How trenchless sewer replacement works, from camera to final video

01 /What does trenchless actually mean?

Trenchless means the pipe is renewed without digging along its whole length. The work is done from the ends, through an existing cleanout, a small pit, or both. The surface between the access points stays largely untouched, which is why the method is popular where a driveway, mature tree, deck or finished landscape sits over the line.

Two families do most residential work. Lining leaves the old pipe in place and cures a new structural pipe inside it. Bursting destroys the old pipe and replaces it with a new one along the same path. They share a workflow but differ in what they need from the site and the old pipe, which the table below summarises.

02 /What happens before any trenchless work starts?

Before installation, the crew needs to know the exact length, diameter, depth, material changes and connections of the line. That comes from a camera inspection with a distance counter and a sonde locate marked on the surface.

1. Camera and measure

   A push camera records the whole line from the access point to the main, with distances. The crew notes every diameter change, bend, branch connection and defect, because each one affects liner sizing or pit locations.

2. Locate and mark

   A sonde in the camera head is traced from the surface to mark the route and depth at key points. For bursting, these marks set where the pits will go.

3. Public utility locates

   Before any pit is dug, gas, electric, telecom and water lines are located through the provincial one-call service, such as Utility Safety Partners in Alberta and British Columbia or Ontario One Call. Private lines on your property may need a private locator.

4. Permits

   Most municipalities treat sewer renewal as plumbing work requiring a permit and, often, an inspection. Work in a boulevard or road needs separate permission. Confirm the requirements with your municipality.

5. Plan the no-water window

   The line cannot take flow during installation. Agree on the hours when nobody in the house uses water, and whether a temporary bypass is needed for a multi-unit building.

03 /How is the old pipe prepared?

The old pipe is cleaned back to its wall. For lining, this is the step that most determines quality: the liner will bond to, and take the shape of, whatever surface it is cured against. Roots left in a joint become a lump in the liner, and loose scale can stop the liner from seating.

• Clay and concrete lines usually need mechanical root cutting and hydro jetting to remove roots and debris from every joint.
• Cast iron usually needs descaling with chain knockers or abrasive cutters to remove tuberculation until the original bore is recovered. SewerJetting.ca covers prep jetting in more depth.
• Offsets and protruding taps may need grinding back so the liner can pass and seat.
• A second camera run after cleaning confirms the pipe is ready and often reveals defects that roots or scale were hiding.

For bursting, cleaning matters less because the old pipe is destroyed, but the crew still needs a clear path for the cable or rods. A camera run confirms the route, and a collapsed section may need a small dig so the cable can be threaded through.

04 /How is a liner installed and cured?

A liner is a tube of felt or glass-fibre fabric saturated with resin on site or at a shop, a step called wet-out. It is then placed in the host pipe either by inversion or by pulling it in place.

1. Inversion: the liner is turned inside out into the pipe with air or water pressure from an inversion drum. The resin face ends up against the host wall.
2. Pull-in-place: the liner is winched into position and then inflated with a separate bladder or calibration tube.
3. Curing: depending on the resin system, the liner is left to harden at ground temperature or is sped up with circulated hot water, steam or an ultraviolet light train. Pressure is held until cure is complete.
4. Finishing the ends: the liner is trimmed at the access points and the ends are sealed to the host so water cannot travel between the two.
5. Reinstatement: a robotic cutter travels inside the new liner and reopens each branch connection that the liner covered.

Resin choice, liner thickness and curing method are engineering decisions, and they affect how the finished pipe performs. CIPP lining explained goes through them in detail, including how much bore the liner costs you.

05 /How does a bursting installation proceed?

Bursting starts with two pits, one at each end of the section being replaced. A cable or a string of rods is fed through the old pipe from the receiving pit to the launch pit and attached to a bursting head. The new pipe, fused into a continuous length above ground, is attached behind the head.

As the head is pulled, its expander breaks the old pipe outward and compresses the fragments into the surrounding soil, making room for the new pipe. Static systems use a hydraulic unit to pull or push steadily. Pneumatic systems add a percussive hammer inside the head to help break stubborn material. Once the new pipe arrives in the receiving pit, it is left to relax briefly, then connected at both ends, and each branch connection along the route is excavated and joined. Pipe bursting explained covers heave, upsizing and nearby utilities.

06 /What equipment does trenchless pipe replacement use?

Trenchless work is equipment-heavy, which is part of why a small job still carries a meaningful setup cost. Knowing the equipment helps you ask whether a contractor actually owns the tools for the method they are proposing.

07 /What can trenchless not do?

Trenchless methods cannot change the path or slope of the line. Both follow the existing pipe, so a belly holding water, a line that runs under an addition you want to move, or a route that needs to avoid a new foundation all need an open-cut section or a new bored path. Neither method can pass a collapse that the crew cannot get a cable or camera through without a dig.

• Sags: lining copies the dip exactly; bursting follows it. See can trenchless fix a belly.
• Severe deformation: a flattened fibre pipe or crushed section may not hold a liner in round.
• Many connections: each one needs a reinstatement (lining) or a pit (bursting), which erodes the trenchless advantage.
• Tight bends: lining can negotiate some bends with the right liner; bursting handles bends poorly.

If you are weighing these limits for your own line, the Replacement Method Selector rates lining, bursting, open cut and spot repair against your depth, surface, condition, access, bends and connections.

08 /How do you know the job was done properly?

You know from a recorded video of the finished pipe, taken from the same access point as the original inspection so the distances line up. Watch it, or have someone independent watch it, before the final payment.

• The pipe is continuous from the access point to the main with no gaps, holes or visible joints in a liner.
• Branch connections are fully reopened with smooth edges, not partly covered.
• Wrinkles or folds in a liner are minor and do not catch debris.
• There is no standing water beyond what the original grade would explain.
• Burst pipe arrives at both ends without visible damage and is properly joined.

Keep that video with the permit, the invoice and the written warranty. Sewer replacement warranties and final checks lists what to ask for, and when you are ready to price the work, request quotes with your footage attached.

FAQQuestions people ask