PEX vs Copper Pipe: Which Should You Use for a Repipe?
PEX costs $0.50-0.80/ft vs copper at $2.50-4/ft, bends around corners without fittings, and skips the torch. Here is how to choose for your repipe.
Quick answer: PEX costs $0.50-0.80 per foot versus copper at $2.50-4.00 per foot, bends around corners without fittings, and requires no torch. For a typical whole-house repipe done by a homeowner, PEX is the clear practical choice. Copper lasts 50-70 years, handles UV exposure, and is required in a handful of local codes; PEX is rated 25-50 years and cannot stay in sunlight. If the job is indoors in conditioned space, PEX. If it is outdoors, near a heat source like a water heater flue, or in a jurisdiction that still requires copper for main supply lines, copper.
Copper has been the standard residential plumbing material since the 1960s. PEX (cross-linked polyethylene) started appearing in US homes in the 1990s and has become the dominant choice for new construction and repipe work in the last decade. Both carry potable water safely. The differences come down to cost, installation method, longevity, and a few situational limits that actually matter.
What You Are Choosing Between
PEX is flexible plastic tubing sold in straight sticks or on coils. The most common types are PEX-A (most flexible, the Uponor/Wirsbo product; works with expansion-style fittings), PEX-B (stiffer, sold under dozens of brands, works with crimp and clamp fittings), and PEX-C (less common, not worth hunting down). For residential repipe, PEX-B in 1/2-inch and 3/4-inch diameters covers 90% of the job.
Copper is rigid metal tube sold in 10-foot straight sticks. Type M (thin-walled) is what goes in most residential supply lines. Type L (thicker walls) is used in commercial work and occasionally in residential where codes require it. Copper requires soldering with a propane or MAPP torch, lead-free solder, and flux to make watertight joints.
Cost
This is where the difference becomes hard to argue with.
PEX-B tubing runs $0.50-0.80 per foot for 1/2-inch, and $0.80-1.20 per foot for 3/4-inch. Fittings (brass crimp elbow, tee, coupling) cost $1.50-3.00 each. A basic crimp tool runs $60-100 at any home center.
Copper Type M runs $2.50-4.00 per foot for 1/2-inch, and $4.00-6.00 per foot for 3/4-inch. Copper prices track the commodity market and can swing 20-30% in a year. Fittings for copper (elbows, tees, couplings) cost $3.00-8.00 each. A propane setup costs $40-60; if you need MAPP gas for faster work, add another $20-30.
For a typical 1,200 square foot house requiring 350 linear feet of 1/2-inch pipe and 100 feet of 3/4-inch for main runs:
PEX materials: roughly $300-400 for tubing plus $100-150 for fittings and a crimp tool. Total materials: $400-550.
Copper materials: roughly $950-1,500 for tubing plus $200-350 for fittings, flux, and solder. Total materials: $1,150-1,850.
That gap widens when you factor in labor. Plumbers charge more for copper because it takes longer to install. A professional repipe in PEX typically runs $3,000-5,000 for a standard home. The same job in copper often runs $6,000-12,000.
Installation
PEX: The tube bends. That sounds simple, but it changes everything about how a repipe goes. You run a continuous length of PEX from the manifold to a fixture, routing it through framing holes without stopping to sweat a fitting at every corner. Fewer fittings means fewer potential leak points. Connections use a crimp ring and a cheap tool, or a push-to-connect SharkBite fitting if you want to work even faster (SharkBites cost $5-8 each vs $2-3 for a crimp fitting, but no tools required). The whole process is learnable in about 30 minutes.
Copper: Rigid. Every change of direction needs an elbow and two soldered joints. Soldering requires keeping the joint dry (water vapor kills a solder joint), heating the fitting correctly so solder flows by capillary action rather than just puddling, and not overheating the flux to the point where it turns black and stops working. It takes practice. A first-time DIYer soldering copper supply lines is going to produce a few bad joints. Catching a pinhole leak behind a wall three years later is how that story ends for some people.
Before any plumbing work, shut off the water to the house at the main shutoff valve and drain the lines. That step is the same regardless of which material you choose.
Durability
Copper has the longer track record. Copper supply lines installed in the 1950s and 1960s are still in service in older homes. When installed correctly in water with appropriate chemistry (neutral pH, not aggressive), copper routinely lasts 50-70 years. Some installations push beyond that.
PEX carries a 25-50 year rating per NSF/ANSI 358-1, the standard for PEX tubing used in plumbing systems. The material has been used in Europe since the 1970s and in US homes since the mid-1990s. No large body of failed 30-year-old PEX exists yet because the material simply has not been in the ground that long in North America. The rating is testing-based, not field-verified. Whether that 50-year ceiling is accurate, conservative, or optimistic is genuinely unknown.
Hard water accelerates copper pinhole corrosion, particularly in high-chloramine municipal water (the disinfectant the majority of US water utilities now use instead of chlorine). Phoenix, Denver, and most of the Southwest have documented higher rates of copper pinhole failures than areas with softer water. If you have low water pressure already and your home has copper pipe in the walls, early corrosion narrowing the pipe bore is worth investigating.
PEX is essentially immune to the corrosion and pitting that copper faces in aggressive water. It is also much more tolerant of freezing: the tube expands rather than splitting, which means a freeze event that would burst a copper line often just stresses PEX and does not cause a failure. Not freeze-proof, but substantially more forgiving.
Where Each Falls Short
PEX limits:
- Cannot be used where it will be exposed to UV light (outdoors, near windows). UV degrades the material over time. Any outdoor run needs to be sheathed in UV-rated conduit or converted to copper for the exposed section.
- Cannot be used near open flame or excessive heat. Keep PEX away from water heater flues, boiler exhaust, and any heat source above 200 degrees F.
- Some jurisdictions and some building inspectors still prefer copper for certain applications, particularly main supply lines entering the building. Check your local code before starting a full repipe.
- Copper scrap has resale value. PEX is essentially worthless as scrap.
Copper limits:
- Costs substantially more in both material and labor.
- Requires soldering skill to install without callbacks.
- Prone to pinhole corrosion in high-chloramine water systems, particularly in thin-wall Type M in aggressive chemistry.
- Expands and contracts more than PEX with temperature cycling, which over decades can work joints loose in certain installation configurations.
Where PEX Wins
Any repipe done in conditioned space by a homeowner who wants to learn the skill once and not hire out the full job. The crimp tool pays for itself on the first 10 fittings, and the material cost savings are real. A homeowner who needs to replace a bathroom faucet and wants to run new 1/2-inch supply lines at the same time will find PEX significantly more approachable than sweating copper in a tight cabinet space.
After a tankless water heater installation where a plumber has already replumbed the primary runs, extending with PEX for branch lines to individual fixtures is a natural follow-on project.
Where Copper Wins
Outdoor runs. Above-ground sections near heat sources. Any application where the pipe will see sunlight. Cases where the local inspector specifically calls for copper.
Some homeowners also prefer copper for mechanical rooms and utility spaces where the pipe is visible, since copper looks better than PEX and tends to stay neater over time. It is a legitimate preference.
If you have hard water and are concerned about long-term reliability, the corrosion resistance of PEX is worth considering, particularly if an older copper system has already shown signs of pitting.
Common Mistakes
Running PEX in the wrong place. Outdoors, under a slab exposed to soil without UV protection, or too close to a water heater flue are the common errors. Read the installation instructions for the specific PEX brand. General guidance covers 80% of it; the remaining 20% is brand-specific and sometimes code-specific.
Using SharkBite fittings everywhere. SharkBite push-to-connect fittings are excellent for isolated repairs and for connections made in inaccessible locations. They are not the economical choice for a full repipe. A full house done in SharkBites will run $300-500 in fittings alone versus $80-120 in crimp fittings. Buy the crimp tool.
Not pressure-testing before closing walls. Run the system to pressure, check every fitting, and leave it for two hours before drywalling. A single bad crimp behind a wall costs far more to find later than the time it takes to inspect now.
Undersizing the main supply run. Running 1/2-inch pipe as the main trunk and branching to individual fixtures from there creates pressure drop when multiple fixtures run simultaneously. The main runs serving multiple bathrooms or a kitchen plus laundry should be 3/4-inch. Branch lines to individual fixtures drop to 1/2-inch at the fixture.
Mixing PEX and copper without transition fittings. If you are extending an existing copper system with PEX, you need a copper-to-PEX adapter fitting at the transition point. These are inexpensive and widely available. Do not try to crimp PEX directly to copper tubing.
When to Call a Pro
The main shutoff itself, the supply line entering the house from the meter, and anything involving a gas line. If a repipe requires cutting into the main line before the first shutoff, that work is done live, meaning water service to the house is off at the street, and a meter key is needed to restore it. Most municipal water authorities require a licensed plumber for service line work. On the electrical side: if you are running near ROMEX or knob-and-tube wiring while you work, stop and deal with the wiring separately before adding a wet trade to the same wall space.
FAQ
Is PEX as good as copper for drinking water? Both are NSF/ANSI 61 certified for potable water when properly manufactured. NSF 61 is the health-effects standard for materials that contact drinking water, and PEX tubing carrying that listing has passed the same testing as copper. Early PEX formulations had concerns about MTBE leaching, but modern NSF-61 certified tubing does not have that problem. Buy tubing with the NSF mark on it.
Can I use PEX for hot water lines? Yes. PEX is rated for continuous service up to 180 degrees F and 100 PSI. Standard residential water heaters are set at 120-140 degrees F, which puts hot supply lines comfortably within PEX’s operating range. PEX is used for both hot and cold supply, as well as radiant floor heating systems at similar temperatures.
Do I need a permit to repipe my house? In most jurisdictions, yes. Plumbing permits exist so an inspector can verify the work meets code before walls close. The EPA’s lead-free plumbing requirements apply to all new and replacement residential plumbing; both certified copper and NSF-certified PEX meet the standard. Doing unpermitted repipe work is a problem when you sell the house or make an insurance claim. Pull the permit; the fee is typically $50-150 and the inspection is a single walkthrough before drywalling.
How long does a whole-house PEX repipe take? A professional crew typically completes a 1,200-1,500 square foot house in 1-2 days. A capable DIYer working weekends might spend 2-3 weekends, with most time going to cutting access panels, routing through framing, and restoring walls after rough-in inspection.
Does PEX freeze and burst like copper? PEX handles freezing better than copper but is not immune. The tube expands significantly under freezing pressure, which is why PEX survives freeze events that would split copper. If the freeze is severe enough and the water has nowhere to expand, PEX can fail too, usually at a fitting rather than mid-pipe. The standard advice applies: insulate pipes in unconditioned spaces, keep the heat on above 55 degrees F during cold snaps.
Can I connect PEX directly to my water heater? Most water heater manufacturers and plumbing codes require the first 18-24 inches of pipe off the water heater connections to be copper, to handle the higher temperatures near the tank. After that transition section, PEX is fine. Check the water heater installation manual for the specific manufacturer’s requirement.
What is the difference between PEX-A, PEX-B, and PEX-C? The letters refer to the cross-linking method used during manufacturing, not quality levels. PEX-A (Uponor/Wirsbo) is the most flexible and works with expansion-style fittings; you expand the end of the tube with an expansion tool, push on the fitting, and the tube contracts to form a tight seal. PEX-B is stiffer, the most widely sold type, and works with crimp rings and clamp rings. PEX-C is made by a third method and is less common in residential applications. For a DIY repipe, PEX-B with crimp fittings is the right starting point unless you already own expansion tooling.
Is copper ever required by code these days? Rarely for interior supply lines. A handful of jurisdictions still specify copper for certain applications, but the International Residential Code and Uniform Plumbing Code both permit PEX for potable water supply throughout a dwelling. Your local code might add restrictions, so confirm with the building department before buying materials.