What Is Involved When Repiping a House?

Repiping a house means replacing the old plumbing system with new piping throughout the structure. This can include water supply lines, drain and sewer piping, and gas lines depending on the condition of the home.

The process involves planning, material selection, pipe sizing, controlled access openings, installation, testing, inspection, and final patching.

Step 1: System Evaluation

The first step is inspecting the existing plumbing. This includes identifying pipe material, checking for leaks, testing water pressure, and counting total fixtures.

• Check incoming water pressure
• Measure developed pipe length
• Count fixture units
• Evaluate drain condition
• Assess gas appliance demand

This determines what needs to be replaced and how the new system must be designed.

Step 2: Choosing the Right Materials

Water Line Materials

• PEX A
• PEX B
• Copper Type L

Water pipe sizing is based on pressure, fixture demand, and friction loss. Larger homes or longer runs may require upsizing to maintain proper flow.

Drain and Sewer Materials

• Cast iron
• ABS
• SDR 35 for exterior sewer

Drain systems are sized according to fixture units and venting requirements. Slab homes may require trenching if underground drains are being replaced.

Gas Pipe Materials

• Black iron pipe
• CSST systems
• Polyethylene for underground lines

Gas systems are sized based on total BTU load and total pipe length to prevent pressure drop.

Step 3: Access Openings

Walls and ceilings are opened in controlled areas to route new piping. The goal is to minimize disruption while allowing proper installation.

Crawl space homes allow underfloor routing. Slab homes may require attic routing for water lines.

Step 4: Installation of New Piping

Old pipes are abandoned in place once disconnected. New piping is installed, supported, and strapped according to code.

• Install new main lines
• Run branch lines to fixtures
• Connect valves and stub outs
• Secure and support all piping

For drain repipes, proper slope and vent connections are critical. For gas repipes, correct pipe diameter and appliance connections are verified.

Step 5: Pressure Testing and Inspection

Water and gas lines are pressure tested before walls are closed. This confirms there are no leaks and that the system holds pressure properly.

If permits are required, inspections are completed before final patching.

Step 6: Patching and Restoration

After testing and approval, access openings are patched. Homes are left clean and ready for paint.

How Long Does Repiping Take?

Most full water repipes are completed in 1 to 2 days depending on home size and layout. Drain and gas repipes vary depending on accessibility and scope.

Why Proper Design Matters

Repiping is not just replacing pipe. It requires correct sizing, proper routing, accurate load calculations, and professional installation to ensure long term performance.

For a full evaluation of your home’s plumbing system, contact SoCal Repipes.