To calculate the load factor for a DWV system, what information should be used?

To calculate the load factor for a Drainage, Waste, and Vent (DWV) system, it is essential to refer to the applicable local code. Local plumbing codes provide guidelines on how various factors should be considered in the sizing, installation, and expectation of the DWV systems, including load factors. These codes are established to ensure that the systems will function properly and safely, taking into account not only the types of fixtures that may be installed but also the overall expected flow of waste and water.

Using the local code provides a standardized approach that incorporates factors such as fixture units, drainage capacities, and other criteria that have been determined based on past experience and engineering practices. This means that relying solely on manufacturer specifications, average pipe lengths, or types of waste materials might not offer a complete or adequate evaluation of the load factor needed for proper system design. Adhering to the local code ensures that installations are compliant with legal standards and best practices in plumbing.