How to Replace Cast Iron Sewer Pipe

Cast iron pipes have been in use for sewer pipes way back before the 1970s. These pipes were built to be stronger and last way over 50 years. They are commonly identified by their blackish-brown color and the hard material that they are made of.

Even with their hard material and durability, nature has always found a way to break them down over time. So, at some point in life, you will require to replace your old cast iron sewer pipe in your home.

As such, in this post, we look at how to replace cast iron sewer pipes. Besides, we look at the common signs of cast iron drain pipe failing and how much it might cost you to either repair or replace your damaged cast iron drain pipes.

Signs that your Cast Iron Sewer Pipe Needs to be Replaced

There are several signs that indicate your cast iron sewer line is in bad shape and required replacement. Here are some of the signs to look out for:

Discolored water or Foul Odor

If you are experiencing sewer gas odor around your home, then you might have a cracked sewer pipe. Equally, if yellowish or brownish water is flowing out of your tap, it is a sign of rust or corrosion which means that your cast iron pipes are rusting and possibly nearing their lifespan.


If you are experiencing slow draining, clogs, or sewer backups, then it is an indication that your pipes are failing.


If you are experiencing persistent leaks, they may be as a result of cracks in your pipes. If you think that the leaks are persistent with no apparent reason, check your pipes.

Mold Growth

If you have cracked pipes leaking behind the walls, there is a possibility that molds will grow. This is because molds only require at least 55% humidity for successful growth.

Foundation cracks

Leaking pipes can greatly disrupt your foundation and cause floors, walls, or ceilings to crack. Hire a foundation repair specialist or a professional plumber to inspect your plumbing system to find out the problem before the situation gets out of hand.

Strange lawn signs

Leaking sewage can act as a fertilizer and once it leaks into your lawn, grass can experience excessive growth or a lush green color. Besides, if you notice puddles of sewage water or sewage waste in your yard, it might be a sign of a cracked and leaking sewer line. Moreover, your soil can also sink or develop strange bumps or ditches because of soil dissipating.

Rodents or insect infestations

Rodents and insects such as palmetto bugs, flies, and cockroaches can find their way into your house even though the tiniest of the cracks in your pipes. So, if you are experiencing an extraordinary rodents or insects’ infestation then it is a sign of damage to your cast iron plumbing.

Should I Repair or Replace Cast Iron Pipes?

Since the cast iron pipes are made to last more than 50 years, it is best if you replace the cast iron plumbing system soon if you start experiencing deterioration. There are several factors that result in the breakdown of cast iron pipes and repairing your cast iron piping system is just but a temporary solution to a problem that may persist, especially if your iron pipes have reached their lifespan.

Repairing your cast iron pipe can be a great option to quickly bring the situation under control, but this is not the solution to your problem. Once you do repairs to your cast iron pipe, the pipe will at some point crack, crumble leak, or break on either side of the repair. This is just the nature of a cast iron pipe.

However, if you have to budget for a cast iron pipe replacement project or immediately stop a leak and manage further water damage in your home, you can have a spot repair done to the pipe. But aim at replacing your pipes soon.

How to Replace Cast Iron Sewer Pipe

There are some ways of replacing cast iron sewer pipe without necessarily tearing up your property.

Trenchless Drain Pipe Replacement

The trenchless cast iron sewer replacement requires one or two access points, usually 4×4 pits on either side of the house. You can make an access point by pulling off a toilet – it will be reinstalled. The concrete slab may be chipped away under the toilet. However, it is a better option compared to having an ugly trench through your kitchen or living room. The trenchless sewer repair often begins with hydro-jetting or any other pipe cleaning solution you may prefer.

The trenchless cast iron sewer pipe repair is divided into two subtypes:

Pipe Lining

Pipe lining is a sewer pipe repair in which a plumber’s epoxy-impregnated liner is inserted into the old damaged pipe, inflates to create a new pipe structure insider the old one. Pipe lining can be a replacement or repair based on whether the entire length of your plumbing system is lined or simply a section.

If it is a section of the pipe that is lined, then it is a repair, but if the entire piping system from the start to finish is lined then it is a replacement because you are getting a whole new pipe system installed.

Pipe Bursting

Pipe bursting involves attaching a new high-density polyethylene pipe to a winch with a cone-shaped bursting head and pulling it through the damaged line. As it is pulled through, the old damaged pipe will be broken apart as the new one takes its place. Compared to pipe lining, pipe bursting is way cheaper.

Conventional Drain Pipe Replacement

Conventional sewer pipe replacement involves digging up all the damaged pipes and replacing cast iron pipes with new ones. The process will probably include the chipping of concrete, ripping up of floors, tearing down walls, and trenching through your lawn and home.

Although this process is quite tedious and time-consuming, it is way cheaper than pipe bursting and pipe lining. Besides, it is the most ideal when your pipes are not candidates for trenchless sewer pipe repair or replacement.

What is the Cost of Replacing Cast Iron Sewer Pipes?

Certainly, the cost of replacing your cast iron drain pipes depends on various factors including the locality where you live. Regardless of these factors, budget to spend $175 per foot on average. However, bear in mind that other costs such as the cost of cutting and replacing the concrete slab, the cost of a hotel – you will require to stay somewhere as the replacement takes place, the cost of replacing damaged tiles among others will be included.

Structural Pipe Lining

Structural pipe lining is a pipe replacement process in which a pipe-within-a-pipe is created using a felt liner and a special epoxy. So, if you are looking to rehabilitate your damaged cast iron drain pipe through structural pipe lining or cured-in-place pipe lining then it will cost you between $135 to $185 per foot.

Pipe Bursting

If your damaged cast iron pipe doesn’t have the structural integrity necessary for pipe lining, then pipe bursting may be an ideal option. Pipe bursting is a trenchless method of replacing the old pipe by pulling a brand new one into it. If you opt for this replacement process, it may cost you between $145 to $195 per foot.

Brush Coating or Spray Lining

Consider brush coating or spray lining or brush coating as structural pipe lining without the structure. This pipe replacement involves spraying a flexible polymer resin directly onto the inner surface of your damaged cast iron pipe. Spray lining or brush coating can cost you between $200 to $285 per foot.


Knowing how to replace cast iron sewer pipe can help you prevent major repairs from having to be done to your plumbing system. You can also call in a plumber for professional repair or replace your cast iron piping system in your home for a permanent solution.

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