While product specifications and regulations on plumbing products' use and installation have been around for centuries, the fathers of modern plumbing codes are really Herbert C. Hoover and Roy B. Hunter.
Hoover, while still Secretary of Commerce, developed what is now called the "Hoover Code," a rough approximation of today's plumbing codes.
In the 1940s, Dr. Roy Hunter of the National Bureau of Standards developed and published BMS 66, a methodology for determining necessary pipe sizing by estimating maximum demand on the delivery and drainage systems. This was developed because one of the major code concerns was then, and is now, pipe sizing -- both for supply and drainage piping in a building. While "tweaked" over the years, Hunter's basic work is still used as the basis for pipe sizing in a plumbing system.
During the developmental years of plumbing codes, local enforcement officials determined they would be better off using a "model code" rather than writing their own for every jurisdiction in the country.
Organizations were formed to write model codes, which were largely "regionalized":
- International Association of Plumbing and Mechanical Officials (IAPMO) - developed the Uniform Plumbing Code (UPC) - used mostly in the Western United States;
- Building Officials and Code Administrators International (BOCA) - developed the National Plumbing Code (NPC) and National Building Code (NBC) - used primarily in the Northeastern United States;
- Southern Building Code Congress International (SBCCI) - developed the Standard Plumbing Code (SPC) and the Standard Building Code (SBC) - used primarily in the Southeastern United States;
- International Conference of Building Officials (ICBO) - developed the Uniform Mechanical Code (UMC, originally a joint project with IAPMO) and the Uniform Building Code (UBC), which served as a complement to IAPMO's UPC in the Western United States.
These organizations also developed educational and professional certification programs for their constituencies.
While not the "granddaddy" of codes, the A40 Standard (which is really a plumbing code) rates high on the list of important documents. The original A40 document of 1955 was the amalgamation of Hoover's and Hunter's work and effectively set both the form and content of today's model codes.
Failed efforts to update the 1955 A40 standard during the 1960's caused the development of the National Standard Plumbing Code (NSPC). Its format and language grew directly from the never-ratified drafts of A40 updates. The A40 concept of a true, nationally recognized plumbing code was revitalized in 1972 when a new committee was formed to write a new A40 code. The end result of the effort established in 1972 was the publication of a new A40 Standard in 1993.
It is important to note that the A40 document is referred to, usually, as a code or standard. A40 is an American National Standard. The American National Standards Institute (ANSI) does not recognize codes per se. The A40's language and form, however, cover plumbing products as do all the other regulatory documents known as installation codes.