Lining or pipe bursting: which trenchless method fits my sewer?

Two very different ideas

Both methods avoid a trench along the run, and that is where the similarity ends. Cured-in-place pipe (CIPP) lining keeps the old pipe and builds a new one inside it. Pipe bursting destroys the old pipe and drags a new one into the space it occupied. Which is right depends almost entirely on the condition and material of what is already in the ground — which is why the decision starts with footage, not a sales pitch.

How lining works

1. The line is cleaned and, if needed, descaled, and any protruding roots or offsets are cut back.
2. A felt or fibreglass sleeve saturated with resin is pulled or inverted into the pipe from a cleanout or access pit.
3. The sleeve is inflated against the host pipe and cured — with hot water, steam, or ultraviolet light — into a hard, continuous pipe.
4. Branch connections are reopened from inside with a robotic cutter; a final camera pass documents the result.

The liner needs the host to hold its shape while it cures, so the host must be round and continuous. Clay with joint problems, concrete with a rough crown, and scaled cast iron under a slab are all good hosts. See sewer lining for how we do it.

How bursting works

1. A pit is dug at each end of the run — typically at the house and near the property line or the main.
2. A cable is fed through the old pipe from one pit to the other.
3. A bursting head, larger than the old pipe, is pulled through by a hydraulic winch. It splits the old pipe and pushes the fragments into the surrounding soil.
4. New HDPE pipe, fused into one jointless length, follows the head and is connected at each end.

Because the old pipe is broken apart, bursting can work where it is collapsed, ovalised, or in pieces, as long as a cable can pass and the route allows it. See pipe bursting.

Choosing between them

The combinations that come up most

Real lines are rarely one condition end to end. The most common Seattle plan is a small excavation to fix one thing a liner cannot handle — a dropped section, a belly, a severe offset — followed by a liner through the rest. The second most common is bursting the yard section while lining the under-slab section, because the two pipes fail differently. Neither combination is exotic; both are a matter of matching the method to what each stretch of footage shows, which is why we quote from the video rather than from the curb.

What both need before they start

A clean line, a full-length trace with depths, a side sewer permit from Seattle Public Utilities for the yard work, and a candid conversation about what the footage shows. If a contractor recommends one method without having run a camera, or recommends the only method they own for every line, that is worth noticing. The questions to ask article has the list.