Polybutylene (PB) Plumbing Pipe

Polybutylene (PB) was a plastic manufactured between 1978 and mid-1995 for piping in home plumbing systems. It was inexpensive and offered plenty of advantages over other materials, such as flexibility, ease of installation, resistance to freezing. Pipes made from polybutylene were installed in up to 10 million homes in the United States during that period. Despite its strengths, production was ceased in mid-1996 after scores of allegations surfaced claiming that polybutylene pipes were rupturing and causing property damage. In the homes containing this material, homeowners must either pay to have the pipes replaced or risk a potentially expensive plumbing failure. 

How Does Polybutylene Fail?

The University of Illinois at Chicago published two studies that have shown that disinfectants can react negatively with polybutylene. That reaction can cause it to flake apart at any location within the PB piping system. Minor fractures can deepen over time and eventually work their way to the pipe’s exterior, allowing water to escape. Some manufacturers, however, claim that the majority of leaks occur at joints and unions. Improperly installed unions are where a leak would likely appear. Despite this contention, class-action lawsuits filed against PB manufacturers have successfully resulted in payouts to homeowners reaching $1 billion. 

 Polybutylene Pipes Should Be Replaced

Although no regulations require replacing polybutylene piping with other material, many plumbers recommend doing this for several thousand dollars. PB pipes installed behind sheetrock can leak unnoticed for long periods and cause mold and water damage. Leaking can happen without warning and can result in flooding and severe damage to a home’s interior if it is not immediately stopped. InterNACHI believes it is far cheaper to replace polybutylene pipes before they fail and release their contents onto floors, appliances, and furniture. They can also reduce a home’s value or prolong its time on the market. Homeowners might face higher insurance premiums or be denied coverage entirely. For homeowners concerned about this problem and wish to replace the PB piping in their home with copper or other material, companies specialize in this type of work.

 Identifying Polybutylene

An inspector can use the following tips to identify polybutylene plumbing. Polybutylene pipes are:

  • usually stamped with the code “PB2110.”
  • flexible and sometimes curved, unlike rigid piping materials such as copper
  • not used for waste, drain, or vent piping
  • Most commonly grey in color, but they can also be white, silver, black or blue. Blue PB is used primarily outdoors and should only be used to carry cold water. Inspectors should know that black or white pipes might not be polybutylene (they might be polyethylene or PVC, respectively). Also, PB color is somewhat region-dependant. For instance, experienced home inspectors in California might never come across grey PB, while it is quite common elsewhere.
  • Piping is ½” to 1″ in diameter.

Polybutylene pipes can be in a home’s interior or exterior in any of the following locations:

 Interior:

  • protruding from walls to feed sinks and toilets;
  • running across the ceiling in unfinished basements;
  • near the water heater.

Exterior:

  • entering the home through the basement wall;
  • at the water meter;
  • at the main water shut-off valve.

Note:

  • Home inspectors are not required to note the presence of polybutylene, nor should tests for weaknesses be performed. Any deterioration of polybutylene pipes happens from within and cannot be detected without turning off the water and dismantling the pipe, which is far beyond the standards of practice of home inspection.
  • Inspectors should check an entire pipe for PB, not just a portion of it. Some copper piping systems have been found to use PB at junctures. A typical example of this union is PB pipe connecting with copper “stub outs” that feed bathroom fixtures. 

Other piping materials not to be confused with PB:

  • PEX: Cross-linked polyethylene is common in radiant-heating systems. PEX can be black, blue, or red, is more easily coiled, and more flexible than PB. It can also withstand higher temperatures than polyethylene.
  • PVC: Polyvinyl Chloride is a popular building material commonly used in residential plumbing. CPVC is derived from PVC and is also used in plumbing. Both appear white or off-white and can be flexible or rigid.
  • Polyethylene: This material is flexible and black.
  • Copper: Copper is a metal that should never be confused with PB.

 If in doubt, contact a licensed plumber to determine whether or not a pipe is made from PB.

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