A flood does several things to a sewer lateral at once. The main surcharges and pushes sewage back up the lateral into the house. Floodwater full of silt and debris enters through every open joint, every cleanout cap that floated off and every fixture that overflowed, and leaves a bed of sediment the length of the line. Saturated ground loses its strength, bedding washes out and shallow pipe can float or settle. And the stormwater connections that were tolerable in ordinary rain become the route by which the flood entered. When the water goes down, the drain system is in an unknown state, and a camera inspection before anyone relies on it again is the sensible first step.
Quick answer: after a flood, inspect the lateral and the building drain for silt and debris beds, for joints that opened as the ground moved, for bellies where bedding washed out, for a backwater valve held open by debris, and for the stormwater connections that let the flood in. Clear the silt first, because a camera cannot inspect under it; then inspect the structure; then address the connections and the valve. A lateral that was sound before the flood is usually sound after it, once cleaned, but the ground around it may not be.
Silt and debris
Floodwater carries fine sediment, and a lateral that was full of it for days has a bed along its whole length, deepest in bellies and at the connection to the main. The camera shows a pale or grey bed covering the invert, often with debris, leaves and gravel in it, and the picture may be murky from suspended silt that has not settled. The bed hides joints and defects, so the structural inspection waits until the line is jetted. The depth of the bed and the distance where it is deepest are the jetting contractor’s specification. The sediment guide covers reading it, and cleaning before inspection the sequence.
Ground movement
Saturated soil flows, and a lateral in it can settle, float if it was empty, or lose the bedding beside it as water moves through the trench. The camera after cleaning shows new offsets and separations, bellies that were not there before, and in rigid pipe circumferential cracks near joints. Compare with any previous footage; a defect that was not in last year’s recording is flood damage, and the distinction matters for an insurance claim. The settlement guide describes the findings.
Surcharge damage
A surcharged main pushes sewage up the lateral under pressure. Joints that were merely open now leak outward under head, cleanout caps lift, and a backwater valve, if there is one, takes the full force. The camera checks the valve, which is often found held open by a wad of flood debris, and the joints nearest the main for signs of outward flow: scour marks and washed bedding. The backwater valve guide covers the valve inspection, which in a flood case is done at the access cover as well as by camera.
How the flood got in
If the basement flooded with sewage rather than groundwater, the sewer was the route, and the question is whether a backwater valve would have stopped it or whether a stormwater connection overwhelmed the lateral. A camera in the lateral during the next heavy rain shows any side entry carrying clear water. A house that flooded through the floor drain without a valve needs one; a house with a sump or downspout tied into the lateral needs it disconnected. The stormwater connection guide covers the disconnection.
Order of work
First, confirm the lateral drains at all; a camera from the cleanout establishes whether it is open. Second, jet the silt out. Third, inspect the structure with the camera and compare against any earlier footage. Fourth, check the backwater valve at its cover and clear it. Fifth, identify and disconnect stormwater connections. Sixth, repair what the flood broke. The camera is used at the first, third and fifth steps, and its footage is the record for the insurer at every step. Inspection after a basement flood covers the house side, and hurricane and flood recovery the regional scale.
Safety
Floodwater in a sewer is sewage, and a flooded basement is a confined space with sewer gas in it. Ventilate, wear protection, and do not enter a basement with standing water until the power is confirmed off. The camera equipment comes out of the job contaminated and is cleaned before it goes in the van. Hygiene after sewer camera work covers the cleaning.
What to record
Whether the line drained before cleaning. The silt bed’s depth and extent. Every structural finding with its distance, and whether it appears in earlier footage. The backwater valve’s condition. Any stormwater connection found. Dated footage from each stage. That record is the insurance claim, the repair specification and the baseline for the next flood.
Common questions
Should I inspect the sewer after a flood?
Yes, before relying on it. Silt, moved joints, a jammed backwater valve and the route the flood took are all findings the camera makes.
Can the camera inspect a silted line?
It can confirm the line is open and show the bed. The structural inspection waits until the silt is jetted out.
Did the flood break my sewer?
Compare with earlier footage. New offsets, bellies or cracks are flood damage; old ones are not.
Related guides
See storm drain inspection after flooding, infiltration on camera, and the best sewer cameras for restoration work.