What is the water main demand factor typically used for a family residence?

For a family residence, the water main demand factor is typically set at 0.5. This figure is derived from guidelines established in plumbing codes and is based on the understanding that not all fixtures will be in use simultaneously. The demand factor accounts for peak water usage rates, acknowledging that various household fixtures, such as faucets, showers, and washing machines, will not all be drawing water at the same time.

Using a demand factor of 0.5 allows for a more efficient sizing of the water main, ensuring that the plumbing system can handle peak demands without being oversized, which could lead to unnecessary costs and complexity in the plumbing design. This balanced approach increases efficiency and practicality in residential plumbing systems.