Once the top choice for all water supply pipes, copper has been nudged a bit to the side by flexible pipes made from cross-linked polyethylene, “PEX” for short. While copper still plays an important role in water pipes for new construction, PEX pipe is quickly becoming the choice for remodeling and retrofitting. Both copper and PEX come with a few advantages and disadvantages, so if you’re looking to replace your home’s current water supply system, keep reading. This cheat sheet on PEX vs. copper outlines the main differences between the two materials so that you can make an educated decision for your plumbing project.

Copper lasts longer than PVC pipes.

It’s tough to beat copper pipes for longevity, which on average last 50 to 70 years, compared to PEX, which has an expected lifespan of 30 to 50 years. PEX’s life expectancy can be shortened by the use of extremely hot household water (180 degrees Fahrenheit or higher) or if the water in the home contains high levels of chlorine.

Copper’s life can be shortened by highly acidic water. When installed under typical conditions (i.e., your home is connected to a municipal water system), copper can be expected to outlast PEX by about 20 years. If you’re on a private well, have your water tested prior to retrofitting your water supply system. Local County Extension Offices can test well water to determine whether it’s high in acid or chlorine.

Copper is also costlier.

In recent years, the cost of copper has risen substantially due to its increased recycle value, so products made from copper have increased as well. On average, installing copper water pipes will be 58 percent to 68 percent more expensive than PEX. For example, you could expect to pay $8,000 to $10,000 to have a plumber replace the old pipes with new copper pipes in an average, two-bath, 1,500-square-foot home versus $4,000 to $6,000 for PEX.

PEX requires fewer connections.

Since copper is rigid, it must be cut to size and have elbow fittings installed every time it comes to a corner, such as where it turns from a vertical run between studs to a horizontal run to meet a sink. More connections mean more installation labor. PEX, on the other hand, runs continuously all the way from a water-distribution panel (called a manifold) to each fixture (tub, sink, etc.). PEX bends easily around corners so no additional connections are necessary.

In a remodeling project, flexibility is a big plus, because the PEX pipe can be snaked through finished walls without the need to cut out drywall. To have new copper pipes installed in a finished home, the drywall must be removed to give the plumber access to make connections.