​The presence of polybutylene pipe can severely affect a home’s value on the real estate market. Poly pipe generally takes 10-15 years to begin to show signs of severe deterioration; therefore it is important to know what problems can be caused by its presence, and what can be done about it before it poses a risk.
Problems With Polybutylene
Although some poly piping problems stem from improper installation, most complaints are with the integrity of the piping itself. Polybutylene pipe is known to deteriorate due to contact with oxidants normally found in public water supplies. The failure can occur in the plastic fittings or in the pipe itself. A main concern regarding poly pipe is that, since the oxidants are carried in the water, the pipe deteriorates from the inside. This makes it very difficult to determine if the pipe is truly in good condition. Most home inspectors cannot give a reliable assessment on the condition of poly piping unless there is a visible problem with the exterior of the pipe or its installation. In addition, when a leak occurs, it may be extremely severe because the deterioration occurs from within.
Poly pipe leaks are unpredictable and there are no symptoms to warn of an impending leak. Some factors that affect polybutylene piping adversely can include:

• Poor installation
• Water quality
• Pipe age
• Chlorine levels
• Deterioration of fittings (both metal and plastic)

When polybutylene pipe reacts with the oxidants in normal tapwater, it becomes brittle, sometimes scaling or flaking. This results in a fracturing of the interior surface of the pipe, which allows for more deterioration. Eventually the pipe will begin to leak, causing damage throughout a home. Poly pipe with plastic fittings or with metal fittings will eventually incur damage; poly piping is not a reliable piping under any circumstances. If a pipe has been leaking for some time without the knowledge of a homeowner, severe structural damage to the home can result, making repairs extremely difficult.
Damage from polybutylene pipe leaks can be expensive, in some cases more than the original cost of the house. Insurance companies sometimes cancel or refuse policies for homes with known poly piping problems, and it is difficult to market a home that has such an unreliable plumbing system.
Identification
The most effective way of identifying polybutylene pipe is to have your plumbing inspected by a licensed professional. While inspectors generally cannot determine if there is deterioration in poly piping, licensed plumbers can confirm if you have poly piping installed in your home. Typical characteristics of polubutylene piping include:

• • Blue, gray, or black color
  • ½" to 1" diameter

Poly piping can be used anywhere in the home’s plumbing system – usually its presence can be ascertained by checking the attachments under household sinks, near hot water heaters, or leading into toilets. Following is a list of common places you may inspect for the presence of poly piping:
Interior

• • Entering the water heater
  • Crossing basement ceilings
  • Feeding sinks, toilets, and bathtubs

Exterior

• • Entering the home through basement walls, etc
  • Attached to your home’s main water shutoff valve
  • Attached to your home’s water meter (often a copper pipe at a water meter will be attached to poly pipe somewhere underground, so it is wise to check both ends of the pipe)

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Note: Not all polybutylene piping systems use polybutylene fittings; some use copper. Therefore, if you see copper fittings on a pipe, it does not indicate that you do not have poly piping.
Another important area where poly piping may have been installed is the incoming water supply line to you house. If this incoming pipe is a light blue plastic pipe, it is likely that you have a type of poly pipe informally called "Big Blue". This pipe is extremely prone to failure and unexpected bursting. If you have this type of pipe as an incoming water supply line, it is recommended that you have it replaced as soon as possible.