Massachusetts Plumbers Journeyman Practice Exam

What slope should storm or sanitary drains be installed at to produce a computed velocity of discharge not less than two feet per second?

1. Flat slope

2. 1/4 inch per foot

3. 1/8 inch per foot

4. Steep slope

The correct answer is: 1/4 inch per foot

The correct choice advocates for a slope of 1/4 inch per foot for storm or sanitary drains. This specific slope is optimal because it provides sufficient gravitational force to ensure that wastewater moves swiftly through the system, thereby achieving a velocity of discharge of at least two feet per second. This velocity is crucial for preventing sediment buildup within the pipes, which can lead to blockages and other plumbing issues. When drains are installed at a flatter slope, they may not generate enough force to facilitate proper drainage, resulting in stagnation. Conversely, a steeper slope could lead to excessive velocity, which can cause erosion or damage to the drainage system. Therefore, a 1/4 inch per foot slope strikes the right balance for effective drainage while maintaining the integrity of the plumbing infrastructure.