How to Read a CCTV Drain Survey Report

By Josh Rickard July 11, 2026blog

TL;DR: A CCTV Drain Survey Report records what the camera found inside your drainage system. It uses standard WRc codes, distance markers, clock references and condition grades from 1 to 5 to describe every defect. Learn to read those four elements and you can see exactly which faults need fixing now, which can wait, and which are not yours to pay for.

Knowing how to read a CCTV Drain Survey Report is the difference between an informed repair decision and a blank cheque. Most reports open with a wall of codes: FL, JDM, DER, WL. Skip past them and you could authorise work you never needed, or miss the one defect that collapses the pipe next winter.

These reports are commissioned by homebuyers before exchange, by landlords documenting condition between tenancies, by builders applying for consent to build near a sewer, and by homeowners who have unblocked the same drain three times in a year. All of them receive the same thing: a video file, a site plan, a log of coded observations, and a set of condition grades.

The good news is that the format is standardised. Once you understand the four building blocks (the codes, the distances, the clock references and the grades), the report reads like a map rather than a foreign language. Here is how each part works, and how to turn it into a repair decision.

What Is a CCTV Drain Survey Report?

A CCTV Drain Survey Report is the written record of a camera inspection of your drainage system. It sets out what the engineer found, exactly where each fault sits, how serious that fault is, and what repair it calls for. The footage is the evidence. The report is the diagnosis.

A complete report is never just a video. You should receive:

• The survey footage, section by section, with on-screen distance readings
• A drainage schematic, showing manhole positions, pipe runs and direction of flow
• An observation log, listing every defect with a code, a distance and a grade
• Still images of each significant defect
• A summary and recommendations section, written in plain English

If your report contains only a video and a quote, it is not a survey report. It is a sales document. Ask for the observation log.

The Six Elements Every Report Should Contain

A drain survey report follows a set structure so that any qualified engineer can pick it up and reach the same conclusion. Reports are built to a common format for a reason: they are used as evidence in property transactions, insurance claims and water company applications, so they cannot be subjective.

Here is what each part tells you, in the order you will meet it:

1. Site details. Address, date, weather on the day, and the surveyor’s name and qualification. Weather matters. Heavy rain changes water levels inside the pipe and can hide defects below the flow line.
2. System data. Pipe material (vitrified clay, pitch fibre, PVC, cast iron), diameter in millimetres, and whether the run is foul, surface water or combined.
3. Node references. Every pipe run is surveyed between two points, normally manholes, labelled something like MH1 to MH2. This is how you locate a defect on the ground.
4. Direction of survey. Upstream or downstream. This decides which end of the pipe the distance measurements are counted from, and it is the single most misread field in the whole document.
5. The observation log. The heart of the report. One line per observation.
6. Grades and recommendations. The conclusion, and the part everyone reads first.

Get the node reference and survey direction straight before you look at anything else. A defect at 8 metres from MH2 running upstream is in a completely different place from a defect at 8 metres from MH1.

What Do the Codes on a Drain Survey Report Mean?

The codes come from the Manual of Sewer Condition Classification, the national defect coding standard published by WRc. WRc created the first sewer image coding structure in 1980, and the manual is now in its 5th edition. Every UK drainage engineer codes to the same standard, which is why a report from Falmouth reads identically to one from Manchester.

MSCC5 contains dozens of codes. In domestic surveys, the same handful appear again and again, and they fall into two groups that matter enormously for cost.

Structural Codes: Damage to the Pipe Itself

These describe physical failure of the pipe wall. They do not clear with cleaning.

• CC, CL, CM: crack, circumferential (around the pipe), longitudinal (along it), or multiple
• FC, FL, FM: fracture, circumferential, longitudinal, or multiple. A fracture is a crack that has opened, with visible displacement
• B: broken pipe, where pieces have moved out of position
• X: collapse. The pipe has lost structural integrity
• D: deformed, where the pipe has lost its round shape. Common in pitch fibre pipes laid in the 1950s and 1960s
• JDM, JDL: joint displaced, medium or large
• OJM, OJL: open joint, medium or large
• H: hole in the pipe wall

Service Codes: Things Inside the Pipe

These describe what is obstructing flow rather than what is wrong with the pipe. Many are cleaning jobs, not repair jobs.

• DER, DEG, DES: deposits attached as encrustation, deposits attached as grease, deposits settled on the invert
• RF, RM, RT: roots, fine, mass, or tap root
• IS, ID, IR, IG: infiltration, seeping, dripping, running or gushing. Water is entering the pipe from outside
• OB: obstruction
• WL: water level, given as a percentage of pipe diameter. A standing WL of 50% between manholes points to a downstream restriction
• SA: survey abandoned. Note the reason. An abandoned survey means part of your system was never inspected

Construction and Reference Codes

JN marks a junction, CN a connection, and LL, LR, LD, LU record where the line deviates left, right, down or up. These are not defects. They are landmarks.

Root codes deserve a word of their own in Cornwall. Cornish hedges and mature boundary planting sit directly over clay drain runs on thousands of properties around Falmouth, Truro and Penzance. Roots do not cause the failure. They find the failure. An RM code almost always sits within a metre of an open joint or a fracture, because that is where the moisture is escaping. Clearing the roots without repairing the joint buys you eighteen months.

Clock References and Distances

Two numbers pin every defect to a precise spot.

The distance is metres from the start node, so “14.2” means the camera had travelled 14.2 metres from the manhole named in the direction field.

The clock reference describes position around the circumference of the pipe, viewed as a clock face. 12 o’clock is the crown (the top). 6 o’clock is the invert (the bottom). A fracture recorded as “10 to 2” runs across the top of the pipe, which is where ground loading from a driveway or an extension shows up first. A defect at 6 o’clock sits in the flow and will catch debris.

What Do Condition Grades 1 to 5 Mean?

Condition grades convert coded observations into a severity score. Grade 1 is a pipe in good condition. Grade 5 is a pipe that has failed or is about to. Reports normally give two separate grades for each pipe run: a structural grade and a service grade. A pipe can score well on one and badly on the other.

Grading is generated using WRc’s Sewerage Risk Management methodology alongside MSCC5, which weights each defect and produces peak and mean scores per run. In practice, the grades read like this:

The trap is the averaged grade. A run of pipe with one Grade 5 fracture at 11 metres and clean pipe either side can still be reported with a low mean structural score. Read the observation log, not the headline grade. One Grade 5 defect is a Grade 5 problem, whatever the average says.

The other trap works the opposite way. A pipe carrying a Grade 4 service score because of heavy grease and settled deposits is a cleaning job, not a repair job. High-Pressure Jetting clears the run and the grade drops to 1. If a contractor quotes you excavation for a service defect, get a second opinion.

Reading the Observation Log, Line by Line

The observation log is where the report either proves its value or falls apart. Each line is one observation, and each observation carries a distance, a code, a clock reference and a grade. Read it as a sentence and it stops being intimidating.

Take a real-world line from a survey on a Victorian terrace:

That reads as: a longitudinal fracture, 12.4 metres downstream of manhole 1, running across the crown of the pipe from the 10 o’clock position to the 2 o’clock position, graded 4, photographed as image 07.

Now cross-reference it. Look at the schematic. If 12.4 metres puts that fracture underneath the rear extension, you have a ground loading failure and a repair that cannot be dug out without lifting a floor slab. That single line has just changed the entire repair strategy, and it is the reason a CCTV Drain Survey is worth paying for before you commit to any drainage work.

Three cross-checks worth making on every report:

• Does every graded defect have a still image? If not, ask for it.
• Does the survey reach the boundary, or does it stop short with an SA code?
• Do the water levels return to normal after each defect, or is water standing throughout the run?

Who Actually Pays for the Defect on Your Report?

Not every defect in a CCTV Drain Survey Report is your financial responsibility. Pipes inside your boundary that serve only your property are private drains and are yours to maintain. Responsibility for private sewers outside the boundaries of private property mostly transferred to sewerage companies from 1 October 2011, and lateral drains beyond your boundary sit with the water company.

For Cornwall properties, that water company is South West Water. The distinction is worth real money:

• A Grade 4 fracture at 6 metres, inside your garden, serving only your house: your cost.
• The same fracture at 22 metres, past the boundary, under the lane: report it to the water company.
• A shared run serving your house and next door: check ownership before you spend anything.

Water companies keep up-to-date maps of the sewers they are responsible for. A good survey report will mark the boundary line on the schematic and tell you which side of it each defect sits on. If yours does not, ask.

Turning the Report Into a Repair Decision

The recommendations section tells you what the engineer thinks. The observation log tells you whether they are right. Match the defect type to the repair method and you will know within a minute whether the quote in front of you is proportionate.

Service defects (roots, grease, deposits, encrustation) are cleared, not rebuilt. Jetting or descaling resolves them. If root mass keeps returning to the same metre marker, the joint underneath it needs repairing, and a repeat blocked drain is the clearest sign of an underlying structural fault.

Isolated structural defects (a single fracture, an open joint, a displaced joint) are candidates for patch repair. A resin patch is installed through an existing access point and cures in place, with no excavation.

Multiple structural defects along one run call for Drain Pipe Relining. A resin liner is drawn through the pipe and cured, forming a new pipe inside the old one. It is a No-Dig Repair, which matters more in Cornwall than almost anywhere else in England. Granite and shillet ground makes excavation slow and expensive. Period properties in Falmouth, Truro and St Ives have narrow access, listed frontages and cobbled lanes that a mini-digger cannot reach. Relining sidesteps all of it.

Collapse (Grade 5, code X) normally means excavation and replacement. There is no liner that fixes a pipe which no longer exists.

Two Cornwall-specific patterns show up in reports here far more often than the national average. The first is infiltration coding (IS, ID, IR) on coastal properties, where a high water table pushes groundwater through open joints and displaced sockets. The second is deformation in pitch fibre pipes, which softens over decades and ovalises under load. Both are structural findings, and both get missed if you read only the summary page.

Rural properties off the mains network need one extra check. If the report ends at a septic tank rather than a sewer, the condition of the pipework feeding that tank affects the tank itself, and Septic Tank Maintenance should be read alongside the drainage findings, not separately.

If the survey was commissioned because you are extending, the report has one more job. South West Water requires notification if you are building over or within 3 metres of a public sewer or lateral drain, and pipe condition forms part of that assessment. Defects found under a proposed extension footprint have to be resolved before you build over them, not after. The building regulations guidance in Approved Document H sets out the wider requirements for drainage and building over sewers.

Get Your Report Explained by the Engineer Who Wrote It

A CCTV Drain Survey Report is only as useful as your ability to act on it. Three things to take away:

• Read the observation log before the summary. One Grade 5 defect is a Grade 5 problem, even if the average grade looks acceptable.
• Separate structural codes from service codes. Structural means repair. Service often means cleaning, at a fraction of the cost.
• Check the boundary before you pay. A defect beyond your property line may not be yours to fix.

At Clear Stream Drainage Solutions, every survey comes with a full coded report, still images, a drainage schematic and a fixed-price quote for any repair identified. No call-out fee. An engineer anywhere in Cornwall within 1 to 2 hours. A 5-year guarantee on every repair we carry out.

Call 01872 222555, or schedule your expert CCTV Drain Survey and get a report you can actually read.

Frequently Asked Questions

What Does Grade 4 Mean on a Drain Survey?

Grade 4 means the pipe is in poor condition with defects that will deteriorate. It is not an emergency, but it does need repair. A Grade 4 structural score commonly points to fractures, broken sections or significant joint displacement, and the standard fix is patch repair or Drain Pipe Relining rather than full excavation.

What Is MSCC Coding on a Drain Survey?

MSCC stands for the Manual of Sewer Condition Classification, the UK national standard for coding drainage defects, published by WRc. The manual is now in its 5th edition and defines the codes used across the industry, including FL for longitudinal fracture and JDM for medium joint displacement. Standard coding means any qualified engineer can interpret any UK report.

How Long Is a CCTV Drain Survey Report Valid For?

There is no legal expiry date on a survey report. For property transactions, most solicitors and lenders expect a report no more than six months old. Drainage condition changes with ground movement, root growth and seasonal water tables, so an older report should be treated as a record of the past rather than the present.

Does a Drain Survey Report Show Who Owns the Drain?

A good report marks the property boundary on the drainage schematic and identifies which defects sit inside it. Drains within your boundary that serve only your property are your responsibility, while lateral drains and public sewers are maintained by the water company. If your report does not show the boundary, ask the surveyor to mark it.

What Does Clock Reference Mean on a Drain Survey?

The clock reference describes where a defect sits around the circumference of the pipe, using a clock face. 12 o’clock is the top of the pipe, 6 o’clock is the bottom. A defect logged as “10 to 2” spans the crown of the pipe, which often indicates ground loading from above.

Can I Get a Drain Survey Report Explained to Me?

Yes. Any reputable drainage company will walk you through the observation log, the still images and the recommendations, and explain the reasoning behind each proposed repair. If a contractor will not explain their own report, that is a reason to get a second opinion before authorising work.