Massachusetts Plumbers Journeyman Practice Exam

What pitch should be used when installing horizontal drainage piping that is (3) three inches in diameter or smaller?

1. 1/8 inch per foot

2. 1/4 inch per foot

3. 1/2 inch per foot

4. 1 inch per foot

The correct answer is: 1/8 inch per foot

For horizontal drainage piping that is three inches in diameter or smaller, a pitch of 1/4 inch per foot is the correct standard. The purpose of this specific pitch is to ensure adequate drainage flow, minimizing the risk of clogs and promoting the efficient movement of wastewater through the system. Using a 1/4 inch per foot slope allows for sufficient gravity assistance in moving waste material, while also preventing the risk of pooling water that could occur with a flatter slope. A pitch that is too shallow might lead to drainage issues, while a steeper pitch could result in the waste moving too quickly, potentially causing solids to settle in the pipe. Thus, while it is important to have a proper slope for effective drainage, it's widely accepted within plumbing codes and standards that the appropriate pitch for pipes of this size is 1/4 inch per foot.