Under the slab
Under-slab sewer repair in San Diego
Clairemont, Allied Gardens, Serra Mesa, the flat parts of La Mesa and Chula Vista: post-war ranch houses on a concrete slab, with cast iron drain lines cast into the ground underneath. Sixty years on, the bottoms of those pipes are rusting through, and the fix is a different job from a yard lateral.
How you find out
A slow kitchen sink that a cable fixes for a month. A wet spot on the slab in the hall, or warm flooring where a hot water line and a drain line share the same trench. A smell in one bathroom that comes and goes. Cockroaches or drain flies from a floor drain. Or nothing at all until a camera inspection before a remodel finds that the last 30 feet of pipe under the house has no bottom.
Cast iron corrodes from the inside, on the floor of the pipe where the water sits. The top of the pipe looks fine on a camera for years after the bottom has opened up. Once it does, wastewater soaks into the soil under the slab, and in expansive clay that means the ground swells. Heaved tile, a door that sticks in winter, and a foundation contractor in the conversation.
Three ways to fix it
Lining in place. If the pipe is still round enough to hold a liner, we clean it, descale it and install a CIPP liner from a cleanout or a pulled fixture, with the branch connections reinstated by a robotic cutter. No concrete cut at all in most cases. This is the first thing we look at for every under-slab line, because it's the least disruptive and the trenchless methods we use in the yard work just as well under a house.
Tunneling. A crew hand-digs a tunnel from outside the foundation, under the footing, along the pipe. The old pipe is replaced with ABS in the tunnel and the soil is packed back. Nothing inside the house is touched. Slower and priced per foot of tunnel, but it keeps the floors intact, which matters when the floors are original oak or the kitchen was just done.
Cutting the slab. Saw-cut the concrete over the pipe, dig, replace the pipe, backfill, pour. Cheapest per foot and the right call when the floor is coming up anyway for a remodel, or when the failed section is short and in a garage or utility room.
Re-routing overhead is the fourth option on some houses: abandoning the under-slab line and running new drains through the attic or along an exterior wall to a new connection. It works for a bathroom on an outside wall and not much else, and we'll say when it's the cheaper path.
What it costs
| Method | Typical San Diego range |
|---|---|
| CIPP lining under the slab, per foot | $150 – $300 |
| Tunneling, per foot | $250 – $450 |
| Slab cut and replace, short section | $3,000 – $8,000 |
| Full under-slab re-pipe, 3-bed ranch | $12,000 – $30,000 |
A single failed run under a kitchen is often $4,000–$9,000. A whole-house under-slab job on a 1955 Clairemont ranch, all the cast iron gone, is the top of that table, and it's the job where the difference between lining and cutting the floor is the whole cost of a new kitchen floor. The cost page sets these next to the yard-lateral prices.
Under-slab and the lateral together
The lateral from the house to the street is usually the same age as the pipe under the slab. We camera both on the same visit. Replacing one and leaving the other is the most common way to pay for the same problem twice, and we'd rather show you the whole picture and let you phase it than sell you half. Sewer line replacement covers the outside half.
The foundation question
If the slab has already heaved or cracked, we'll tell you what we see, and if it needs a foundation contractor we'll say so. What we won't do is line a pipe under a slab that's actively moving without a conversation about why; the ground under it is wet for a reason, and the leak is often the reason. Drought, soil shrink and pipe breaks explains how San Diego's clay does this to a slab.
Other sewer services
Sewer Line Repair
Backups cleared, roots cut, the line hydro jetted and cameraed, and a spot repair where one section is broken and the rest is sound.
Sewer Line Repair →Sewer Line Replacement
A new lateral from the house to the main when the old cast iron or clay is done. Open-trench where it makes sense, trenchless where it doesn't.
Sewer Line Replacement →Trenchless Sewer Repair
Pipe lining and pipe bursting through one or two small pits, so the driveway, the patio and the city sidewalk stay where they are.
Trenchless Sewer Repair →Sewer Camera Inspection
A recorded camera run from the cleanout to the main, with the break located from the surface. The basis for every honest quote, and the first thing to do before buying an old house.
Sewer Camera Inspection →Questions we get asked
How do you know the leak is under the slab?
A camera inspection with a sonde locate. We run the camera to the bad section and trace the sonde from above so we can mark the spot on the floor and read the depth. Where the camera can't get through, a hydrostatic test of the under-slab system, plugging the line and watching the water level, confirms whether it's holding.
Will you have to break up my floors?
Often not. Lining runs from a fixture or cleanout and needs no concrete cut. Tunneling reaches the pipe from outside the foundation. We cut the slab when the failed section is short and the floor is cheap or coming up anyway. The camera footage decides, and we'll show you where each option lands on the quote.
Does homeowners insurance cover an under-slab sewer leak?
Sometimes partly. Most California policies exclude the pipe itself and the cost of fixing it, but may cover access, the concrete and floor damage, and water damage inside. A service line endorsement covers more. Read the policy before you assume either way; sewer line insurance is one of the things we cover on the rental-property page.
Need sewer line work in San Diego?
Call for a free estimate. Mon–Sat 7am–7pm.