Trenchless

Trenchless Sewer Repair Explained: Lining vs Pipe Bursting

By San Jose Sewer Line Repair · September 6, 2026 · 5 min read

Trenchless is two different jobs that share a word. One puts a new pipe inside your old one. The other destroys your old pipe and pulls a new one through the hole. They cost about the same in San Jose, they both avoid the trench across the driveway and the sidewalk, and they are not interchangeable. Which one fits depends on what the camera finds.

Cured-in-place pipe lining

A tube of felt or fiberglass is saturated with epoxy resin, pulled or inverted into the old pipe through the cleanout or an access pit, and inflated with air or water so it presses against the pipe wall. Then it's cured — hot water, steam or UV light depending on the resin — and hardens into a continuous pipe about a quarter inch thick. Any branch lines that were covered get opened from inside with a robotic cutter.

What you end up with is a jointless pipe with the old clay or cast iron as its outer shell. Roots have no seam to enter. Small offsets are bridged. Cracks are sealed. The bore is slightly smaller than before, which on a four-inch lateral doesn't matter.

Lining is right for:

• Clay with roots at several joints but no collapse
• Cast iron under a slab, where digging means breaking the floor — the standard fix on Eichlers
• Lines under pools, patios, mature trees and anything else you don't want disturbed
• Long hillside laterals in Los Gatos and Saratoga where a trench is impractical

Lining is wrong for a belly, because the liner follows the sag and the low spot stays low. It's wrong for a collapsed section, because the liner needs a pipe to press against. And it's a poor choice for Orangeburg, which is often too deformed to hold a liner's shape.

Pipe bursting

A steel bursting head, shaped like a cone, is attached to a cable run through the old pipe from a pit at the downstream end. A hydraulic puller drags it back through. The head splits the old pipe outward into the surrounding soil and tows a new HDPE pipe behind it — a single length, fused on site, with no joints at all. The new pipe can be the same size as the old one or a size larger.

Bursting is right for:

• Orangeburg in any condition
• Clay or cast iron that's cracked, crushed or too deformed to line
• A line that needs upsizing — a house that added a second unit, say
• Runs where the old pipe's material is unknown or mixed

Bursting is wrong where another utility runs too close to the lateral, because the head displaces soil and can damage a gas or water line beside it. It's wrong for a belly, for the same reason lining is. And it needs a pit at each end, which in San Jose usually means one at the property line or in the street, with the permit and inspection that go with it.

Side by side

What decides it here

The San Jose housing stock leans toward lining. Most laterals are clay that has kept its shape, the failure is roots and offset joints, and a lot of the houses are on slabs. Bursting comes into it for Orangeburg tracts, for cast iron that's rusted through along the bottom, and for the crushed clay we find under driveways where a moving truck parked for a weekend in 1985.

The one situation that turns up constantly and defeats both is the belly — a low spot from a trench that wasn't compacted, or from the ground settling. The Santa Clara Valley lost more than ten feet of elevation to groundwater pumping between 1900 and the 1960s, unevenly, and old laterals didn't all settle at the same rate. A belly gets dug and regraded, and the rest of the line gets lined or burst around it.

What you should see before anyone quotes

A recorded camera run with the distance counter visible, and the contractor pointing at the screen saying which feature makes them prefer one method over the other. If they can't show you why, ask. The trenchless page has the full process, the cost page the ranges, and how lining handles bends and tees goes into what a liner does at each feature in the pipe.