Plumbing pipe materials

Here’s a description of some of the primary materials that we’ve made water supply pipes and plumbing drain pipes from and their pros and cons.

There are three main types of pipes.

• There’s the water service pipe that connects underground from the water main out in the street into the house.
• There are the water supply pipes that connect to the water service pipe and carry fresh water throughout the house for drinking and bathing.
• There are drain, waste, and vent (DWV) pipes that carry the dirty waste water away from the sinks and tubs to the sewer or septic system.

Copper

Pros — Copper has a very long history of successful usage as a water supply pipe.  It’s very safe.  It lasts a very long time and is very durable.  And copper is required as the material for water supply pipes in Chicago and many of the suburbs around the Chicago area.

Cons – Copper has become very expensive.  If a copper water pipe freezes it’s likely to burst, which will cause a possibly huge water leak once the ice melts.  There are some reports that excessively hard or soft water can cause problems with copper pipes and allow pinhole leaks to develop, especially if the water has a low pH level.  That’s generally not much of a problem in the Chicago area where water comes from Lake Michigan.  But in other parts of the country and even in the outlying Chicago areas that use well water this can potentially be a problem.  Also, because it’s so expensive there are reports of low-quality copper being used in order to save money.  That just worsens the potential problem of pinhole leaks.

In the 1960’s and 1970’s copper was used as DWV (drain, waste, and vent) pipes.  It works very well for this application and it’s very durable, but because it’s much more expensive than other options it’s very rarely used as a DWV pipe today.  However, the City of Chicago requires copper DWV pipe in some buildings four stories and higher.

Galvanized steel

Pros – Galvanized steel was the material of choice for water supply pipes from at least the turn of the last century until sometime in the 1960’s.  It’s quite sturdy and can even hold up when subjected to freezing.

Cons – Galvanized steel isn’t really an option today, at least not for residential use.  It lasts a long time, but eventually the zinc coating (that is the galvanized part of the pipe) will erode away and you’re left with plain steel, and that of course will rust.  So leaks are a real possibility if the pipe corrodes all the way through.  Also, the rust builds up inside the pipe and that chokes off the flow of water, so your water flow is reduced – sometimes reduced very dramatically.  A homeowner whose house has galvanized steel water pipes needs to be ready to pay for replacement.  Galvanized steel is rather expensive, and it takes a long time to make connections.

When galvanized steel is used underground the rust and corrosion are much worse.  So when galvanized steel is used as the underground water service pipe (from the water main in the street into the house) you can expect corrosion and rust to be a big problem.  This often means bad water flow.  The only solution is to replace this pipe.

PEX – Cross-linked polyethylene

Pros – PEX has become the standard water supply pipe throughout much of the United States.  It’s been used in Europe for several decades, so it has a fairly long history.  It’s inexpensive to buy and generally inexpensive to install because it comes in very long reels that can be snaked through the house, and that means fewer fittings to install.  And the fittings that are needed go on faster than with copper.  It can stand up to freezing temperatures pretty well because it can expand in size quite a bit before it fails.  It’s chemically inert and won’t impart any chemicals to the water and it will stand up to most types of water – hard water, soft water, acidic water.  However, too much chlorine can cause problems with PEX pipes.  PEX has no scrap value so if theft of copper water pipes is of any concern this is a good alternative.

Cons – PEX is just plastic and so it’s definitely not as durable as copper or galvanized steel.  Rodents can chew it, and it can potentially rub against other pipes or the house structure as water flows or as it expands and contracts with changes in temperature.

CPVC – Chlorinated polyvinyl chloride

Pros – CPVC was introduced as a potable water supply pipe in 1959 so it has a fairly long history as a water supply pipe.  CPVC is much less expensive than copper.  It can withstand higher temperatures than PEX.  That’s really only a benefit if something goes wrong, but hey – sometimes things go wrong.  CPVC plastic has better corrosion resistance than copper and galvanized steel pipes, and it can stand up to chlorine better than PEX.  CPVC has no scrap value so if theft of copper water pipes is of any concern this is a good alternative.

Cons – CPVC is generally more expensive than PEX, and it takes longer to install because it can’t be bent and so any change of direction means several fittings need to be installed.

Lead

Pros – Lead pipes will last a very long time.

Cons – The adverse health effects of lead contamination are well known and extremely serious.  There are many lead water service pipes (the pipe from the water main out in the street into the house) still in service.  It’s generally understood that public water systems have added orthophosphate to the water supply, which creates a phosphate coating inside the pipe that inhibits the release of lead into the water.  However, the long-term ability of this type of coating to protect the pipe from leaching lead into the water involves many factors, not all of which are under the homeowner’s control.  If you have a lead water service pipe you should consider replacing it with some other type of material.

Cast iron

Pros – Cast iron is used as DWV (drain, waste, and vent) pipe in plumbing systems.  It has a long history of successful usage and it’s very durable.  It’s much more quiet than other types of DWV pipes used today so you’re less likely to hear pipe noises inside the wall.

Cons – Cast iron is very expensive, both the materials and the installation costs.  You’ll never see it installed today in a single family home, but it is used in some commercial and high-rise buildings because of its durability.  Very old cast iron can crack along its length.  This can allow leaks inside the walls and sewer odors to escape.

PVC

Pros – Polyvinyl Chloride (PVC) pipe is commonly used today as DWV (drain, waste, and vent) pipe in plumbing systems.  It’s inexpensive and fairly easy to install.  It has a long history of successful usage.

Cons – PVC drain pipes can be loud – you can easily hear the sound of water draining inside the walls.  Note that PVC is not acceptable as a potable water supply pipe, only as a drain pipe.

Polybutylene

Polybutylene is a type of plastic piping that was used for water supply lines in homes from the late 1970s to the mid-1990s.  It turns out that this material had tremendous durability problems.  Leaks were very common, leading to a class action lawsuit and millions of dollars of compensation.  Polybutylene pipes aren’t available anymore, and if you have them in your home you should replace them as soon as possible.