A new sewer pipe, built inside the old one.
Lining puts a jointless pipe inside a cracked or root-filled sewer line, working through an opening that is already there. The trees, the lawn and the drive stay as they are. When a pipe has collapsed or sags, lining can't fix it, and digging is the right answer.
How a pipe is lined
Seven steps. Pick any one to see it again.
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Inspect
A camera goes in through a cleanout and records the whole run. The video shows where the roots, cracks and offset joints are, how long the run is, and whether the pipe is still round enough to line.
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Clean
Roots and scale are cut out and the line is flushed. A liner seals against a clean wall, so this step decides how good the result is.
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Wet out
Above ground, a felt or fiberglass tube cut to the measured length is soaked through with resin.
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Install
The tube goes in through the cleanout. If there isn't one, a cleanout is put in or a small access pit is dug. For a full run the tube is turned inside out into the pipe by air or water pressure, up to about 150 feet in one piece. A short section is pulled into place and inflated instead. Either way it ends up pressed against the old wall.
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Cure
The resin is hardened in place with hot water, steam or UV light, or left to cure on its own. The method is picked for the job: pipe size, length, and how soon the water has to be back on. Once it sets, the old pipe holds a second, seamless one.
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Reopen
Any branch line the liner covered is cut open again from inside with a robotic cutter, so nothing has to be dug up to reconnect it. Where a branch joins the line, a short connection liner can seal the joint.
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Check
A second camera run shows the liner tight to the wall and the branches open. Ask for that video. It is the record of what you paid for.
Lining or digging
The camera video decides it. These are the usual answers.
| What the camera shows | Lining | Digging |
|---|---|---|
| Cracks, or roots at the joints, and the pipe still round | Fits | Works, and opens the ground above the whole run |
| The run passes beneath a finished basement, a patio, old trees or the street | Fits, through a cleanout or one small opening | Means breaking out and putting back what is on top |
| A section has collapsed | Not until that section is dug and replaced | Fits |
| A sag (belly) that holds water | No. The liner follows the sag. | Fits |
Who calls about lining
- Older houses
- Cast iron and clay under finished basements, old trees and long drives.
- Apartment buildings
- Shared lines, and tenants who can't be without water for long.
- Restaurants and storefronts
- Grease-heavy lines, and a business that can't close for a week.
- Churches and schools
- Long runs under old buildings, and short windows in the calendar.
- Condo and HOA buildings
- Shared lines, and a board that has to decide who pays.
- Hotels and high-rises
- Cast iron stacks behind finished walls on every floor.
How old the pipe under your town is
A house's sewer line is usually as old as the house. Where most homes went up before 1960, most laterals are clay or cast iron that has been in the ground for 65 years or more.
| Town | Before 1940 | Before 1960 | Median year built |
|---|---|---|---|
| City of St. Louis | 58% | 75% | 1938 |
| University City | 38% | 72% | 1949 |
| Webster Groves | 35% | 68% | 1952 |
| Richmond Heights | 43% | 66% | 1947 |
| Ladue | 21% | 64% | 1955 |
| Clayton | 35% | 57% | 1954 |
| Kirkwood | 17% | 47% | 1962 |
Source: U.S. Census Bureau, American Community Survey 5-year estimates, 2020-2024, tables B25034 and B25035. Estimates, with margins of error.