How to Read Your CCTV Drain Survey Report (And What the Codes Mean)

If you have paid for a CCTV drain survey — whether as part of a house purchase, an insurance claim, or an investigation of a recurring problem — the report you receive will be written in a specific coding language called the WRc Manual of Sewer Condition Classification, or MSCC. The current edition is MSCC5. Every competent drainage surveyor in the UK uses it.

That is good news for consistency — two surveys of the same drain should produce the same codes — and bad news for readability. A first-time reader confronted with "F at 4.2m, CR at 6.1m, OJM grade 3 at 8.5m, RH at 11m" has no idea whether their drain is fine or about to fall in.

This guide is what we wish every customer had read before they opened the report. It is not a substitute for the recommendations section written by the surveyor, but it lets you test those recommendations against what the footage actually shows.

What a Proper Survey Report Contains

Before getting to codes, know what you should have received. A report worth paying for will include:

• **A site plan** showing the manholes surveyed, the direction of the survey, and the pipe layout as found.
• **A run-by-run observation log** with chainage (distance from start), code, clock position, and grade.
• **Still images** captured at each observation point.
• **The full video footage** as MP4 or similar, usually linked or on a USB.
• **A written summary** with plain-English findings, severity assessment, and repair recommendations.
• **The surveyor's certification level** — OS19X or OS20X for the camera operator competence scheme.

If your report is a one-page summary with no chainage log and no footage, it is not a compliant WRc survey and you should ask for one. This matters disproportionately when the report is being used for a house purchase negotiation or an insurance claim.

For the wider context of when and why to commission a survey, see our CCTV drain surveys service overview.

The Core MSCC Code Groups

MSCC codes split into structural (pipe condition), service (flow and blockage), and construction (joints and connections). The ones you will see most often on a domestic report are:

Structural Defects

• **CR — Crack.** A visible crack in the pipe wall. Subdivided by direction: CL longitudinal, CC circumferential, CM multiple.
• **F — Fracture.** Cracked through, with visible separation. More serious than CR. Suffixed similarly: FL, FC, FM.
• **B — Broken.** Pipe wall is broken away, with pieces missing or displaced.
• **D — Deformed.** The pipe shape has changed. The percentage is given — DEM 10% means 10% deformation. Common in pitch fibre.
• **DEF — Deformed.** (MSCC5 term, same meaning as D in older reports.)
• **X — Collapsed.** Pipe structure has failed. Urgent.
• **H — Hole.** A hole in the pipe wall, usually with soil or roots visible beyond.

Joint and Connection Defects

• **JDL — Joint Displaced Large.** The joint between two pipe sections has shifted significantly.
• **JDM — Joint Displaced Medium.**
• **JDS — Joint Displaced Small.**
• **OJ — Open Joint.** Gap between pipe sections. Suffixed L, M, S for large, medium, small.
• **OJM — Open Joint Medium.** The single most common defect we find on Merseyside clay drains.
• **CXI — Connection Intruding.** A branch drain that has been drilled or cut through the main in a way that intrudes into the bore.

Service Conditions

• **DE — Deposits.** Silt, grease, or other accumulation. DEC coarse, DEF fine, DEG grease, DES settled.
• **RH — Roots.** Root ingress. Fine, medium, mass, tap. A mass root intrusion RMH is routine on Victorian runs near mature trees.
• **OB — Obstruction.** A non-structural object in the pipe.
• **WL — Water Level.** Recorded as a percentage of pipe diameter. WL 20% is 20% standing water — can indicate a belly or a downstream issue.

Our guide to tree roots in drains in Liverpool covers the RH group in more depth — it is the defect class we see most in mature streets.

Severity Grades 1 to 5

Each structural observation is graded 1 to 5. This is where interpretation lives.

• **Grade 1 — Minor defect.** No action required for many years. Record and monitor.
• **Grade 2 — Minor to moderate.** Plan remedial action within the next 10 years or at next major works.
• **Grade 3 — Moderate.** Remedial action recommended within 5 years. Many insurance-claim defects sit here.
• **Grade 4 — Major.** Remedial action within 1 to 2 years. Active deterioration likely.
• **Grade 5 — Imminent failure.** Action required immediately. Collapse is possible or ongoing.

For a house purchase, grades 4 and 5 are price negotiation material. Grade 3 is worth raising. Grade 1 and 2 defects are the background noise of any Victorian drain and should not derail a purchase.

The overall pipe grade is taken from the worst single defect found. A run with one grade 4 fracture and twenty grade 1 minor cracks is a grade 4 run.

Worked Example: Reading a Line

A line from a report on a drain in Crosby might read:

> 8.5m, OJM, 3 o'clock, grade 3

Translation: 8.5 metres along the surveyed run from the start manhole, there is a medium open joint at the 3-o'clock position on the pipe wall, graded 3 (moderate). That is a joint gap between two clay pipe sections, roughly to the right as the camera travels, and it should be on the 5-year action list.

> 11.0m, RH, 6 o'clock, grade 4

Mass root intrusion at 11 metres, at the base of the pipe, graded major. Active, probably growing, and part of the reason the drain was blocking. Action required within 1 to 2 years.

Red Flags

When reading a report, these findings should produce an immediate conversation with the surveyor:

• **Any grade 5.** This is not a next-year problem.
• **X (collapsed) or B (broken) at any depth.** Urgent.
• **D (deformation) over 10%.** Pitch fibre going oval, reducing capacity, liner may not be possible if it goes much further.
• **H (hole) with visible ground beyond the pipe.** Sand or soil is migrating into the drain; voids may be forming under hard surfaces.
• **"Survey ended at X metres due to water level / collapse / blockage."** The surveyor could not complete the run. That missing section could contain anything.
• **No observations on a long run.** Suspiciously clean. Either the drain is new PVC, or the operator rushed and missed things.
• **Recommendation mismatches the findings.** "Excavation required" for a drain with only OJM defects is usually an upsell. "Jetting and monitor" for an X grade 5 collapse is dangerous.

Recommendations — What Should You See?

The recommendations section should tie each significant defect to a proposed action, with a timeframe. Typical proper recommendations:

• "Patch liner at 6.2m to address grade 4 fracture within 12 months."
• "Full length lining of Run 2 (9 metres) to address multiple grade 3 open joints and root ingress."
• "Excavation at 14m to reinstate collapsed section, chainage 13.5–15m."
• "Jetting and CCTV review in 12 months to monitor grade 2 pitch fibre deformation."

Vague recommendations — "repairs required" with no specifics — are not useful and make it impossible to get second quotes. Ask for specificity.

Our guide on pipe relining vs excavation covers how the repair method is chosen from the survey findings, and the drain repairs service page sets out the range of options available.

Using the Report for a House Purchase

If the survey was commissioned as part of a purchase, the report lives as a negotiation document. The standard approach:

• List grade 3 and above defects with their recommended repair and estimated cost.
• Get a fixed-price quote for that work from a reputable contractor.
• Present the quote to the vendor as a reduction on the asking price, or ask for the work to be completed before exchange.

For the full home-buyer perspective see our CCTV drain survey for home buyers guide.

When to Commission a Second Opinion

If the report you have received recommends substantial work — excavation, full-length lining, anything over about £3,000 — and the contractor who did the survey is also quoting the works, it is reasonable to ask a second contractor to review the footage. At Blocked Drains Liverpool we review third-party CCTV footage at no cost and quote on the findings. It keeps the market honest and makes sure the recommendation matches the defect.

We cover survey and repair work across Merseyside — Liverpool, Wirral, St Helens, Knowsley, and beyond. Call 0333 323 2242 to discuss.