Apr. 15, 2025
PEX pipe has become a popular choice for plumbing systems due to its flexibility, durability, and cost-effectiveness. However, many homeowners and DIY enthusiasts ask: Can I bury PEX pipe underground? The short answer is yes—but proper installation is critical to ensure longevity and compliance with local building codes. In this guide, we’ll explore the best practices for burying PEX pipe, address common concerns, and share tips to maximize its performance.
Why Bury PEX Pipe? Key Benefits
PEX is widely used for underground applications like water supply lines, radiant heating systems, and irrigation. Here’s why it’s a top choice:
Corrosion Resistance: Unlike metal pipes, PEX won’t rust or corrode, even in moist soil.
Freeze Resistance: PEX can expand slightly during freezing, reducing the risk of bursting.
Flexibility: Its bendable nature minimizes the need for fittings, lowering leak risks.
Long Lifespan: Properly installed PEX can last 50+ years underground.
How to Bury PEX Pipe: Step-by-Step Guidelines
Follow these steps to ensure a safe and code-compliant installation:
1. Check Local Building Codes
Before digging, consult local regulations. Requirements for burial depth, insulation, and pipe protection vary by region. For example:
Cold climates: Pipes may need deeper burial (below the frost line).
Warm climates: 12–18 inches of cover is often sufficient.
2. Choose the Right PEX Type
Not all PEX is identical. Opt for:
PEX-A: Most flexible, ideal for tight spaces.
PEX-B: More rigid and affordable.
UV-resistant PEX: Required if the pipe will be exposed to sunlight before burial.
3. Protect the Pipe
While PEX is durable, add these safeguards:
Sleeving: Run the pipe through a PVC conduit in areas with sharp rocks or heavy traffic.
Trench Lining: Use sand or smooth gravel to cushion the pipe and prevent abrasion.
Insulation: Wrap pipes in foam insulation if burying above the frost line.
4. Bury at the Correct Depth
Water Supply Lines: 12–24 inches deep (adjust for frost line).
Irrigation Systems: 6–12 inches deep.
Avoid burying PEX in areas prone to heavy machinery or digging.
5. Pressure Test Before Backfilling
Test the system at 1.5x normal pressure for 30 minutes to check for leaks. Repair any issues before covering the pipe.
Common Questions About Burying PEX
Q: Will PEX crack if the ground freezes?
A: While PEX is freeze-resistant, it’s not freeze-proof. Burying below the frost line or insulating the pipe minimizes risks.
Q: Can rodents chew through buried PEX?
A: Rodent damage is rare but possible. Use protective conduit in high-risk areas.
Q: How long does buried PEX last?
A: With proper installation, PEX can last 50+ years. Avoid direct burial near chemicals or gasoline-contaminated soil.
Q: Do I need a permit to bury PEX?
A: Permits are often required for water line installations. Check with your local building department.
PEX vs. Alternatives: Which Is Better for Burial?
Copper: Durable but prone to corrosion and costly.
PVC: Affordable but brittle in cold weather.
HDPE: Great for deep burial but harder to install.
PEX strikes a balance between affordability, flexibility, and resilience, making it ideal for most residential projects.
Final Tips for Success
Mark the pipe’s location with caution tape to avoid accidental damage during future digging.
Avoid kinking the pipe during installation—use gentle bends.
Partner with a licensed plumber for complex projects or code-sensitive work.
Conclusion
Burying PEX pipe is a practical solution for underground plumbing, provided you follow local codes and installation best practices. By choosing the right materials, protecting the pipe, and testing thoroughly, you’ll ensure a reliable system for decades. Always consult a professional if you’re unsure about any step in the process.
For more plumbing tips, check out our guides on [PEX vs. Copper Pipes] or [How to Prevent Frozen Pipes]. Have questions? Share them in the comments below!
