Lateral defect map: plot your sewer inspection findings

01 /What does the Lateral Defect Map do?

The Lateral Defect Map draws your sewer inspection as a single horizontal strip, with the access point on the left and the municipal main on the right. Each observation you enter becomes a marker at its distance along the strip, coloured by its concern level and labelled with its depth if you gave one. Below the map, the tool lists the observations sorted by distance, shows the worst concern found, and counts how many findings sit at each level. A print button produces a copy you can file with the video or hand to a contractor.

The point is to see a report as a line rather than a list. Written reports describe findings one at a time; a map shows whether problems cluster in one short stretch, which often suits a single spot repair, or repeat at regular intervals along the run, which usually means the pipe's joints share the same weakness. It also shows at a glance whether the most serious finding sits close to the house or far out toward the street.

02 /What do you need before you start?

You need the written report, ideally the video as well, and five pieces of information. Most come straight from the report header and the observation list.

The twelve observation types are: roots, crack, fracture, offset joint, separated joint, sag or belly, deposits or grease, material change, connection or tap, hole or broken, collapse, and camera stopped. If your report uses codes such as RMJ or JOM, look them up in the inspection report decoder first to find the plain type.

03 /How do you transcribe distances from the footage counter?

Transcribe each distance exactly as the counter or report gives it, measured from the same zero point, and convert feet to metres if needed. Getting this step right is what makes the map line up with the marks on your lawn.

1. Confirm the zero point

   Find where the counter was zeroed: the cleanout opening, the toilet flange or another fixed point. Choose the matching access point in the tool. If the report does not say, ask the operator before relying on the distances.

2. Read the counter at the paused frame

   Use the distance shown on screen when the camera was stopped at the observation, not the distance where the operator started talking about it.

3. Convert feet to metres

   Many counters read in feet. Multiply feet by 0.3048 and round to one decimal place: 27.5 ft becomes 8.4 m, and 60 ft becomes 18.3 m.

4. Handle long defects with two entries

   The tool takes one distance per observation. For a sag or a long run of roots, enter the start distance; if the stretch is long, add a second entry of the same type at its end so the map shows the extent.

5. Prioritise if you have more than 12

   Older clay lines can list roots at many joints. Keep every structural finding and camera stop, then the worst of the repeated maintenance findings.

6. Do not adjust the numbers

   The counter measures cable paid out along the pipe. Do not try to convert it into a ground distance; the tool expects distances along the pipe.

04 /How are concern levels assigned?

Each observation type is assigned one of four concern levels. The assignment is fixed by type, so the same type always gets the same colour on the map.

Camera stopped is rated Act soon for a practical reason: it usually means an obstruction, a deep sag or a collapse, and the pipe beyond it is unknown. A report that ends early has not cleared the rest of the line. Structural failures, holes and collapse, are Urgent because soil can wash into the pipe and a void can form above it.

05 /How do you read the finished map?

Read the finished map for three things: the worst concern and where it sits, whether findings cluster or repeat, and what the depths imply for access. Those three observations turn a list into questions for a contractor.

• Worst concern near the access point — often under the basement slab or just outside the foundation; ask about access from inside versus digging beside the house.
• Worst concern far along the run — may be near or beyond the property line; confirm ownership with your municipality before pricing it. The tool does not know where the line is.
• A tight cluster — several findings within a few metres often point to one disturbed area, such as an old repair, a tree or a service trench, and may suit one spot repair.
• Evenly spaced Plan markers — roots or offsets at regular intervals track the joints of the pipe and suggest a whole-line approach such as lining, not one repair.
• Depth labels — deeper marks usually mean larger excavations; shallow marks under hard surfaces bring their own costs.
• A camera stop before the main — treat everything to the right of it as unknown until a second pass is done.

Measure distances on the ground from the access point along the pipe's route, not in a straight line, when you compare the map with paint marks. The locate marks from the inspection are the reliable ground positions; sewer line locating and depth explains how they are made.

06 /What are the limits of the Lateral Defect Map?

The map is an organising tool. It shows what you enter and nothing more, and it should never be the only basis for a repair decision.

• It does not watch your video or check the report; its accuracy depends on your transcription.
• Concern levels come from the type of observation only, not its size, length, number or trend.
• Distances follow the pipe from the access point; they are not straight-line distances across the yard.
• It does not know where the property line is or who owns any section of pipe.
• Depths are only the figures you enter from the operator's locates.
• It gives no prices, repair methods or quotes.
• It holds up to 12 observations per map.

Once your map is printed, the decision path for each finding is in after the inspection: what next, and what each defect means physically is in common sewer defects explained. If you need an inspection, a second pass or a second opinion, request a quote.

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