Replace Polybutylene with PEX: The Ultimate Guide

If you own a home built between 1978 and 1995, you might be sitting on a ticking time bomb: polybutylene piping. These gray plastic pipes were once hailed as the “pipe of the future,” but we now know they are prone to sudden, catastrophic failures due to chemical degradation. If you are noticing pinhole leaks or discolored water, it is not just a repair issue; it is a systemic failure. Knowing how to change plumbing systems from polybutylene to PEX is the most critical investment you can make to safeguard your property value and peace of mind. This guide will walk you through the process, helping you decide whether to tackle this complex job yourself or hire a professional.

Why You Must Replace Polybutylene Pipes Immediately

Before diving into the how, it is vital to understand the why. Polybutylene (PB) pipes were installed in millions of US homes because they were cheap and easy to install. However, they react negatively to oxidants found in public water supplies, such as chlorine.

Over time, this reaction causes the pipe walls to become brittle and flaky on the inside. This process, known as oxidative degradation, leads to micro-fractures that eventually burst without warning.

The Risk Factor

• Unpredictable Failure: Unlike copper, which usually leaks at joints, PB pipes can burst anywhere along the wall.
• Insurance Issues: Many insurance companies now refuse to cover homes with active polybutylene plumbing or charge significantly higher premiums.
• Resale Value: Homes with known PB plumbing often fail inspection or require price reductions equivalent to the cost of repiping.

According to industry data, the failure rate of polybutylene plumbing increases significantly after 20–25 years. Since most of these installations occurred decades ago, the majority of these systems are now well past their expected lifespan.

PEX vs. Polybutylene: A Clear Comparison

Why is Cross-linked Polyethylene (PEX) the gold standard for replacement? PEX shares the flexibility of polybutylene but lacks its chemical vulnerabilities. It is resistant to scale and chlorine, does not corrode, and can expand if water freezes, reducing the risk of bursting.

For more detailed chemical properties and historical context on plastic piping materials, you can refer to the technical overview on Wikipedia’s page on Polybutylene.

Step-by-Step: How To Change Plumbing Systems From Polybutaline To Pex

Replacing your plumbing is a major project. Below is the professional workflow used by licensed plumbers. Note: If you are not comfortable working with main water lines or soldering/crimping, please hire a licensed professional.

Step 1: Assessment and Permitting

Before cutting a single pipe, check your local building codes. Most jurisdictions in the US require a permit for whole-house repiping.

1. Inspect the Layout: Identify where the main water line enters the house and trace the PB pipes to all fixtures.
2. Check for Asbestos: In older homes, pipe insulation or wall textures may contain asbestos. Test before disturbing walls.
3. Obtain Permits: Submit your plan to the local building department. This ensures your work is inspected and insurable.

Step 2: Gather Tools and Materials

You will need specific tools for PEX installation. Do not skimp on quality here.

• PEX Tubing: Ensure it is NSF-rated for potable water. Use Red for hot lines and Blue for cold lines (or white with markings).
• Fittings: Brass or Plastic PEX fittings (elbows, tees, couplings).
• Crimping Tool: A reliable PEX crimping tool compatible with your ring size (usually 3/8″ or 1/2″).
• Go/No-Go Gauge: Essential for verifying crimp quality.
• Pipe Cutter: A sharp PEX cutter for clean, square cuts.
• Deburring Tool: To smooth edges after cutting.
• SharkBite Push-to-Connect Fittings: Useful for temporary connections or tight spaces where crimping is difficult.

Step 3: Shut Off Water and Drain System

1. Locate the main water shut-off valve. Turn it clockwise until tight.
2. Open the highest faucet in your home (e.g., second-floor bath) and the lowest faucet (e.g., basement sink or outdoor spigot) to drain the system completely.
3. Use an air compressor to blow out remaining water if necessary, ensuring dry working conditions.

Step 4: Removal of Polybutylene Pipes

This is the most labor-intensive phase.

1. Cut and Remove: Cut the PB pipes close to the fittings. Do not try to pull long sections through walls if they are stuck; it may damage drywall.
2. Leave Stubs if Necessary: If a pipe runs through a finished wall and cannot be easily pulled out, cap the old PB pipe securely inside the wall and run new PEX alongside it or through a new route.
3. Disposal: Check local regulations for disposing of plastic piping.

Step 5: Installing the New PEX System

There are two main methods: Home Run (Manifold) and Trunk and Branch. The Home Run method is preferred for modern efficiency.

The Home Run Method:

1. Install Manifold: Place a PEX manifold near the main water entry. This acts as the distribution hub.
2. Run Lines: Run individual continuous lines of PEX from the manifold to each fixture (sink, toilet, shower). Avoid splices inside walls.
3. Secure Pipes: Use PEX hangers every 32 inches on horizontal runs and every 6 feet on vertical runs. Allow slight slack for expansion.
4. Protect from Abrasion: Where PEX passes through wood studs or joists, use protective nail plates or grommets to prevent chafing.

Connection Technique:

1. Cut the PEX tube squarely.
2. Slide a copper crimp ring onto the tube.
3. Insert the fitting fully into the tube.
4. Position the crimp tool over the ring and squeeze firmly.
5. Crucial Step: Use the Go/No-Go Gauge to test the crimp. If it fails, cut the end and redo it. A bad crimp is a future leak.

Step 6: Pressure Testing

Never close up walls without testing.

1. Close all fixture valves.
2. Attach a pressure gauge to a hose bib or washing machine outlet.
3. Pressurize the system to 100 PSI (or per local code, typically 1.5x operating pressure).
4. Let it sit for 2–4 hours. If the pressure drops, you have a leak. Check every connection.
5. Once stable, flush the lines to remove debris.

Cost Breakdown: DIY vs. Professional Hiring

Understanding the financial implication is part of learning how to change plumbing systems from polybutaline to Pex.

• DIY Cost: $2,000 – $4,000.
  • Includes materials (PEX, fittings, manifold) and tool rental/purchase.
  • Risk: No warranty on labor; potential for costly errors.
• Professional Cost: $4,000 – $15,000+.
  • Depends on home size, number of stories, and accessibility.
  • Includes labor, permits, inspections, and warranty.
  • Benefit: Insurance-backed warranty and code compliance.

Expert Tip: If your home has multiple stories or slab foundations, the complexity increases drastically. In these cases, professional equipment like tunneling tools may be required, making DIY impractical.

FAQ Section

1. Can I connect PEX directly to existing polybutylene pipes?

Technically, yes, using transition fittings (such as SharkBite push-to-connect fittings designed for PB-to-PEX). However, this is not recommended for a permanent solution. Since the PB pipe is already degraded, leaving it in place retains the risk of failure. It is best to remove as much PB as possible.

2. Do I need a plumber to replace polybutylene with PEX?

While DIY is legal in many areas, repiping is complex. Mistakes can cause massive water damage. If you are not experienced with plumbing codes and pressure testing, hiring a licensed plumber is strongly advised. Additionally, some insurance companies require professional certification for coverage.

3. How long does it take to repipe a house?

For a professional crew, a standard 2,000 sq. ft. home takes 2–5 days. For a DIYer, expect 1–3 weeks depending on your skill level and available time. Accessibility (crawl spaces vs. slab foundation) heavily influences timelines.

4. Will replacing pipes damage my drywall?

Minimal damage occurs if plumbers use “fish tapes” to pull new lines through existing cavities. However, some access holes are inevitable. Budget for minor drywall patching and painting. Some homeowners choose to repaint the entire room for a seamless finish.

5. Is PEX better than Copper for repiping?

For most residential applications, yes. PEX is cheaper, faster to install, resistant to freezing bursts, and quieter (dampens water hammer). Copper is more expensive and requires soldering, which poses a fire risk during installation. However, copper is still preferred for exterior exposed lines due to UV resistance (PEX degrades in sunlight).

6. Does homeowners insurance cover polybutylene replacement?

Generally, no. Insurance covers sudden and accidental damage, not preventative maintenance or known defective materials. However, some insurers offer discounts if you proactively replace PB with PEX, as it reduces their risk liability. Check with your provider.

Conclusion

Learning how to change plumbing systems from polybutaline to Pex is about more than just swapping plastic tubes; it is about securing the structural integrity and financial value of your home. While the upfront cost of repiping can seem steep, it pales in comparison to the potential devastation of a burst pipe ruining your floors, walls, and belongings.

Whether you choose the DIY route to save on labor or hire a professional for peace of mind, taking action now is crucial. Don’t wait for the first leak to appear.

Found this guide helpful? Share it with your neighbors on Facebook or Nextdoor—many homes in your area might still have these ticking time bombs hidden in their walls. Stay safe and keep your water flowing cleanly!