Cast Iron Pipe Life Expectancy: How Long Is It?

Most homes and buildings were built with cast iron sewer pipes until about the mid-1980s. And given that cast iron pipes have a life expectancy threshold, deciding whether or not to replace your cast iron system is a good question to start asking yourself.

So what is the life expectancy for a cast iron sewer system? In our experience, at most, cast iron sewer pipes can last about 50 years. However, we’ve seen a 50-year-old system that was fine and a 20-year-old system that was falling apart.

What Is Cast Iron?

Cast iron is a metal alloy made of iron, carbon, and silicone. Because it’s not malleable, it is cast (hence the name) in a mold to create things like pipes and cookware.

It was a popular material for pipes thanks to its durability and availability. And it was used for plumbing pipes for the bulk of the 19th and 20th centuries until PVC came on the market.

Since it’s cheaper and easier to install, more builders and homeowners started opting for PVC for their sewer systems.

Cast Iron Sewer Pipes in D/FW

In the Dallas/Fort Worth area, builders continued to use cast iron pipes until around 1980. But you can still find homes built up to 1985 that were built with cast iron systems.

And as with the rest of the country, PVC became the pipe of choice for underslab sewer systems in D/FW.

Cast Iron Pipe Problems

Cast iron is incredibly strong and can be long-lasting. Consider cast iron pots and pans that have been handed down from generation to generation.

But cast iron sewer pipes are a different case altogether. It’s impossible to care for pipes that are buried underground and have waste and water running through them.

Can cast iron pipes corrode?

The short answer: Yes, all metals can corrode.

If nothing ever touched the pipes, the cast iron could last for 75 or more years. But think about your sewer pipes. They are most likely being used every single day.

First, the pipes are buried underground leaving them vulnerable to the soil conditions. The clay soil in North Texas expands as it gets wet and contracts as it dries which affects the pipes and the stability of the entire system.

Next, think about what’s running through the pipes. On a good day you’ve got water, food particles, grease, soap, detergent, toilet paper, human waste, etc.

All of these things contribute to cast iron sewer pipe corrosion — not can contribute; does contribute.

And everyone’s experienced a slow drain from time to time so if any chemical drain cleaners are used, those contribute greatly to the corroding of your pipes. Using these cleaners is potentially more damaging than other methods of clearing up a drain clog.

In fact, the big players in reducing the longevity of a cast iron system are grease and drain cleaner chemicals.

Cast iron sewer pipe scaling

Along with corrosion, there is the issue of buildup in your pipes.

The combination of water and pipes almost always results in rust and rust buildup (which also contributes to the corrosion, by the way). And after decades of use, it’s natural for the materials that run through the pipes to stick to and build up along the inside walls of the pipes.

And with this buildup comes slow drains, clogs, and stoppages.

There are methods for removing this buildup/scale. But if you consider the nature of the material, years of water, waste, and materials running through the pipes have already weakened the metal. So much so that a common method for descaling cast iron pipes, hydro jetting, can’t be used because the pipes won’t be able to withstand the pressure.

There are also machines that can be used to remove this buildup, but again, if the pipes are already weak and corroding which is highly likely, it’s wasted effort and money spent.

Not to mention, if you have any leaks in your system, taking the time and spending the money on descaling your pipes is pointless since you probably need to replace the system anyway.

Why We Don’t Repair Cast Iron Sewer Leaks

I talk at length on the blog about why we not only recommend but will only replace a cast iron sewer system. But let me quickly go over it here.

As I mentioned earlier in the post, cast iron systems can last up to 50 years — and 50 years is a very optimistic number.

Almost all of the systems we’ve come across in the last few years need to be replaced. Until recently, we did try to repair the leaks. But we found that not only was it pointless but it was getting harder for us to do.

Let me explain.

To repair a cast iron pipe leak, we cut out the portion with the leak and replace that section with PVC. This means that because the pipe is bad there will very soon be two more leaks, one on each side of the PVC where it’s connected to the cast iron.

Also because the cast iron is bad, we find once we’re under the slab, we have to do what we call “chasing pipe.” This means we have to find a keep going down the line to find a piece of pipe to attach the PVC replacement part. And since most cast iron is in bad shape, finding a viable piece is becoming almost impossible.

Coming across these situations time and time again is why we no longer do repairs on cast iron sewer systems.

A Plan for Your Sewer Pipes

We understand replacing the cast iron sewer pipes under your home is an intimidating venture, particularly when it comes to cost.

But don’t let the cost of replacing your cast iron system scare you into making a short-term fix.
Instead, give us a call and we can discuss your options. We work hard to keep costs down as much as possible, “A” work for a “C” price, as well as evaluating your specific home and system to find the best plan for you. We also have financing available.

We’re available by phone at 972-494-1750. And you can send us an email at service@inhouseplumbingcompany.com anytime.