Polybutylene Piping Systems - An overview
Polybutylene piping systems (PB plumbing) was installed in an estimated six million homes between January 1,1978 and July 31,1995.

In some areas of the country, stockpiles of materials allowed builders and plumbers to continue beyond July, 1995, although it is not known how far

PB pipe, is often referred to as plastic pipe, but is one of many types of plastic piping. It is somewhat flexible and usually gray, as opposed to PVC or
CPVC products that are rigid and usually white or off-white. The pipes are joined by plastic or metal fittings held in place by aluminum or copper bands
(called crimp-rings), about the diameter of a quarter. PB pipe might be located in an attic, crawl space, or water heater closet, but is often installed
beneath insulation materials. It is not used for drains, waste or vent piping, yard sprinkler systems, irrigation systems, fire sprinkler systems, sewer lines,
faucets or fixtures.

There is no official estimation of how long the components will last in homes.

PB systems included many design changes over the years while the products were available for residential use.
Due to issues that were discovered along the way, the fitting materials and fitting designs changed, the crimp rings were changed to a brass or copper
instead of aluminum, a coating was apparently added to the interior of the tubing or pipe, and changes were made to the tools used for installation - along
with new guidelines for where and how the system should be installed.

We now know that the system and components may be prone to leaking, but information is relatively scarce relating to specific reasons for failures, and
scientific evidence to back up the speculation is even more difficult to find.

PB has been the source of much discussion by Home Inspectors, Realtors, Plumbers, Insurance Companies, Banks, and others.  There has been a large
class-action lawsuit related to failed systems, and a recovery fund was put in place to assist customers with claims (see link below for CPRC).

Surprisingly, some career plumbers, when asked about problems they have witnessed with PB in homes, speak of very few occurrences of leaks with
regard to the basic polybutylene components, with the exception of the early versions of plastic fittings, called Acetal pipe fittings (see image below).
Many also stated that performance of any type of plumbing is primarily a factor of how well it was installed, and that the quality varies quite a bit.

There seems to be a growing number of people that suspect that certain regions of the country may have had a disproportionately high percentage of
failed components of the PB system due to specific water treatment chemicals (chlorine, etc.). Also, there have been many more claims of failures made
for systems that were installed in mobile homes compared to standard site built homes... The leaks, some speculate, are also more likely to occur in
installation locations of large temperature swings, or just overly hot areas, such as mobile home walls and ceiling voids.

As stated earlier, there are very few official studies available, and scientific data is difficult to find when researching this plumbing type, there is plenty of
speculation, however, among those involved.

A word about researching PB on the web... There is a vast amount of information made available on the Internet regarding this particular plastic piping and
its related fittings. Be careful to consider the motives for some website owners though... If you are on a plumber's website, there is a good chance you will
see countless examples of why you should get rid of polybutylene piping... After all, they are selling re-piping / re-plumbing services to the public.

Please note that
all piping types have been documented to fail given certain circumstances, or if the piping is simply old enough;
Whether the piping is copper, galvanized, or plastic, it can leak.

The truly tough part about forming an opinion regarding PB, is that there are probably many hundreds of thousands of homes with PB piping that have
never had an issue, and some parts of the country appear to have not experienced the high failure rates that are so apparent in other areas...

The information below summarizes the variables that are suspected as playing a role in polybutylene leak events.

Possible causes - Installation related:

Defects in the material or connections that may have been caused during the installation, such as: Over-crimping & under-crimping of the rings that hold    
the piping material to the fittings.

Type (of metal) used for the "crimp-rings." Note: Aluminum was replaced with copper or brass early-on in the industry.  ( Well documented issues )

Bending of piping material that may have caused stress fractures, construction site damage to material, and poorly trained installers.

Storing or installing the piping system components in a place that exposes them to sunlight / U.V.deterioration.

Using the system with incorrect pressure limits set at the water source.

Use of Acetal type fittings that are subject to abnormally high deterioration rates. ( Well documented issue )

Temperature of water in piping too hot, or area of piping installation temperature being too high.

Possible causes - Age related:

Exposure to chlorine and other chemicals may oxidize or otherwise break down the material internally.

Long-term flexing or vibration to the material.

Age related changes in the plastic itself, which may make it more brittle.

Long term exposure to close proximity heat sources such as furnace flues, etc.
Resources and Links
Press Release posted at CPRC
Eligible Systems information from CPRC
Excluded Systems from CPRC
Claims made by people in various states of US
Interesting note:

There may be a significant factor associated
with water treatment chemicals & PB, and
also with the type of structure the piping
system was installed in (mobile home or
site-built home);

Some suspect that certain regions of the
country have treated water that is damaging
the piping and components, and that higher
temperature ranges related to mobile home
structures could be a major factor.

Idaho has apparently had only 95 home
repipe claims (paid by CPRC for qualified
events) over 13 years, as of this writing.

Could our water be a bit easier on this type
of system??
Left side: Copper fitting and crimp rings.

Right side: Acetal fitting and copper crimp rings.
Link to class action lawsuit information
Acetal fitting with interior deterioration