you are largely on London Clay, which swells and shrinks through the year and takes drain runs with it. Down in the Wandle valley at Wandsworth Town and Earlsfield, and along the Thames at Battersea, you are on river terrace gravels with a high water table after a wet winter — which is how silt and groundwater get into exactly the open joints that Victorian builders left behind. The higher ground around Wandsworth Common, Putney Heath and Roehampton sits on gravels and sands that drain fast and then dry out hard. A run built across a clay-to-gravel transition will usually fail at the transition.

People keep digging. Wandsworth has one of the highest concentrations of basement and multi-level basement conversions in the country. Nearly every house that gets one needs a drainage strategy with the planning application, and nearly every one of those needs to know where the existing pipes run and how deep, before anything gets excavated. The same is true of the rear and side extensions that go up constantly through Balham, Tooting, Earlsfield and Wandsworth Town — and there is a straightforward reason for that: a digger bucket through an unrecorded drain is one of the most expensive mistakes in domestic building work.

Add the watercourses. The Wandle runs through Wandsworth Town — a chalk stream, hard water, historically a working river — and is culverted in places. The Beverley Brook runs through the Putney and Roehampton side. The Falcon Brook has been buried under Battersea for well over a century. Where a stream has been culverted, the sewers around it tend to be the ones that surcharge first in a storm, and the flash flooding that hit the Wandle valley in July 2021 is the reminder everyone in Earlsfield and Wandsworth Town remembers.

None of that is a reason to panic about owning a house here. It is a reason to know what your drains look like before you find out the hard way.

Five Wandsworth Situations Where a Survey Pays for Itself

1. Buying a house. Wandsworth changes hands at prices where a four-figure repair is a rounding error on the negotiation but a genuine surprise afterwards. A pre-purchase survey before you exchange gives you the facts while you still have leverage: either the seller fixes it, or the price reflects it, or you buy with your eyes open. This is the single largest share of the surveys we run in SW11, SW12, SW17 and SW18.

2. Extending, converting a loft, or digging a basement. Current build-over guidance means a public sewer within about three metres of new foundations or a new structure needs agreement from Thames Water before you build, and a survey is what tells you whether you have one there. Underground pipework also needs to be traced before piles, footings or slabs are set out. Finding a sewer on paper is fine; finding it with a bucket is not.

3. The drain that keeps coming back. If a run blocks two or three times a year, the cause is nearly always physical: an open joint pulling in silt, a root that regrows from the pipe wall, or a length of pipe that has lost its fall and holds water permanently. Jetting buys you months. A survey tells you which of the three it is, and whether the fix is a patch lining, a localised repair or a full reline of that section.

4. Shared drains and the neighbours. Since the private sewer transfer in October 2011, the shared length of drain serving two or more properties — and the run under the public highway — is generally the water authority’s responsibility, not yours. In a converted Wandsworth terrace with three flats sharing one back-garden run, that is often the difference between a bill and no bill. In practice Thames Water will usually want camera evidence before they accept it, which is exactly what a survey produces. On the Battersea side it is also worth knowing that the Tideway connection at Falconbrook has cut the number of storm overflows into the Thames in that reach — good news for the river, but it does not change who owns your lateral.

5. A damp patch, a smell, or a subsidence claim. Damp at the base of a wall, a drain smell in a cellar, or a crack that an insurer is asking about will all point at the same question: is the pipe leaking below ground? A survey answers it with film and codes, and either rules the drains out or gives you something an insurer and a loss adjuster can actually work with.

For a straightforward three- or four-bedroom Wandsworth house with two or three runs to survey, expect a domestic CCTV survey to land somewhere in the region of a few hundred pounds — less than a single emergency excavation, and dramatically less than a repair done wrong. We give a fixed price on the phone before we come out.

Reading the Report: What Matters and What Does Not

A good survey report is short, plain and boring. You want the survey drawing showing the run of pipe and the depth at each chamber, the coded condition of each length, the footage itself, and a recommendation that says what to do, in order of urgency. Everything else is packaging.

When you read yours, grade 1 and 2 defects are almost always leave-alone material — hairline crazing, light encrustation, a bit of root growth that has been jetter-cut and is not obstructing flow. Grades 3, 4 and 5 are where the money is: a pipe deformed into an oval that snags everything passing through it, a displaced joint sitting half a pipe-width out of line, significant root ingress, or a section that has lost its fall and holds water.

Two things are worth saying plainly, because they are where homeowners most often get sold something they do not need. First, not every defect needs digging up. A displaced joint at 2m depth under a patio can often be patch-lined from the inside for a fraction of the cost of excavation. Second, a survey is a snapshot of the day it was carried out. Roots regrow, and a clean pipe at purchase can be root-affected three years later. It is evidence, not a warranty.

If you have already had a survey done by somebody else and are not sure what you are looking at, call us and read it out — we will tell you honestly whether it says what you have been told it says.

On the Day: What We Need From You, and the Limits

Access is the main thing, and it is usually simple. We need to get at the inspection chamber or chambers on the run — front garden, side return, back garden or a driveway gully — and the covers need to be liftable. On properties where the only chamber is under a slab, a deck, a new patio or a neighbour’s land, or where an internal run has no external access at all, we may need to survey from inside the house through a lifted WC pan or an access plug. We will tell you on the phone if that applies to you, because it affects how long we need.

A typical three- or four-bedroom house with two or three runs takes an hour or two, sometimes more if the pipework is complex or there is a lot to jet first. Floors and paths get protected, the camera and rods get a quick clean indoors before they come back through the house, and coverage is left as we find it. Footage and a written report normally follow within a day or so.

And the honest limits, because a survey cannot do everything. The camera will not see below the water line, so a blocked or holding drain has to be cleared first. It cannot assess a pipe running beneath a solid concrete slab with no access to it. It cannot predict future root growth. What it can do is show you the inside of a pipe you cannot otherwise see, which is the whole reason we use it — before jetting a fragility into a collapse, before a builder digs, and before you buy.

Posted by HydraFlow — drainage and plumbing specialists covering London. We provide CCTV drain surveys, blocked drain clearance, CCTV surveys, high-pressure drain jetting and emergency drainage services across Wandsworth, Battersea, Balham, Earlsfield, Furzedown, Nine Elms, Putney, Roehampton, Southfields, Tooting, Wandsworth Town and South West London.