Cast Iron Pipes and what troubles they may cause. 

Cast iron pip leaks and causes pollution

Ruptured cast iron sewer pipeline which caused sewage leakage stream and pollution.

Cast iron pipe background

Cast iron pipes are a type of pipe that has been in use for plumbing since the 17th century. They were once considered innovative and modern. The wealthiest of the wealthy, including King Louis XIV of France, used these pipes.
In the United States, cast iron pipes date back to the early 19th century.  During the early years of cast iron installation, only the wealthy were able to afford it. The work involved in making and installing cast iron pipes is highly labor-intensive. In the early 1930s homes with indoor plumbing became more common and the only available option was cast iron. It is estimated that about 76 million homes in America had cast iron pipes installed over the decades they were used in piping. Here in Florida we commonly find cast iron pipes in homes that were built before 1975 but on occasion, it is found in homes built as late as the early 1980s. The material didn’t face any competition until the 1970s when plastic became more common to use in piping. They are no longer used because of the cost of production and they also don’t have the required flexibility to be durable in modern construction. The modern design of homes requires more flexible pipes of smaller sizes.
Cast iron pipes were considered the strongest material to use in early sewage systems, carrying water for hundreds of miles at a time. King Louis XIV of France used a 15-mile long pipe to connect the palace and surrounding town to a pumping station near the Seine river. It became more common for sewage piping in the United States some years after the 1930s because they outdid other pipe materials of the time due to their reliability. The pipes claim to have a 50-year life on average but in slab-built homes, the life can be limited to 25 years. Although cast iron pipes deteriorate over time, Cast iron pipes can last for over 100 hundred years in some rare cases. It all depends on the geographic location of the home and the pipes. They are hard to damage due to their strong material, which was designed to hold up under pressure when the water lines were full to capacity.

What went wrong with these strong, reliable cast-iron pipes?

Old home cast iron pipe section removal

Cast iron pipes went out of fashion in the 1980s. They were replaced by Polyvinyl Chloride plastic (PVC), which can be made quicker and more easily.  Cast iron pipes can corrode from the inside over time compromising their structural integrity. Consistent water flow and chemicals cause wear, rust, and damage.  A chemical reaction occurs to cast iron when water moves through the pipes, generating hydrogen sulfide gas. When hydrogen sulfide gas oxidizes it creates sulfuric acid that is corrosive to the pipe walls.  Because of the salt and moisture-rich environment, Florida homes are especially susceptible to this type of pipe corrosion. When the interior of the pipes corrode and rust, the walls of the pipe catch debris and create clogs. People with long hair who have cast iron pipes may notice their pipes become clogged frequently. This is a common issue due to the hair catching on the corroded walls and clumping creating a net for soap residue and other material.

  • Sewer Back-Up Into Home
  • Clogged Drains
  • Water Damage To Home

Corrosion, root growth and clogs of cast iron pipe section

Cast iron is not a bad pipe when first installed and problems do not start for some time. Unfortunately, cast iron pipes are at or reaching the life expectancy and they must be replaced sooner rather than later. In Florida alone, nearly two and a half million of the 76 million homes across the United States, are at risk of severe plumbing problems and need attention. A home with cast iron is not or should not be a deal-breaker, in some cases, you may move in and have only minor issues for some years. The catch is that you should be mindful that they will need repair or replacement in the future. Another important note is to be cognizant of the products you pour down the drain. There are many different chemical drain cleaners. Some of them contain a high concentration of sulfuric acid, while others may contain peroxide, bleach, etc. Most chemical-based cleaners generate heat inside the pipe; Metal-based pipes such as galvanized steel and cast iron can corrode. If you want to try a home-based chemical remedy, try vinegar and baking soda. They pose no danger whatsoever to your pipes. This is done by introducing a quantity of baking soda down the drain, then adding vinegar. Then seal the drain outlet tightly. The baking soda and vinegar will react, creating pressure inside the drain. It is recommended to wait at least 15 minutes or so, before checking to see if the clog is cleared. A follow-up with boiling water is also a good idea. Pouring a kettle of boiling water into the sink may help clear a clog. If you decide to use boiling water, do not transfer it from the kettle to another receptacle. The water must be poured directly from the kettle, and as near to the boiling temperature as possible. Make sure to pour it directly down the drain, as boiling water may harm certain surfaces. This trick works best with metal pipes because they withstand high temperatures. A temperature of more than 175 degrees F can melt the joints in PVC.”

A few common issues to watch out for:

  • Cast Iron pipe with crack

    4 inch cast iron pipe with a large crack in a crawl space

Signs to help determine if compromise of pipes may have occurred. 

    • Slow drain
    • Toilets or drains that are constantly backing up
    • Leaks
    • Nasty orders
    • Rodent or roach infestation
    • Gurgling noises coming from pipes
  • Ground/soil movement
  • Moisture in the ground
  • Mold Growth
  • Cracks and breaks
    • Damages can cause leaking sewage underneath the dwelling and possibly cause structural damage.

sewer scope view of the interior of a cast iron pipe with corrosion

Cast iron pipes still in use with older homes are at risk of being affected by tree roots. Tree roots can grow into and damage pipes and can lead to backups. There have been many cases where tree roots end up damaging the cast iron material, which isn’t good for water transfer. The resulting leaks can cause contamination known as black water which is a form of dark, dirty water that can be full of backed-up sewage, rust, bacteria, and fungi. Broken or damaged pipes can also cause leaks and standing water in your floor and ceiling.
Plumbing pipes can leak or burst, resulting in expensive bills to repair the plumbing and your home. Water can damage your belongings, contribute to mold growth, encourage termite infestations, and affect the structure of your house.

Obtaining Insurance for cast-iron piped homes.

Florida homes are especially susceptible to pipe corrosion because of the salt and moisture-rich environment.  Many residents are finding that their insurance companies are not covering costs related to water damage due to corroded plumbing. Even if the effects of water damage can be quite significant and cost upwards of $10,000-$30,000 to repair or more. At a low estimated average of $10,000 per home, we are talking about $760 billion in damages and repairs that need to be made across the United States. This makes cast irons a massive problem for insurance companies. 

  • Cast Iron pipes are revealed during an inspection 
    • A 4- point is a required insurance inspection for homes on average older than 15 to 20 years depending on the carrier.
  • Companies may require higher insurance premiums
  • Companies may request the pipes be replaced
  • Make sure your homeowner’s insurance policy covers replacing compromised cast iron pipes. As well as the terms of replacement. For instance, some insurance carriers require you to notify them within a certain time frame after the failure occurs.

Repair/replacement of cast-iron


  • PVC has the required strength to be durable for long-term use, and is cheaper and easier to make, making them the preferred option over cast iron.
  • Broken portions of pipes outside are considered to be much easier to repair or replace costing slightly less
  • Cost on the low end is estimated to be a few thousand up to thousands depending on home location and location of the pipes.
    • Slab or crawlspace plays a large part in cost as well
  • If cast iron is underneath a concrete slab the concrete will need to be opened to expose the pipes.
    • Replacement of the pipes, new concrete for the slab, interior features such as flooring and cabinets will all need to be replaced/ reinstalled.
    • Some plumbers may suggest leaving the old pipe and running new pipes in a different setup to reduce the cost and added labor 
      • Some examples would be digging underneath the slab from the outside or relining the inside of the cast iron sometimes called “slip” lining,
        • Relining cast iron is not always possible; it depends on the condition of the pipes and the experience of the plumber.

These costs are estimated based on averages, your cost may differ. Speak with a local plumbing company for pricing.

  • Replacing a cast iron pipe without water damage will be much cheaper. If you have a cast-iron problem that causes water damage it is not going to be cheap.
  • Replacing all of the plumbing in a 1,500 square foot home could cost between $8,000 and $15,000.
  • However, this doesn’t include water damage done to your property which could add another $10,000 – $30,000.

Repairs Should be Left to Professionals

The market is full of DIY products and you don’t want to pay a contractor to do a job you can complete yourself. With plumbing repairs, you may think you have done a good job, but your inexperience may not fix the problem and could cause other issues. To prevent plumbing leaks, repairs and installation of new components should be left to a professional. You will be confident that everything has been properly assembled, joined, and repaired.

  • With this type of work, it is extremely important that you use a licensed plumber with experience. This is not a simple job and it requires very technical knowledge.


  •  sewer scope of drain pipes showing tree root clog


First, you should determine if your home has cast iron plumbing. If it does, it is a good idea to have a deeper inspection of the piping system. As home inspectors, we can assist with this by doing a video scope to determine the condition of the pipe interior.

Sewer scope inspection

  • Looks inside pipes and is capable of finding: 
    • Root growth
      • This type of damage causes leaks, backups, possible structural damage.
  • Large Cracks
  • Collapses
  • Narrowing

If the sewer scope shows 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 an inspection 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 them repaired or replaced sooner rather than later. An alternative to replacement is known as trenchless or “slip” lining 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!


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 could actually last for over 100 hundred years in rare cases. It all depends on the geographic location of the home, the pipe location, and the amount of time with consistent use. 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. Many of the municipal pipelines and commercial buildings across the US still have cast iron pipes working just fine. Another big plus is they’re quiet!
If you are a buyer, seller, or Real Estate agent the following link may be an interesting point of view. We have no affiliation with this company, a plumbers perspective in regards to plumbing is only a bonus.
A plumber’s POV on buying or selling a house with cast iron plumbing.

New Ground Home Inspections offers home inspections in Jacksonville, FL, and the surrounding areas. Contact us to request our services.