Open a wall in any house built since 1950 and you’ll find at least three different pipe materials, each there for a reason that made sense the year it was installed. Types of plumbing pipes in modern American homes fall into six main categories: PEX, copper, PVC, CPVC, ABS, and cast iron. Each has a different cost, lifespan, code-approved use, and failure mode. I’ve replaced miles of bad pipe over twenty years, and here’s what every homeowner should know before opening a wall.
PEX (Cross-Linked Polyethylene)
PEX has dominated new residential construction since the early 2000s for good reasons: it’s flexible, freeze-resistant, fast to install, and cheap. Comes in three types: PEX-A (most flexible, expansion fittings, brand names Uponor and Rehau), PEX-B (slightly stiffer, crimp or clamp fittings, brand names Apollo and SharkBite), and PEX-C (cheapest, less common in residential).
Cost runs $0.50 to $1.20 per linear foot for 1/2-inch tubing, plus $1 to $5 per fitting. Lifespan is 40 to 50 years per manufacturer warranties. Color coding (red for hot, blue for cold) makes troubleshooting easy. Cannot be used outdoors exposed to UV; sheathing or burial is required.
Copper Pipe
Copper was the gold standard from the 1960s through the 1990s and remains code-approved everywhere. Three wall thicknesses are sold: Type M (thinnest, residential supply), Type L (medium, also residential and light commercial), and Type K (thickest, underground and commercial). Type L is the most common upgrade choice for a remodel.
Cost runs $3 to $8 per linear foot for 1/2-inch Type L, with sweat-soldered fittings adding $2 to $7 each. Press fittings (ProPress, RIDGID) cost more upfront but install in seconds with the right tool. Lifespan is 50 to 70 years in good water; aggressive water (low pH, high chloride) shortens that to 20 to 30 years and causes pinhole leaks. Solid recyclable scrap value when removed.
PVC (Polyvinyl Chloride)
White PVC is the workhorse for cold-water supply lines (in some jurisdictions), drain-waste-vent (DWV), and irrigation. It comes in schedule 40 (standard) and schedule 80 (thicker, higher pressure). PVC is not approved for hot water in most jurisdictions because it deforms above 140°F.
Cost runs $0.40 to $1.50 per linear foot for 2-inch schedule 40 DWV, with fittings at $0.50 to $4 each. Lifespan exceeds 100 years buried; UV exposure cracks it within 5 to 10 years above ground. Joints are solvent-welded with primer (purple) and cement (clear, blue, or gray); skip the primer and your joint will leak within a year.
CPVC (Chlorinated Polyvinyl Chloride)
Cream or beige in color, CPVC handles both hot and cold supply lines up to 200°F. It’s stiffer than PEX and more expensive than PVC. FlowGuard Gold is the dominant brand in U.S. residential.
Cost runs $0.65 to $1.40 per linear foot for 1/2-inch, with fittings at $0.75 to $3 each. Lifespan is 50 to 75 years. CPVC becomes brittle with age and can crack if struck or over-tightened, especially in unconditioned attics where it sees temperature swings. Use only manufacturer-approved cement and primer; standard PVC cement is not rated for CPVC.
ABS (Acrylonitrile Butadiene Styrene)
Black ABS pipe is the West Coast equivalent to white PVC for DWV. Some jurisdictions allow only ABS, others only PVC, and a handful allow either. Schedule 40 ABS is the standard residential drain pipe in California, Oregon, and Washington.
Cost runs $0.50 to $1.60 per linear foot for 2-inch, with fittings at $0.60 to $4 each. Lifespan exceeds 75 years. ABS is jointed with one-step black cement (no primer required) and resists impact better than PVC, which matters in cold-climate basements where pipes can get bumped.
Cast Iron
Cast iron drain lines were standard in homes built before 1975 and are still spec’d for multifamily and commercial buildings because they dampen drain noise dramatically. A flushing toilet upstairs is barely audible through cast iron; with PVC, you hear every gurgle.
Cost runs $9 to $20 per linear foot for 3-inch hubless, plus $25 to $80 per no-hub band. Lifespan is 75 to 100 years inside walls; buried below grade, corrosion can eat through the bottom of the pipe in 50 to 70 years. Cutting cast iron requires a snap cutter or a diamond-blade cut-off saw; not a casual DIY job.
Galvanized Steel (Mostly Legacy)
Galvanized supply pipes were standard from the 1900s to the 1960s and are still found in pre-war homes. They corrode internally, restrict flow, and leach lead from old joints. If you find galvanized supply lines in a 1950s house, plan to replace them; flow at fixtures will be measurably worse than copper or PEX, and the corrosion never reverses.
Cost to remove and replace a typical 1950s home’s galvanized supply with PEX runs $4,500 to $12,000 depending on access. The water quality and pressure improvement is immediate.
Choosing the Right Pipe for the Job
Match the pipe to the application:
- Hot and cold supply, new construction or remodel: PEX-A or PEX-B
- Hot and cold supply, premium or commercial: Type L copper
- DWV inside the home: PVC or ABS depending on local code
- DWV in walls separating living spaces: cast iron for sound reduction
- Underground main water supply: Type K copper or PEX-A in a sleeve
- Outdoor irrigation: schedule 40 PVC or polyethylene tubing
- Gas lines: black iron, CSST (corrugated stainless), or copper depending on code; never PEX
Common Pitfalls
- Mixing copper and galvanized without a dielectric union; galvanic corrosion eats both within 5 to 10 years.
- Using PVC for hot water; deformation and joint failure are guaranteed.
- Skipping primer on PVC joints; the joint will weep within a year.
- Over-tightening PEX crimp or clamp rings; cracking the fitting and getting a delayed leak.
- Running PEX exposed in attics with sunlight reaching it; UV degrades the polymer in months.
- Burying ABS or PVC drain pipe without proper bedding sand; rocks puncture the pipe under load.
Cost Comparison Summary
For a 2,000 sq ft home repipe of supply lines only, here’s the typical installed cost spread:
- PEX: $4,000 to $7,500
- CPVC: $5,000 to $9,000
- Copper Type L: $9,000 to $18,000
For DWV replacement, costs depend heavily on access and depth, ranging from $3,500 for a single-bath retrofit to $25,000+ for a full house with cast iron under a slab.
When to Call a Plumber
DIYers can handle PEX runs, simple copper sweating, and PVC drain extensions in accessible locations. Hire a licensed plumber for any work involving the main water shutoff, gas lines, water heater connections, sewer lateral repair, or anything inside a load-bearing wall. Permits and inspections protect both safety and resale value; a permitted repipe can add $5,000 to $15,000 to a home’s appraised value, while unpermitted work can scare off buyers.
