Uniform Plumbing Code (IAPMO/ANSI UPC 1-2021)

If extraterrestrials landed on Earth, across homes, they would find furniture designed for similar purposes, lights in typical placements, an affinity for screens, and, of course, small rooms of porcelain and faucets. Plumbing systems are crucial; therefore, so is the Uniform Plumbing Code, or IAPMO/ANSI UPC 1-2021.

Plumbing systems have advanced over time, but they have functioned since antiquity. In fact, the Cloaca Maxima, the ancient Roman sewer system constructed in the 6^th Century BC, is still in use today. In the U.S., the first waterworks emerged in Philadelphia in 1802, and other major cities throughout the nation created similar water and sewage systems during the decades that followed.

Centuries of development in the New World and millennia of improvements across the globe have advanced plumbing systems, but they have also introduced numerous avenues for differentiation. The need for harmonization within the plumbing industry, not only for comfort in the home but also public health and sanitation, gives purpose to the Uniform Plumbing Code.

What is the Uniform Plumbing Code?

IAPMO/ANSI UPC 1-2021: Uniform Plumbing Code provides minimum requirements and standards to protect public health, safety, and welfare. Its provisions are applicable to the erection, installation, alteration, repair, relocation, replacement, use, or maintenance of plumbing systems.

The advantages of a Uniform Plumbing Code are recognized across the industry, which can undergo disorder when widely divergent plumbing practices and codes are utilized. The need for harmonization throughout the plumbing industry culminated in the initial adoption of the Uniform Plumbing Code by IAPMO in 1945.

IAPMO/ANSI UPC 1-2021 is the twenty-ninth edition of the Uniform Plumbing Code and the seventh edition to be developed under the ANSI consensus process. The UPC updates every three years.

Chapters of IAPMO/ANSI UPC 1-2021

The Uniform Plumbing Code’s format keeps the user in mind. Each chapter of IAPMO/ANSI UPC 1-2021 is dedicated to a specific subject matter. However, several chapters focus on broader components pertinent to the entire document—Chapter 1 details administration, Chapter 2 offers definitions, Chapter 3 is dedicated to general requirements that are applicable to every chapter, and Chapter 17 features a list of referenced standards.

Other subject matters are divided throughout IAPMO/ANSI UPC 1-2021 as:

Chapter 4, Plumbing Fixtures and Fixture Fittings
Chapter 5, Water Heaters
Chapter 6, Water Supply and Distribution
Chapter 7, Sanitary Drainage
Chapter 8, Indirect Wastes
Chapter 9, Vents
Chapter 10, Traps and Interceptors
Chapter 11, Storm Drainage
Chapter 12, Fuel Gas Piping
Chapter 13, Health Care Facilities and Medical Gas and Medical Vacuum Systems
Chapter 14, Firestop Protection
Chapter 15, Alternate Water Sources for Nonpotable Applications
Chapter 16, Nonpotable Rainwater Catchment Systems

Each chapter delves into its respective topic and outlines information pertinent to meeting the code for each subject in pursuit of assuring public health.

For example, Chapter 4 regulates the minimum number of plumbing fixtures of a specific type and quality; Chapter 5 deals with the design, approval, installation, and safety of fuel burning and other water heaters with combustion air requirements for ventilation and dilution of flue gases; Chapter 6 covers the design, materials, and installation of water supply and distribution systems, including residential fire sprinklers; and Chapter 7 details the design and installation of sanitary drainage systems so they work as intended.

Furthermore, IAPMO/ANSI UPC 1-2021 contains numerous appendices. The provisions found in these sections supplement the requirements of the Uniform Plumbing Code, but are not to be considered part of the code, unless formally adopted as such. The appendices in the UPC include:

Appendix A, Recommended Rules for Sizing the Water Supply System
Appendix B, Explanatory Notes on Combination Waste and Vent Systems
Appendix C, Alternate Plumbing Systems
Appendix D, Sizing Storm Water Drainage Systems
Appendix E, Manufactured/Mobile Home Parks and Recreational Vehicle parks
Appendix F, Firefighter Breathing Air Replenishment Systems
Appendix G, Sizing of Venting Systems
Appendix H, Private Sewage Disposal Systems
Appendix I, Installation Standards
Appendix J, Combination of Indoor and Outdoor Combustion and Ventilation Opening Design
Appendix K, Potable Rainwater Catchment Systems
Appendix L, Sustainable Practices
Appendix M, Peak Water Demand Calculator
Appendix N, Impact of Water Temperature on the Potential for Scalding and Legionella Growth (this is a new appendix added to the 2021 edition of the code)

Which states adopt the Uniform Plumbing Code?

Past editions of the Uniform Plumbing Code have been adopted by several states, including Alaska, Montana, Nevada, South Dakota, New Mexico, Hawaii, and Washington. Iowa has adopted the 2021 code. In addition, the California Plumbing Code, North Dakota Plumbing Code, and Minnesota Plumbing Code are based on the 2018 Uniform Plumbing Code. The Idaho State Plumbing Code and the Maine State Plumbing Code are based on the 2015 UPC. The Oregon Plumbing Specialty Code is based on the 2021 UPC.