The 2021 edition of the Uniform Plumbing Code represents the most current approaches in the plumbing field. It is the seventh edition developed under the ANSI Consensus process is designated as an American National Standards by the American National Standards Institute (ANSI). Contributions to the content of this code were made by every segment of the built industry, including such diverse interests as consumers, enforcing authorities, installers/maintainers, labor, manufacturers, research/standards/testing laboratories, special experts and users. The UPC is designed to provide consumers with safe and sanitary plumbing systems while, at the same time, allowing latitude for innovation and new technologies. Key changes to the 2021 UPC include: New Appendix N: Impact of Water Temperature on the Potential for Scalding and Legionella Growth. New provisions for backflow prevention devices, assemblies, and methods. New provision of temperature limiting devices. New guard and rail requirements for appliances on roofs and platforms. New requirements for the discharge of temperature and pressure relief valve piping. New provision on leak detection devices. Provisions for potable water pumps. New standards for drain, waste, and vent pipe and fittings. New provisions for drain waste and vent cleanouts. Circuit vent provisions have been updated and expanded. Updated to fuel gas provisions. Updated medical gas provisions including reordering of categories for ease of use.