Arizona Plumbing Practice Exam

What is the minimum slope of a horizontal drain pipe that is less than 3 inches?

1. 1/8 inch per foot

2. 1/4 inch per foot

3. 1/2 inch per foot

4. 3/4 inch per foot

The correct answer is: 1/4 inch per foot

The minimum slope for a horizontal drain pipe that is less than 3 inches in diameter is typically set at 1/4 inch per foot. This slope ensures proper drainage and prevents the accumulation of waste material and potential clogs within the pipe. A slope that is too shallow, such as 1/8 inch per foot, may not provide enough force for wastewater to flow effectively, leading to potential blockages. On the other hand, a slope that is too steep, like 1/2 inch per foot, could cause the liquid to flow too quickly, leaving solids behind and also risking erosion of the pipe's interior. Therefore, 1/4 inch per foot strikes an optimal balance for effective drainage while minimizing the risk of clogs and sediment buildup.