What is the pipe size for a branch serving two lavatories that ends at the urinal?

For a branch serving two lavatories that ends at a urinal, the appropriate pipe size is critical for ensuring proper flow and drainage. The choice of a 1-inch pipe size aligns with typical plumbing standards for such applications.

In residential and commercial plumbing systems, a 1-inch diameter pipe is commonly used to effectively handle the combined drainage from multiple fixtures, such as the two lavatories. This size allows for adequate flow capacity, reducing the risk of clogs and ensuring that wastewater moves efficiently through the system.

Larger pipe sizes like 1 1/2 inches may be more suitable for horizontal runs or for main stacks, but for a branch line serving multiple closely situated fixtures, 1 inch is often sufficient and ensures that the plumbing design remains efficient without being unnecessarily oversized.

Smaller pipe sizes such as 1/2 inch or 3/4 inch would not provide the required capacity for two lavatories and a urinal. These homes or commercial plumbing fixtures typically need a larger diameter to accommodate the simultaneous potential flow from both lavatories, particularly if both are used at the same time or if there are any fixtures downstream. Therefore, the selected 1-inch size is both practical and within the guidelines for effective plumbing system design for