Cast iron plumbing has around for decades, and is still manufactured today. It is the old gold standard for drainpipes and is found in many older homes’ systems. Newer homes are typically built with PVC or ABS piping as it is cheaper, much lighter-weight, and less prone to corrosion. Plus, they’re easier to repair and are generally considered the gold standards today.

If your home has cast iron plumbing, this is neither a good or bad thing. But depending on a few factors (particularly the age) you need to be aware of a few things. Let’s talk about the advantages and disadvantages of cast iron plumbing! 

What is Cast Iron Plumbing?

Cast iron pipes were used for sewer drainage, or more specifically, DWV systems (Drain, Waste, and Vent) for ages throughout the world. They are typically found in older homes that were built during or before the 1970s (early 1980s in some places), and cast iron was used for centuries. Cast iron pipes were favored for the durability of the material, their ability to handle water through them, and resistance damage, but they are generally no longer installed in residential settings today. 

Where is Cast Iron Piping Found? 

The majority of homes built before 1975 were built with cast iron pipes in the plumbing system, although it was still installed into the early 1980s in some places. Yes, cast iron is a durable and strong material, but it has some drawbacks. The most common issue is that it deteriorates over time – often unseen from the pipe’s interior. This means you may not even know you have an issue until you have a sewer backup.

According to InterNACHI, the life expectancy of Cast Iron Waste Pipes in Florida is about 40-60 years, but every situation can vary. Some homeowners have even found that their cast iron begins to deteriorate after about 25-years, which means that many of the homes built with original cast iron piping systems may be beginning to have plumbing/drainage issues today, or could soon have an issue.

Disadvantages of Cast Iron Pipes

Cast iron pipes were favored for many years for their strength. However, homeowners and builders have begun to realize that they aren’t as durable for a long period of time and better materials are available today. 

Over time, there are specific issues that almost always pop up in homes built with cast iron plumbing systems.

Common Issues with Cast Iron Damage Include: 

• Corrosion – this is almost always the first issue that will take place, often from the pipe’s interior that you can’t see.
• Cast iron is very heavy – which can lead to sinking in the ground and can cause cracking. It’s also harder to repair.
• Clogged & slow drains
• Sewer backup into homes, which can lead to:
  • Water damage
  • Unsanitary conditions
  • Pest infestations
  • Can allow mold to grow 
• Expensive, messy repairs – you may even have to have the slab removed in places to replace it. This is costly and messy, and you could even be displaced from the home for a while in some cases.
• Insurance may not cover repairs – be sure to check your homeowners’ policy for specific exclusions. In some cases they may be required to fix the issue, but not always. Litigation seems to be ongoing about this issue.

Dangers of Cast Iron Pipes

Cast iron isn’t inherently dangerous. However, the connections/joints do often contain lead, which has known health concerns when consumed. Since these pipes aren’t used for drinking (i.e. potable) water, that isn’t generally a concern, but repairs should only be performed by qualified professional contractors.

Since cast iron is made of metal, when the pipes have waste flowing through them, hydrogen sulfide gas is created as a chemical reaction between the waste and cast iron. When the gas oxidizes, sulfuric acid is created and causes corrosion within the pipes, which results in the common rusting pipes from the inside out.

The rust that is created is the main reason that the pipelines can become clogged, as the rust flakes can gather, swell and form a block in the line’s flow. As this deteriorates the pipe wall, it can also invite tree roots to penetrate, further impacting the problem. 

When sewage backs up into the home, this obviously invites unsanitary conditions that can be a health hazard. Not to mention damage to the property from moisture exposure. It must be fixed at this point, and the fix can sometimes be expensive and quite messy.

Should I buy a home with Cast Iron Pipes?

We ultimately can’t provide you with a definitive “yes or no” take on this, as we never try to steer buyers in the direction of buying a home or not. We simply aim to provide you facts about the home’s condition, but the individual choice must be your own. However, know that in some places it may be tough to avoid these pipes entirely – especially in localities with an older housing stock. Our opinion is that cast iron pipes should not be an immediate deal-breaker, but you must do your due diligence. You should always have a licensed plumber scope these pipes to determine their interior condition during your inspection period, while you still have time to act. If they are damaged or heavily corroded, you (or the seller) should have them fixed or replaced. Whenever we see cast iron piping present in a home during an inspection, we always recommend they be scoped by a qualified licensed plumber in our inspection reports, as we also cannot see their interior condition.

Advantages of Cast Iron Pipes

Although cast iron pipes deteriorate over time, the reality is that most older homes have at least some cast iron plumbing that is still intact. Cast iron pipes have lasted for over 100 hundred years in some cases, depending on the geographic location of the home and the pipes. 

While homes with cast iron pipes laid in clay soil tend to be more likely to have corrosion, homes built in sandy soil often have pipes that last longer. 

Cast iron is durable and strong, which is why it has been used for so long, and in fact, many of the municipal pipelines and commercial buildings across the US still have cast iron pipes that are working just fine. Another big plus, is they’re quiet! Here’s one of our favorite builders to watch on YouTube, who actually installed them recently (as of 2021) in some places in his own home, for this very reason! However, they generally just aren’t recommended to be installed anymore, especially with more reliable materials available.

What Do I Do if My Home has Cast Iron Plumbing?

First, you should determine if your home has cast iron plumbing. As a home inspector, we can assist with this. If it does, it is a good idea to have a qualified licensed plumber come out to your home for a deeper inspection of the piping system. Often they will video-scope them to determine the condition of the pipe interior.

If the plumber determines that your pipes are still in good condition and working properly, then you don’t need to worry about making a change right away. However, you should take note of this and make sure to have a plumber come out every year or so to re-assess the condition of your pipes. Also, check your homeowners’ insurance policy for any exclusions on drain piping, sewer backups, etc., and you may even consider budgeting today for future repairs that may be needed on a “rainy-day.”

If your pipes are starting to deteriorate, you’ll want to look into having the sections that are damaged replaced sooner rather than later. An alternative to replacement is known as trenchless pipe repair. This is where they reline the pipes with an epoxy-based material that makes them smooth and good as new. This is definitely better than having your slab cracked open, but the old pipes have to still have some degree of integrity to them, so don’t wait too long if you want this done.

Damaged pipes can result in messy, unsanitary, and costly repairs if they are not repaired, so you’ll save more money in the long run by being proactive!