Copper Piping
Updated February 20, 2026
The traditional standard for residential plumbing. Durable, bacteriostatic, and long-lasting. Available in rigid and flexible (soft) forms.
Overview
Copper has been the standard for residential water supply lines for over 70 years. Type M (thin wall) is standard for residential supply. Type L (medium wall) is used for commercial and outdoor burial. Copper is durable, corrosion-resistant in most water conditions, bacteriostatic (inhibits bacterial growth), and fully recyclable. Joints are soldered (sweated) with flux and lead-free solder, or connected with push-fit fittings. The main drawback: cost. Copper is significantly more expensive than PEX and requires soldering skill or push-fit fittings for connections.
Pros & Cons
- Extremely durable
- Bacteriostatic
- Recyclable
- UV resistant
- Expensive
- Requires soldering
- Can corrode in acidic water
- Freezing can burst
Key Features
- Proven 50+ year lifespan in residential water supply applications
- Bacteriostatic -- inhibits bacterial growth inside the pipe
- Handles high temperatures and UV exposure (can be used outdoors)
- Fully recyclable -- has scrap value at end of life
- Rigid pipe maintains shape and supports itself between hangers
Sizing & Selection
Residential supply lines are typically 3/4 inch (main runs) and 1/2 inch (branch lines to fixtures). Type M is standard wall thickness for interior residential. Type L for underground, exterior, or commercial. Measure outside diameter (OD) -- 1/2 inch copper has 5/8 inch OD, 3/4 inch has 7/8 inch OD. Fittings are sized by nominal pipe size, not OD.
Installation
Cut with a tube cutter (not a hacksaw for clean cuts). Deburr inside and outside. Clean both pipe end and fitting socket with emery cloth until shiny. Apply flux, assemble, and solder with lead-free solder and a propane torch. Push-fit fittings (SharkBite) eliminate soldering entirely -- cut, deburr, push in. Copper must be supported with hangers every 6-8 feet on horizontal runs.
Maintenance
- Inspect exposed copper annually for green patina (normal) vs. pinhole leaks (green crusty spots with dripping).
- In aggressive water (low pH, high chlorine), copper corrodes faster. Test water annually if you notice blue-green staining in sinks.
- Insulate copper pipes in unheated spaces -- copper conducts cold and freezes faster than plastic pipe.
- Dielectric unions required where copper connects to galvanized steel -- prevents galvanic corrosion.
Buying Tips
- Type M is sufficient for all residential interior supply lines. Do not overspend on Type L unless code requires it.
- Buy copper in 10-foot sticks. Pre-measure and plan your layout to minimize waste -- copper is expensive.
- Lead-free solder is required by code for all potable water systems. Do not use 50/50 tin-lead solder.
- Push-fit fittings cost more per connection than soldering but save hours of labor. Use them for repairs and tight spaces.
- Copper prices fluctuate with commodity markets. Check current prices before budgeting a repipe project.