What is the recommended slope for 3-inch and smaller pipes to achieve a velocity of 2 fps?

The recommended slope for 3-inch and smaller pipes to achieve a velocity of 2 feet per second (fps) is generally accepted to be 1/4 inch per foot. This slope is specifically designed to ensure proper drainage and prevent issues like stagnation or backflow in plumbing systems.

When water flows through pipes, the velocity is influenced by the slope of the pipes. A steeper slope can lead to excessive flow rates, while too gentle a slope can cause the water to flow slower than desired. The 1/4 inch per foot slope strikes an ideal balance, as it provides sufficient gravitational pull to maintain the necessary velocity without causing turbulence or erosion within the piping system.

In plumbing design, achieving the correct slope is crucial for maintaining drainage efficiency and should align with the standards recommended by professional plumbing codes.