What is the allowable minimum slope for drainage piping in the UPC?

The allowable minimum slope for drainage piping in the Uniform Plumbing Code (UPC) is based on the size of the pipe. For pipes that are 2 inches in diameter or smaller, a slope of 1/4 inch per foot is required. This steeper slope helps to ensure that wastewater flows efficiently and reduces the likelihood of blockages. For larger pipes, specifically those greater than 2 inches, a minimum slope of 1/8 inch per foot is sufficient. This ensures that the flow remains effective while managing the velocity of water in larger pipes to prevent excessive turbulence or erosion.

Establishing a minimum slope is crucial in plumbing design as it directly impacts the performance of the drainage system. A slope that is too shallow could lead to slow drainage and potential clogs, while excessive slope might cause issues with the drainage system, such as loss of solids in the flow due to high velocity.

In this context, the other options either do not conform to the specified requirements in the UPC or suggest an inappropriate slope for certain pipe sizes, which does not effectively manage drainage needs.