 The Uniform Plumbing Code (UPC) and the Uniform Mechanical Code (UMC) are both written by the International Association of Plumbing and Mechanical Officials, also known as IAPMO, an organization that was established by code officials.On May 17, 1926, the International Association of Plumbing and Mechanical Officials, or IAPMO, began with a mandate “to advance the latest and most improved methods of sanitation; to promote the welfare of and harmony between the owner, the builder, and the craftsman; to accomplish a uniformity in the application of the provisions of the ordinances; and to promulgate the mutual benefit of the members.