Geothermal Plastic Piping Systems Certification
February 22, 2025
If you are looking to certify your geothermal plastic piping system, materials or fittings, NSF is your best option! We are the plastic industry’s leading testing and certification organization, with proven experience certifying various types of plastic pipes.

To help ensure high quality for different kinds of geothermal pipe and fittings systems, NSF published an American National Standard series. Certification to NSF/ANSI 358 satisfies requirements of the mechanical codes UMC and IMC.
- NSF/ANSI 358-1: Polyethylene Pipe and Fittings for Water-Based Ground-Source “Geothermal” Heat Pump Systems
- NSF/ANSI 358-2: Polypropylene Pipe and Fittings for Water-Based Ground-Source “Geothermal” Heat Pump Systems
- NSF/ANSI 358-3: Cross-linked Polyethylene (PEX) Pipe and Fittings for Water-Based Ground-Source “Geothermal” Heat Pump Systems
- NSF/ANSI 358-4: Polyethylene of Raised Temperature (PE-RT) Pipe and Fittings for Water-Based Ground-Source “Geothermal” Heat Pump Systems.
Testing Requirements
To be eligible for NSF/ANSI 358 certification, your geothermal plastic piping product must meet the following criteria:
- Compliance with the applicable ASTM or CSA standards (ASTM F876, F2389, F2623, D3035, CSA B137.1, etc.)
- Long-term strength test
- Chemical resistance test
- Fittings and U-bends evaluation.
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