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Type K vs. Type L vs. Type M Copper Tubing – Which Should You Choose?
August 4, 2025 Accounting ics

Type K vs. Type L vs. Type M Copper Tubing – Which Should You Choose?

Choosing the right copper tubing for your plumbing or HVAC job isn’t always straightforward. One of the most common questions we get is:
“What’s the difference between Type K, Type L, and Type M copper tubing?”
Let’s break it down so you know exactly what to order.

Type K Copper Tubing

  • Thickest wall of the three types
  • Ideal for underground water lines and high-pressure systems
  • Used in both commercial and residential plumbing
  • Available in coils and straight lengths

Pro Tip: Type K is commonly specified by city codes for underground service lines.

Type L Copper Tubing

  • Medium wall thickness
  • Most commonly used for interior plumbing
  • Versatile for hot/cold water lines and HVAC systems
  • Also available in rigid and flexible formats

Pro Tip: Type L strikes the best balance of strength, price, and ease of installation.

Type M Copper Tubing
  • Thinnest wall
  • Used in low-pressure residential plumbing
  • Not approved for some jurisdictions due to its thinner walls
  • Lower cost — good for budget-conscious jobs where code allows
Summary Table
Type Wall Thickness Common Use
K Thickest Underground, high-pressure
L Medium Interior plumbing, HVAC
M Thinnest Budget residential use

Still not sure which type you need?
Visit our collection pages for Type K, Type L, and Type M copper tubing — or contact us and we’ll help you choose the right one.

Previous article ASTM B88 & B280 Explained: Copper Tubing Standards for Plumbing & HVAC

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