What is the maximum number of water closets that would be allowed on a 4" building drain with 1/4 inch slope?

To determine the maximum number of water closets that can be connected to a 4-inch building drain, it is essential to reference plumbing codes and standards that specify drainage capacity and fixture units for different sizes of drains.

A 4-inch building drain can typically handle a certain load based on the designed flow capacity and the type of fixtures connected to it. The plumbing code outlines that each water closet contributes a specific amount of fixture units. For a standard water closet, it is common to assign a value of 3 fixture units.

Using the commonly accepted calculations, a 4-inch building drain can typically accommodate a maximum of 54 fixture units. To translate fixture units into the number of water closets, we can divide the total fixture units allowed by the number of fixture units each water closet contributes.

In this case, when we take the maximum fixture units of 54 for a 4-inch drain and divide by 3 units per water closet, we find that up to 18 water closets could be logically supported. However, plumbing codes may permit additional considerations, such as offsetting factors for the layout and design of the plumbing system and the overall use.

Thus, the calculation leading to the conclusion of allowing up to 54 water closets on a