ASSE 1099 – Mechanical Performance Testing of Pressurised Water Storage Tanks

What is ASSE 1099?

ASSE 1099, titled "Performance Requirements for Pressurised Water Storage Tanks", is an American National Standard developed jointly by ASSE International and the Water Systems Council (WSC).

This standard establishes minimum performance and construction requirements for pressurised water storage tanks used in water well systems, particularly in residential applications. These tanks are essential for storing groundwater under pressure, ensuring a reliable supply of cold water to homes and buildings. The standard ensures tanks can:

• Withstand high internal pressure without leaking or rupturing.
• Maintain a sealed, sanitary environment to prevent contamination.

Key specifications

• Factory pre-charge pressure: Maximum of 40 psig (276 kPa)
• Working pressure range: Between 75–150 psig (517–1034 kPa)
• Tank volume: Up to 120 gallons (454 litres)
• Temperature tolerance: Up to 120°F (49°C) in ambient air.

Certification and compliance

ASSE 1099 was adopted into the Uniform Plumbing Code (UPC) in 2024 and is scheduled for inclusion in the International Plumbing Code (IPC) in 2027. The State of California will adopt the updated UPC beginning January 1, 2026.

To be certified, products must:

• Be tested by accredited laboratories (ILAC-MRA signatories).
• Undergo audits for manufacturing consistency.
• Be listed by the Water Systems Council.
• Be retested periodically to maintain certification.

Why work with NSF?

NSF is fully accredited to test and certify products to ASSE 1099, and our certification is recognised and accepted by U.S. plumbing codes nationwide.

All testing to ASSE 1009 is performed in NSF’s own laboratories, ensuring accurate results, consistent quality, and faster turnaround times.

If you’re already certifying your pressurised water storage tanks under NSF/ANSI/CAN 61 with NSF, you can combine audits with ASSE 1099 certification for time and cost savings.