Polybutylene Piping Problems

Polybutylene is a plastic resin used in manufacturing pipes and fittings from the late 1970s through the mid‑1990s.

Popular for its low cost and easy installation, as many as 10 million buildings and homes across North America opted for this material for their domestic water and, in some cases, fire sprinkler systems. This includes many many low‑ and mid‑rise apartment and condominium properties built at the time.

Use of polybutylene was discontinued after a major class action settlement in 1995.

Why Polybutylene Pipes Fail

Poly’s Defect Problems

The main issue with polybutylene is that it doesn’t handle municipal water well, making it a poor choice for domestic pipes. Polybutylene piping degrades when exposed to typical water treatment chemicals such as chlorine, leading to brittle pipe walls, micro‑fractures, and sudden (often catastrophic) leaks.

Poly’s Age Problems

According to studies by Fannie Mae and HUD, domestic water supply systems in multifamily buildings reach the end of their useful life after 30–50 years. Even if you’re not dealing with major leaks, you should budget for replacing these pipes soon, as major leaks can occur without warning—also leading to potential insurance challenges.

Here are a few of the top questions we get about polybutylene piping.

Poly pipes inside your building are typically gray. Look for them by water heaters, sinks, and toilets. Keep in mind that in some cases, a combination of poly and copper was used. This means that you may see copper pipe, but polybutylene may still be found behind your walls, ceilings, and foundations. A qualified plumber can help to confirm.

Poly was used in domestic supply and fire sprinkler systems.

Poly piping is found in garden-style (low-rise) condominiums and apartment buildings, in addition to single-family homes.

Don’t be fooled if you see poly pipes and think they look fine. These pipes degrade from within, making failure invisible from the outside and difficult to predict. Whether you have poly or you’re not sure, contact a professional to understand what you should do next.

Sometimes, we hear from multifamily owner/operators or condo Boards about their “good poly”—that is, polybutylene piping that hasn’t failed yet. These lucky communities often have water supplied by a well rather than a local municipality, so they haven’t had to deal with poly pipes flaking or peeling due to chlorine. However, at this point, all poly systems are beyond their useful lives, with decades of stress from pressure, temperature, and water flow. (Read more about why “good poly” is a misnomer.)

Based on more than 10 years of SageWater project data (June 2011–March 2022), we see the Fannie Mae and HUD End of Useful Life estimates are accurate, with all 275 multifamily properties that we talked with showing domestic pipes that were failing at 34.5 years on average. The 148 properties we talked with containing poly pipes were failing sooner, at 28.4 years on average.