In the last post, we looked at copper, and how copper plumbing works (and deteriorates) in household plumbing systems. Today, we’ll look at three other common materials – galvanized steel, brass and PVC – to see how they may fit into a replacement plumbing plan for your house.
Replacement plumbing options
Galvanized steel isn’t usually used anymore for new residential construction, but it is still used frequently in commercial construction and in fire suppression systems. Galvanized pipe has a rated lifespan of between 30 and 50 years, but like copper, the actual performance of the pipe depends upon the water it’s carrying, the pressure in the system and the environment it’s installed in. As galvanized pipe ages, it loses the zinc coating on the inside of the pipe. Once the coating has been lost, the pipe begins to rust, and you may see rusty water being discharged from the tap initially after you open it.
Galvanized pipe also develops a mineralization layer that decreases the inner diameter of the pipe. Eventually a pipe can become permanently clogged with minerals and must be replaced. Rust is unsightly to be sure, but free iron in the water is less harmful to your health than free copper. At the same time, iron in large quantities can also be toxic, so the best plan is to replace aging galvanized pipe when it shows early signs of failure.
Brass is an alloy of copper and zinc. Copper is relatively soft; brass is much harder. It’s also better at resisting corrosion. Chorine, which is often used in municipal water treatment, can cause the zinc to leach out of brass if the zinc content in the brass is too high. At one time, brass was used for piping, but it’s crazy expensive! Brass is still used for saltwater piping system and fittings. You can still find brass pipe, if you truly need (or want) to replace brass with brass. Under the right circumstances, brass pipes can last between 75-100 years, which is good because it will take you about that long to save up for brass replacements. Seriously though, other less expensive replacement plumbing materials can perform just as well as brass and are remarkably less expensive.
PVC is a relative newcomer to the plumbing world. It can be used in new construction, or in replacement plumbing applications. Its anticipated lifespan is somewhere between 50 and 100 or more years. Or one hard winter, depending upon who you talk to! The truth is that PVC lifespan estimates are guesses because we don’t have a really good idea of how long PVC pipes can last, or how they might deteriorate over long periods of time.
Some people worry that PVC pipes release harmful chemicals into fresh water, and tests have shown that water can pick up chemicals from some plastic pipes but to date, no plastic piping has exceeded the standards established by NSF/ANSI Standard 61, which regulates drinking water system components. Scientists have found wide variations in the amount of chemicals leaching from different brands of plastic piping, and consumers sometimes notice that water carried by plastic pipes may have a strange odor. This leads them to conclude that leaching is a by-product of the plastic production process, and regulating the production process more closely could reduce or eliminate most leaching issues in plastic pipe.
PVC buried in the soil can crack if it freezes. It is also vulnerable to damage from UV radiation, so it should not be used (for water) in areas where it will have direct exposure to sunlight. If PVC pipe will be exposed to direct sunlight following installation, it should be painted, insulated or otherwise wrapped. As with other piping materials, overpressure can damage PVC pipes. PVC that is buried directly in the ground can be damaged by physical contact with rocks, roots and other hard objects. It can also be damaged by the movement of the soil. PVC that is buried in the soil is usually placed on a bed of sand to minimize mechanical damage. Poor installation can also cause PVC pipe to fail prematurely.
In the next post, we’ll look at lead, polybutylene and bituminous fiber pipe, three kinds of pipe that could be in your plumbing system today, but shouldn’t be! If you’d like to consult with us at Boston Standard Plumbing & Heating, please give us a call anytime at (617) 288-2911. We can identify weakened plumbing components and help you develop a repair/replacement strategy that suits your situation.
Photo Credit: Jim Miner , via Flickr.com