Cast iron pipe replacement: $150 to $250 a foot (Angi 2026)

National figures. Where the pipe runs (under a slab, in a crawl space, in a wall) matters more than the pipe itself.

Do this now: an old cast iron drain that is backing up or smelling

Cast iron drains fail slowly, so the first steps are about not making it worse and getting a look inside:

1. Backing up? Stop all water use; HomeGuide says several drains backing up at once is a main line sign. Keep children and pets away from any sewage; the Connecticut health department says it carries bacteria, viruses and other germs.
2. No chemical drain cleaner. HomeGuide says it may eat through the pipe, and old cast iron is already thin. MedlinePlus says drain openers can burn skin and eyes.
3. Look low. HomeGuide's drain pipe signs: puddles in a basement or crawl space, wet spots or mold on floors or walls, odors, slow fixtures, gurgling when toilets flush, a higher water bill.
4. Get the camera first. Angi prices a camera inspection of a cast iron line at $250 to $400; HomeGuide at $125 to $500. It shows whether the pipe can be lined or has to come out.
5. Call the plumber line. Ask for the camera priced, the video, and lining, bursting and dig-and-replace each priced per foot.

Is it an emergency? When a cast iron drain cannot wait

A cast iron drain is an emergency when sewage is in the house, and Angi's 2026 emergency guide prices an after-hours main sewer line clog at $1,325 to $5,000; a planned replacement is $150 to $250 per foot.

• Call now: sewage in a tub, shower or floor drain, or water rising in the tub when a toilet flushes. See emergency plumber and sewage cleanup.
• This week: the same clog back within weeks of a snaking, gurgling in several drains, or a sewer smell indoors. See toilet gurgling for the checks.
• Plan it: a camera that shows rust and corrosion, cracks or offset joints (HomeGuide's camera guide). Angi says to replace rather than repair when pipes are corroded throughout, clog often or are outdated materials such as old cast iron.

How much does cast iron pipe replacement cost?

Cast iron drain pipe replacement costs $150 to $250 per linear foot installed in Angi's July 2026 guide and HomeGuide's February 2026 guide, and Angi puts a standard home's drain pipe replacement at $225 to $1,169 with a $696 average.

The pipe is a small part of that. Angi lists cast iron at $5 to $20 a foot for materials, HomeGuide at $5 to $12, and PVC at $0.50 to $8 (Angi) or $0.50 to $5 (HomeGuide), which is why cast iron is replaced with plastic rather than more iron. Angi's sewer pipe guide lists a cast iron sewer line replacement at about $50 per foot and PVC at $4.50 per foot for the pipe. Plumbers charge $45 to $200 an hour (Angi), with a $150 to $300 minimum fee; permits are $100 to $500 (Angi).

Drain pipe repair and replacement by location. Both guides say pipe under a foundation takes the most labor and equipment.

• Under a slab: HomeAdvisor's sewer guide adds $300 to $350 per foot for a line under a slab. Concrete, then flooring at $4 to $15 per square foot (HomeGuide), comes after the pipe. See slab leak repair.
• In a wall: drywall repair is $300 to $1,500 or more (HomeGuide). Angi prices a plumbing stack replacement at $1,500 to $4,000 in its pipe leak guide.
• Whole house: neither guide gives a whole-house drain total; ask for feet and a per-foot price by location.

How long do cast iron pipes last?

Cast iron pipe lasts 100 years in Angi's sewer pipe guide, 50 to 100 years in HomeGuide's and 75 to 100 years with proper care in This Old House's, and Angi says it fell out of favor when PVC arrived in the 1960s.

Published lifespans by pipe material. Soil, roots, water chemistry and how the line was installed move these either way.

• A house built before the mid-1960s with original drains is at or past the low end of every published range.
• Angi says cast iron deteriorates, corrodes and is more likely to clog than PVC, and may crack if exposed to high heat.
• HomeGuide's camera guide says roots through hairline cracks are common in older cast iron and clay and less common in PVC.
• HomeGuide's jetting guide says cast iron handles hydro jetting well, but pipes over 40 years old or deteriorated may not be suitable, so a camera look comes first; see hydro jetting cost.

Signs a cast iron drain pipe is failing

Neither cost guide has a cast iron specific list, so the signs are the general drain pipe signs on a house old enough to have it: Angi says to watch for slow drains, bad odors and water stains.

• HomeGuide's broken drain signs: water damage; puddles in a basement or crawl space; foul odors or sewage backup; clogged or slow fixtures; wet spots or mold on floors or walls; gurgling when toilets flush; higher water bills.
• Angi's replace-not-repair test: corroded throughout, frequent clogs, or an outdated material such as galvanized steel or old cast iron.
• What the camera shows: HomeGuide's camera guide lists cracks, rust and corrosion, offset joints, bellies, roots and collapse. See sewer camera inspection.

Cast iron sewer line replacement: trenchless options

Relining a cast iron sewer line costs $90 to $250 per foot and pipe bursting $60 to $200 per foot in HomeGuide's sewer guide, against $50 to $250 per foot to dig and replace, so trenchless is often the cheaper way to put the yard back.

• Cured-in-place lining (CIPP): a resin liner set inside the old pipe. HomeAdvisor says it needs one excavation point. It suits cast iron that is corroded but still round.
• Pipe bursting: HomeAdvisor says a pneumatic or hydraulic head breaks the old pipe apart while a new one is pulled through. It replaces the pipe rather than lining it.
• Spin-casting: HomeGuide lists it at $80 to $250 per foot.
• When trenchless will not work: HomeAdvisor says only if the pipe has not completely collapsed. A collapsed or badly deformed section is a dig.
• Full per-foot comparisons, what digging adds, and the insurance side are on sewer line replacement cost; spot repairs and who pays for the lateral are on sewer line repair.

Orangeburg pipe replacement cost

Orangeburg pipe is replaced at the same sewer line rates, $50 to $250 per foot in HomeGuide's guide, because no publisher we checked prices it separately; what sets it apart is that it lasts 30 to 60 years (HomeGuide) and Angi says it carries a high risk of collapse.

• What it is: Angi says Orangeburg was popular for several decades after World War II and was expected to last a lifetime, but the pipes easily degrade and deform over time and are vulnerable to roots. This Old House says PVC has largely replaced it because it deteriorated.
• Camera first: Angi prices a camera inspection of an Orangeburg line at $400 to $800, the top of its range, because the pipe is fragile and often deformed.
• Lining is often out. HomeGuide's jetting guide says older clay or Orangeburg is more vulnerable to damage from jetting, and a deformed pipe is not round enough to line. Expect a bursting or dig quote.
• Typical total: HomeGuide puts a 40 foot sewer line replacement at $2,000 to $10,000 with a $6,000 average; This Old House's average full replacement is $3,320.

Questions to ask before you replace cast iron pipe

• Can I see the camera video, with footage from the cleanout?
• Line it, burst it or dig, and why? And what each costs per foot.
• How many feet are cast iron, and how many are under the slab?
• Is concrete, flooring or drywall repair in the price?
• What is the warranty on the liner or pipe and on the labor? In writing.
• License number and proof of insurance. Ask for the plumber's license number and proof of insurance yourself; the plumbing license table shows who licenses plumbers in six states.

Supply pipes in the same old house are a different job: repiping cost covers galvanized and polybutylene. A clog that keeps coming back: drain cleaning.

More plumbing prices: how much a plumber costs, emergency plumber and home repair costs. Calls go to an independent company that serves your area and takes this kind of job; hours vary. How calls work.