Cast iron and copper water pipes dominated plumbing in the 20th century. It's only in recent years that plastic pipes have gained wide acceptance as an alternative, and iron and copper pies still make up a significant share of the market, since they're among the most reliable.
For many plumbers and property owners, choosing between iron and copper is tough. Both materials have advantages and disadvantages, and key factors to consider include durability, water purity, cost, and ease of installation.
Both cast iron and copper pipes are very durable, though iron is technically stronger than copper thanks to its molecular structure. However, iron pipes may also be more prone to developing leaks due to corrosion, especially around connection points. Copper pipes are more promising for smaller-scale applications, since they tend to corrode more slowly.
This difference is especially pronounced in more humid areas, where iron can tend to corrode even more quickly.
Copper pipes are often used in residential plumbing thanks to their low levels of leaching and corrosion. Although iron pipes don't contain high-risk toxins like lead pipes, their vulnerability to rust may still cause some concerns for drinking and bathing water. That's not to say copper pipes will never corrode, however, especially if they're transporting hard water.
Still, for home use, copper is the clear favorite. Some estimates say copper pipes are used in over 95% of residential plumbing systems.
For a long time, copper and cast iron pipes were used interchangeably, and essentially shared a price point. In recent years, though, more people have been shifting to iron due to the high cost of copper pipes. Copper stores are diminishing globally, so copper prices are rising accordingly. If cost is your main concern, you may want to consider cast iron.
Ease Of Installation
The installation process for copper piping is pretty much the same as for cast iron. However, copper pipes are a bit easier to handle. Copper is softer than iron, so copper pipes are easier to install using everyday home tools like pipe-cutters and jigsaws.
Copper pipes are also available in two types: soft and hard. Soft copper is mostly used for repair purposes, while hard copper is often used for new installations. You might find it less difficult to deal with soft copper for regular home repair projects, especially if you have to do any cutting. Both kinds of pipes come in diverse measurements, though, so if you plan your project carefully you can minimize the need for trimming.
In short, copper is the dominant choice for residential installations, and soft copper is the easiest material to use for repairs. Iron is cheaper and more durable, but more subject to corrosion, and a little more difficult to install and repair.
Both copper and cast iron pipes are good choices for water plumbing. However, for small-scale domestic water purposes, copper wins out. It's slightly costlier than iron as an upfront expense, but in the long run it's easier to maintain and repair.
This doesn't mean there's no place for cast iron pipes, though. Many large scale projects like irrigation systems or industrial plumbing will benefit significantly from the lower cost of iron. Even smaller projects can benefit from the cost difference, provided they don't involve drinking, cooking, or bathing water.