Type L vs Type M Copper in Newport Beach Homes: Wall Thickness, Corrosion and Repipe Choices
Copper pipe comes in different wall thicknesses. How Type K, L and M differ, which ones show up in Newport Beach homes, why thin copper pinholes, and when PEX-A is…
Newport Beach homeowners often ask for copper by name. It has a long track record, and many homes in Corona del Mar, Newport Heights, Eastbluff and on Balboa Island were plumbed with it decades ago. But "copper" is not one product. Copper water tube is made in several wall thicknesses, and the type in your walls has a lot to do with how it has aged.
The three common types
Copper tube for water is sold as Type K, Type L and Type M. For a given size, the outside diameter is the same; the difference is wall thickness.
- Type K has the thickest wall. It is used mainly for underground service lines
- Type L has a medium wall. It is the common choice for interior supply lines where durability matters
- Type M has the thinnest wall. It is lighter and was widely used in residential construction
Rigid copper is usually printed with a colored stripe: green for K, blue for L and red for M. Look along an exposed section near the water heater or under a sink.
Why thin copper fails sooner
Copper corrodes slowly from the inside, and the rate depends on water chemistry, velocity, temperature and how the joints were made. A thinner wall simply has less metal to lose before a pinhole forms. Type M lines in hot water loops, at elbows and near fittings are where we see the most leaks. Many Newport Beach homes built from the 1950s through the 1980s used Type M for interior lines.
Coastal factors
Homes near the bay and the beach face salt air on exterior piping and hose connections. Inside, the main concerns are water chemistry and age. Homes on Balboa Island and the Peninsula also have tight lots and shared walls, so a leak can affect neighbors quickly.
If you want copper again
Some homeowners prefer to repipe with copper. If you do, Type L is the better choice for interior supply lines because the thicker wall gives more margin. Copper repipes take more wall access and more soldered joints than PEX.
Why we usually recommend PEX-A
For most Newport Beach homes, Repipe OC recommends PEX-A (Uponor/Wirsbo expansion, ASTM F1960):
- It does not pinhole the way thin copper does
- It handles mineral-heavy water without building scale at joints
- Flexible runs mean fewer fittings and smaller wall openings
- Expansion fittings keep a full flow path
Both are code-approved. We explain the trade-offs and let you choose.
How to know what you have
If you are not sure, we can identify the pipe type and wall thickness during an estimate and look for corrosion at the spots that fail first.
Related reading
See PEX-A vs copper for Newport Beach repipes and signs you need a whole house repipe. Neighbors can visit our Costa Mesa, Irvine and Laguna Beach sites, and every city we serve is listed at repipeinc.com.
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Repipe OC, 23821 Hillhurst Drive, Laguna Niguel, CA 92677, (949) 524-2362, CSLB #1087885 C-36.
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Written by Repipe OC · CSLB #1087885 C-36 · 23821 Hillhurst Drive, Laguna Niguel, CA 92677 · (949) 524-2362