Do you want to know how to repair cast-iron pipe? Does every solution you found so far involve tearing up floors, destroying driveways, or trenching through your yard? This article will set you up with how to repair cast iron pipe with little to no damage. First, you learn how to identify the signs you need repair, followed by how cast iron pipes used to be repaired, and how plumbers fix them today.

Signs You Might Need Cast Iron Pipe Repair

Most homes built before the 1970s are equipped with cast iron pipe. Their blackish-brown color and hard material help identify them. Cast-iron drain pipes are strong, but nature has a way of breaking things down over time. They are supposed to have a life-use of around 50 to 100 years, but unavoidable circumstances affect the material’s longevity. Signs you might have a problem include,

Constant Backups
If you have backups in all of your toilets, sinks, and showers, the cast iron sewer pipe (which connects all of them) is probably faulty.

Sewer Odor
If you can smell sewage in your house, you can be confident that your cast iron pipe is damaged. That foul smell will ruin your home’s ambiance.

Slow Drains
A slow drain is a clear sign that something is wrong with your cast iron pipe. We can determine if the problem is just a blockage or actual damage to the pipe with a simple CCTV sewer camera inspection.

How To Repair Cast Iron Pipe

Unnatural Yard Growth
If sewage is leaking from a pipe into your yard, you are going to see a few telltale signs. For one, the grass in certain areas will seem suspiciously luscious. Sewage acts as a fertilizer for your grass, making it grow faster in affected areas. You may also notice dips and valleys forming due to the soil dissipating under the grass.

Foundation Issues
When a drain pipe leaks sewage, the excess water will cause the soil to expand and shrink (if the foundation was built on top of expansive soil) causing your foundation to shift.

How To Repair Cast Iron Pipe

Insects or Rodents
If a drain pipe is damaged, rats, mice, sewer flies, cockroaches, or palmetto bugs can enter your home. Calling pest control may eliminate the current invaders, but the pipe is still cracked, and they will come back.

Tree Roots
Older trees on your property are bound to have long, invasive roots. They seek out nutrients, sensing pipes flowing with waste or water. The roots attack the joints where the lines are their weakest. Once they’re inside, they drink and drink until the roots clog up your pipes.

Check out more about: How to remove tree roots using hydro-jetting

How To Repair Cast Iron Pipe

How They Used To Repair Cast Iron Drain Pipes

Not so long ago, cast iron pipes, and all sewer lines, for that matter, were repaired using tedious and destructive methods. If builders laid a pipe underneath concrete, it had to be chipped away with jackhammers or picks. If your line ran under your driveway, that would mean pavement, asphalt, or brick had to be broken apart.

Let’s not forget inside your kitchen or bedroom. Now you’re looking at wood flooring being torn up, tile cracked open, and carpet being ripped out of your home.

How To Repair Cast Iron Pipe

How To Repair Cast Iron Pipe With Minimal Damage

Pipe Lining (Trenchless)

A unique, epoxy-impregnated liner is inserted into the old pipe, inflates, and creates a new pipe structure directly inside the old one. Pipe lining can be considered replacement or repair depending on whether the whole pipe length will be lined or just a section.

If only a section of pipe (aka a spot repair) is lined, it is considered a repair. If you line the whole pipe from start to finish, it is basically like getting a brand new pipe installed (aka replacement).

Pipe Lining

Pipe Bursting (Trenchless)

Pipe bursting is where a new HDPE (high-density polyethylene) pipe is attached to a winch with a cone-shaped bursting head and pulled through the damaged line. The damaged pipe breaks apart as the new one takes its place.

Note: Sometimes, a drain pipe is so severely damaged that no trenchless method is viable. Plumbers cannot use trenchless technology on pipes that are back-pitched, which means that the original contractors failed to use the proper slope for your sewer line to your city connection. If the pipe has collapsed onto itself, you will have to go the conventional trenching route.

Read also: How to repair a sewer drain

Pipe Bursting

Cost

Trenchless sewer repair can cost anywhere between $4,000-$15,000 for the average single-family home. Jobs range from a few feet of repair to hundreds of feet, changing the pricing per amount of needed work. There will always be a base cost starting at permits, contractor mobilization, project minimums, and then prices move on from there.

Conventional sewer repair, on average, costs $50 to $450 per linear foot. The price to install brand new pipes throughout your home or yard could run to $15,000 because of all the extensive work, such as trenching and excavation. Conventional sewer repair quotes will be lower than trenchless, but they don’t include the cost to clean up the mess and repair the property damage.

Who Can Repair Cast Iron Pipe Near You

If you suspect damage in your cast iron pipes, it’s best to call a professional plumber who specializes in trenchless sewer repair. These experts can inspect your lines with a CCTV sewer camera, locate the problem without digging, and recommend the most effective repair method.

For reliable, minimally invasive solutions, many homeowners trust New Flow Plumbing. They provide free sewer inspections, detailed repair estimates, and advanced options like pipe lining and pipe bursting to restore your plumbing system without tearing up floors or landscaping. Whatever the issue, New Flow Plumbing can quickly get your sewer lines running smoothly again.

FAQs

You can repair cast iron pipes without welding by using trenchless methods like pipe lining or pipe bursting. These techniques create a new, durable pipe inside or in place of the old one without digging or welding. Pipe lining uses a resin-coated liner that hardens to form a new pipe, while pipe bursting pulls a new pipe through the old one as it breaks apart. Both methods cause minimal damage to floors and landscaping and are commonly used by specialists such as New Flow Plumbing for long-lasting results.

A temporary fix for a hole in a cast iron pipe can be done using:
Epoxy putty – Mold it over the hole and let it harden. It seals leaks for a short period.
Pipe repair clamp – A metal sleeve tightened over the hole to stop leaks under pressure.
Rubber patch and hose clamp – Wrap a piece of rubber around the hole and secure it tightly.
These are only short-term fixes to stop leaks until a plumber can do a proper repair. For a lasting solution, a trenchless repair or section replacement is best.

To repair a cracked downpipe, start by cleaning the surface and removing any rust or loose debris. Then apply epoxy putty or a cast iron pipe repair kit directly over the crack. For larger cracks or severe corrosion, the damaged section should be replaced or relined using a trenchless method like pipe lining, which forms a new inner wall without replacing the entire pipe. New Flow Plumbing often uses this approach to restore pipes quickly and without major demolition.

The best sealant for small leaks in cast iron pipes is epoxy putty or a two-part epoxy compound designed for metal repair. These products bond tightly to cast iron, sealing cracks and holes. For joints or larger areas, pipe joint sealant or rubber sleeve clamps can also help. However, sealants are temporary; if you have ongoing leaks or corrosion, it’s better to schedule a professional inspection.

The most reliable epoxy types for cast iron repair are metal-reinforced epoxies like JB Weld, Loctite Metal and Concrete Epoxy, or other high-strength two-part compounds. These products can withstand high pressure and temperature, making them ideal for sealing cracks or pinholes in drain lines. Professional plumbers often use industrial-grade epoxy liners for trenchless repairs that permanently restore the pipe from the inside.

The cost depends on the method and extent of damage:
Trenchless repair: $4,000–$15,000 for most homes.
Traditional trench repair: $50–$450 per foot, plus cleanup costs.
While trenchless options seem more expensive upfront, they save money by avoiding floor, yard, and driveway damage. Companies like New Flow Plumbing provide free estimates to help homeowners choose the best repair plan.

A properly done trenchless repair or relining can last up to 50 years or more. The new epoxy or HDPE lining inside the old pipe acts like a brand-new pipe, resistant to corrosion and leaks. Temporary fixes like epoxy putty or clamps may only last a few months, depending on pressure and wear.

You can handle minor leaks temporarily using epoxy putty or a repair clamp, but cast iron pipe repair is usually not a DIY job. These pipes are heavy, brittle, and often located under floors or concrete. Trenchless repair methods require special tools and experience. For safety and durability, it’s better to call experts like New Flow Plumbing, who specialize in non-invasive pipe repair.

Watch for these signs:
Frequent backups in toilets, sinks, or showers.
Sewer odors inside the house.
Slow drains or water pooling in fixtures.
Unusual yard growth or soft spots on the lawn.
Foundation cracks or shifting caused by leaks.
These symptoms mean your pipes may be cracked or corroded and need professional inspection.

The best no-dig methods are pipe lining and pipe bursting. Pipe lining inserts a resin-coated tube inside the old pipe, hardening into a new one. Pipe bursting pulls a new HDPE pipe through the damaged one, breaking the old pipe apart. Both methods require minimal surface damage and can be done much faster than traditional excavation. Professionals at New Flow Plumbing use these techniques to fix underground pipes quickly and cleanly.

Arman Personal Passport Size Image

Arman Grigoryan

Founder & President of New Flow Plumbing

Arman Grigoryan is the founder and president of New Flow Plumbing, proudly serving Los Angeles, Sacramento, and surrounding areas. With extensive experience in plumbing diagnostics, he leads a skilled team specializing in advanced sewer and drain camera inspections to quickly identify problems and deliver lasting solutions. Arman is dedicated to using the latest technology to provide reliable service, honest answers, and dependable results for every customer.

Get In Touch

Interested in discussing your plumbing fixture needs with our specialists? Call: 310-299-9284