Type L vs Type M Copper: Which Pipe Is Better for Repiping?

Type L copper is thicker, stronger, and more durable than Type M copper. Type M is thinner and cheaper. For a whole-home repipe, Type L is usually the better copper choice because a repipe is not something homeowners want to do twice.

What Is Type L Copper?

Type L copper has a thicker wall than Type M copper. It is commonly used for residential water supply lines and is considered a stronger option for long-term performance. Type L is often identified by blue markings. Homeowners usually choose Type L when they want a more durable copper repipe.

What Is Type M Copper?

Type M copper is thinner and less expensive. It is often identified by red markings. Type M may be allowed in some indoor residential applications depending on local code, but because it has thinner walls, it has less material protecting the pipe over time. That matters when pressure, water chemistry, and corrosion enter the picture.

Why Thickness Matters

Pipe wall thickness affects strength, pressure resistance, long-term durability, corrosion tolerance, and leak risk. When corrosion happens inside copper pipe, it slowly eats away at the pipe wall. A thicker pipe gives the system more material before failure. Type L is not indestructible, but it gives the homeowner a stronger system than Type M.

Type L vs Type M Comparison

Which Copper Should You Use for a Repipe?

If a homeowner wants copper, Type L is usually the better repipe choice. Because if walls are being opened, the system is being replaced, and the goal is long-term peace of mind, it makes sense to use the stronger copper option. Type M may save money upfront, but Type L usually makes more sense for a full-home repipe.

Copper vs PEX

Many homeowners comparing Type L and Type M are also comparing copper against PEX. Copper is durable, rigid, more expensive, and labor-intensive. PEX is flexible, more affordable, faster to install, corrosion-resistant, and easier to route through walls, ceilings, and attic spaces. Neither option is always right for every home — a good repipe quote should explain both clearly.

Frequently Asked Questions

Is Type L better than Type M?

Yes. Type L is thicker and generally more durable.

Is Type M copper bad?

Not always, but it is thinner and usually not the first choice for a high-quality repipe.

What type of copper is best for repiping?

Type L is usually preferred for long-term durability.

Is copper better than PEX?

Not always. Copper is premium and durable, while PEX is flexible and more cost-effective.