What "trenchless" actually means
Trenchless does not mean no excavation. It means two access pits instead of a trench dug along the entire length of the pipe — one where the work starts, one where it ends, each typically a few feet square.
Everything between those two pits happens underground, without opening up the yard, the driveway, or whatever else sits on top of the line. That's the whole appeal of the method, and the reason the savings show up in restoration rather than in the plumbing work itself.
There are two trenchless methods in common use, plus a third that's really a smaller version of one of them: pipe lining, pipe bursting, and spot lining.
Pipe lining (CIPP)
CIPP stands for cured-in-place pipe. A liner made of flexible fabric, saturated with resin, gets pulled or inverted into the old pipe through an access pit, then expanded against the inside wall and cured — with heat, UV light, or just time — into a new, rigid, seamless pipe sitting inside the old one.
Once it cures, the old pipe is structural only in the sense that it holds the new one in place. The liner is what actually carries the waste from that point on.
This only works if the old pipe can still hold a shape. The liner needs something continuous to press against while it cures. A pipe that has bellied — sagged in the middle under the weight of the soil around it — or one that has partially collapsed usually can't be lined, because there's no continuous host shape left for the liner to take. Those sections get dug up instead.
That's why a camera survey comes before any decision on lining, and why the pipe gets thoroughly cleaned first, usually with a hydro-jet. Roots, grease and scale on the pipe wall keep the liner from bonding properly, and a camera survey run through a dirty pipe will miss problems a clean one would show.
A liner needs a shape to hold while it cures. A pipe that's already lost its shape can't be lined — it has to be dug up.
Pipe bursting
Pipe bursting replaces the pipe instead of relining it. A bursting head gets pulled through the old line from one access pit to the other. As it travels, it fractures the old pipe outward into the surrounding soil while towing a new HDPE pipe in behind it, in the same path.
Because the new pipe is actually new, not a liner riding inside the old one, bursting can fix problems lining can't — a pipe that's badly out of round, has some collapsed sections, or was simply too narrow to begin with, since the new HDPE can be sized up.
It still needs two access pits, and it needs room on at least one end to pull the equipment through. Deep lines, lines running close to other utilities, or runs with a lot of bends can make bursting harder to use than lining.
Spot lining
Not every bad pipe is bad all the way along. Sometimes a camera survey finds one failed joint or one short cracked section in a line that's otherwise sound.
Spot lining repairs just that section — a few feet of liner, cured in place over the bad spot, instead of relining or replacing the whole run. It uses the same resin-and-cure process as full-length CIPP, just scaled down, and it's often the fastest and least invasive option when the rest of the pipe checks out clean.
Trenchless versus digging it up, honestly
Trenchless methods leave the yard, the driveway, the walkway, or whatever else sits above the line mostly untouched, which is the main reason people choose them. Open-cut repair means restoring all of that afterward — regrading, repouring, relandscaping — on top of the plumbing work itself.
Lining does cost you some diameter. The new pipe sits inside the old one, so the inside diameter shrinks by roughly the liner's wall thickness. On a pipe that was already running at its limit, that's worth asking about before choosing lining over bursting or open-cut.
Open-cut is still the right call often enough that we don't try to talk people out of it. A severely bellied line, a pipe collapsed over a long stretch, multiple lateral connections that would complicate a liner or a bursting head, or a line shallow enough that digging barely disturbs anything above it — all of those usually point to just digging it up.
The camera survey is what decides this, not a preference for one method over another. We tell you what the pipe actually looks like and which methods apply to it, and we dig only where the pipe requires it.