The NPC sets out technical provisions for the design and installation of new plumbing systems. It also applies to the extension, alteration, renewal and repair of existing plumbing systems.

New information has been added to make the 2005 NPC clearer, easier to apply to existing plumbing systems and more accommodating to innovation. It explains the objectives that the Code's provisions are intended to achieve and describes the functions that a plumbing system or its components must perform to fulfill these objectives.

The NPC also has a new organizational layout that comprises three divisions: Divisions A, B and C. Division A includes the compliance options, the objectives and the functional statements. Division B contains the provisions-now referred to as "acceptable solutions" - relating to such issues as materials and equipment, piping, drainage systems, venting systems and potable and non-potable water systems. Division C contains administrative provisions.