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  • Writer's pictureBonnie

Cast Iron Plumbing Pipes

Building science and construction standards have changed throughout time. Sometimes we realized that the material wasn't as awesome as we thought, whether durability- or safety-wise, and sometimes we developed better materials that became adopted as the new normal. Enter cast iron plumbing pipes.

Cast iron was commonly used in residential plumbing until the 1970s. By the 1980s, PVC (polyvinyl chloride) plastic plumbing became all the rage because it was so much lighter to carry and could be cut much easier than cast iron.

What Does Cast Iron Look Like?

Think of the iconic green pipes that Mario uses to enter a new scene, and you've got the visual. The connections bulge out to form a larger diameter, square-shaped hub. The color of the pipe is black (unless it is rusted like the left photo below).

What's the Problem?

A chemical reaction happens between the pipe material and the water/waste which causes corrosion. The most interesting fact about cast iron pipes is that they rust from the inside out. In the beginning stages, what you may notice in your home is slow drainage despite any anti-clogging attempts you've made. This is because the rust forming inside the pipe is constricting the flow of your drainage.

If I note any cast iron pipes during home inspections, I mark it down as the following recommendation:

"Cast iron pipes have not been installed in homes for decades. Any remaining cast iron pipes are at the end of their service life and likely require replacement. Recommend a licensed plumber assess these pipes for serviceability. "

Cast iron has a service life of roughly 50-100 years. Yes, that's quite a range. All that being said, if you have cast iron for drain pipes, you will likely need to replace and upgrade these pipes in the very near future. Plumbers can test the serviceability of the cast iron by performing a sewer scope. This test drops a camera down your plumbing pipes and documents any clogs, cracks, or gaps along the way,

This cast iron drain pipe has a small crack on its underbelly. Notice the water staining of the plastic sheet below? It's leaking rusty water which indicates there is rusting on the inside of the pipe. At this point, I'm sure the homeowner already noticed poor drainage.

Need a home inspection in Central Arkansas? Contact Honeybee Home Inspection LLC by calling or texting 502-501-3553 to schedule your home inspection or visit

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