What minimum slope is required per foot of a 4 inch horizontal drain pipe?

The correct choice indicates that a minimum slope of 1/8 inch per foot is required for a 4-inch horizontal drain pipe. This slope is essential for proper drainage, allowing wastewater to flow smoothly through the pipe and preventing clogs and backflow issues.

A slope of 1/8 inch per foot ensures that the wastewater maintains sufficient velocity as it moves through the pipe, aiding in the transport of solids and reducing the likelihood of sediment buildup. This standard is commonly accepted in plumbing codes and practices, as it strikes a balance between adequate drainage and the structural integrity of the piping system.

In contrast, steeper slopes, such as 1/4 inch or greater, can lead to problems where the water rushes too quickly, possibly leaving solids behind. A slope less than 1/8 inch may not provide enough gravitational pull for effective drainage. Thus, the minimum requirement of 1/8 inch is established to optimize the function of horizontal drain pipes while preventing potential plumbing issues down the line.