How are plumbing pipes typically graded for drainage?

Plumbing pipes used for drainage are primarily graded based on their slope towards the discharge point. This is critical because proper drainage relies on gravity to move wastewater away from fixtures and towards the sewer or septic system. The slope, often expressed as a ratio (e.g., 1/4 inch per foot), ensures that the wastewater flows efficiently, reducing the risk of clogs and backups.

While diameter size is important for determining the volume of water a pipe can carry, it does not dictate how effectively the drainage system operates. Color coding may assist in identifying pipe types or purposes but does not affect the grading for drainage. Material composition is relevant for factors like durability and resistance to corrosion, but it does not influence the grading of pipes for drainage purposes, which is fundamentally concerned with how pipes are installed to promote proper flow.