Is Cast Iron Plumbing Worth It?

Cast iron plumbing is known for its durability, but it’s also quite expensive. This makes some people think twice about whether it’s worthwhile, especially when building a new house. So, is cast iron plumbing worth it?

Cast iron plumbing is worth it if your property has sandy soil, as it won’t quickly degrade in the ground. However, highly acidic clay soil can quickly degrade cast iron pipes, increasing the risk for cracks and bursting. Cast iron plumbing is expensive upfront, but it can last for 50 to 100 years in many cases.

That said, cast iron plumbing is prone to corrosion and sagging in soft soil. It’s worth consulting a plumber or construction contractor before deciding on plumbing materials. Follow along as we explore whether cast iron plumbing is worth it.

Pros And Cons Of Cast Iron Plumbing

It’s hard to say “cast iron plumbing is bad” or “cast iron is the best plumbing metal”. That’s because like many other materials, cast iron has many benefits and downsides. Follow along as we highlight the pros and cons of cast iron plumbing, so you can decide if it’s worth it.

Pros

It Lasts A Long Time

Cast iron is among the longest-lasting plumbing materials, alongside copper and brass. This is the main reason so many homeowners and plumbers believe that cast iron plumbing is a worthy investment. Thick and durable, this pipe material can withstand high pressure much better than other plumbing materials, like PVC.

You can expect cast iron plumbing to last 75 to 100 years under ideal conditions. Brass, on the other hand, can last up to 100 years, but can deterioate in as little as 40 years. Galvanized steel is another good option, but cast iron plumbing can outlast it by up to 50 years. This is largely because cast iron plumbing isn’t as prone to internal corrosion as some other metals, although it will eventually corrode due to consistent moisture. Cast iron pipes last the longest in sandy soil as opposed to clay soil. 

Non-Combustible

Cast iron plumbing is non-combustible, which can make your home safer from fire hazards. It’s much safer than plastic pipes, which have low melting points. For that reason, plastic pipes can make a fire worse and many people want to avoid that risk. Luckily, cast iron doesn’t release any toxic or flammable gases as it burns. Cast iron, copper, and stainless steel have some of the highest melting points in metal plumbing.

Superior Durability

Much of a home’s plumbing sits beneath the ground, out of sight. Because of that, it's not only vulnerable to water pressure, but also soil pressure and acidity. However, cast iron plumbing can withstand shifting soil better than many other metals. That’s because cast iron is rigid and heavy, so it’s unlikely to collapse under heavy soil. You don’t have to worry about rodents chewing through cast iron pipes, as you would with lead or PVC pipes. While soil acidity can affect cast iron pipes, it typically takes years for damage to become noticeable. 

Cast Iron Is Quiet

Anyone who has lived in a house with copper or PVC pipes is likely used to hearing pipes move and settle. This happens due to thermal expansion when the temperature fluctuates. Thermal expansion and high water pressure can cause banging, thumping, and whistling sounds. That’s not an issue with cast iron plumbing, which is very dense. Cast iron pipes can eventually become louder with time as they degrade. Until then, your pipes should stay quiet.

Cons

High Initial/Replacement Cost

The high cost of cast iron plumbing is the biggest downside. For example, a full cast iron plumbing installation can easily cost $15,000 or more. Smaller installations may cost as little as $3,000, but that’s mostly when replacing small sections. Installing cast iron beneath concrete slabs can cost $175 per linear foot, which is out of many people’s price range. Not only does this add thousands of dollars to construction costs, but it also means replacements will be expensive. The process is quite labor-intensive, and the material itself is too expensive for many people.

Prone To Corrosion

Every single plumbing metal is prone to corrosion, and cast iron pipes are no different. This corrosion can form inside the pipes due to prolonged moisture, as water sits in them indefinitely. However, some people fail to consider the external corrosion caused by soil acidity.

Highly acidic soil can oxidize and weaken even the most durable cast iron pipes. Construction contractors test soil acidity before breaking ground, as it can affect the foundation, plumbing, and gas lines. Honest contractors will likely explain why some materials may not work well based on your property’s soil acidity. Soil with a pH below 5.0 can quickly degrade cast iron pipes. That said, you won’t likely notice heavy corrosion until the pipes are at least 50 years old. A humid, rainy climate and acidic soil, in some cases, can expedite that timeline.

There May Be Lead Joints

Do you live in an old house with cast iron plumbing? If so, there’s a chance that the plumbing has lead joints, as they were widely used for many years. Congress banned lead pipes in 1986, but it didn’t require homeowners to remove existing lead. Because of that, some old homes still contain lead pipes and plumbing joints. Lead joints were commonly used in conjunction with cast iron pipes. This isn’t as bad as using lead pipes, but lead joints are still dangerous.

That’s because these joints and small riser pipes can connect the cast iron pipes to the main line. This means lead contamination is possible, despite your pipes being made of cast iron. However, you don’t have to worry about this if you don’t have lead joints.  

It’s Heavy Enough To Crack

Cast iron is much heavier than PVC, aluminum, and titanium, which isn’t always a good thing. That’s because cast iron pipes are heavy enough to sink into the soil, which increases the likelihood they will crack. Once cast iron pipes crack, water can leak out and damage the nearby foundation. If the pipe releases wastewater, a serious sanitary issue will arise. Cast iron pipes are more likely to sink in soft soil. Above-ground cast iron pipes can also sag and potentially burst in your home. This can result in thousands of dollars in water damage.

Summing It Up

Cast iron plumbing is worth it if you can afford the high upfront cost. However, you may want to think twice before installing cast iron in soft, acidic soil. That’s because cast iron is prone to corrosion and high acidity, and external moisture can accelerate the deterioration. 

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• How Does Plumbing Work In An Apartment Building?
• Why Do I Hear Water Dripping/Flowing Under My Stairs?