What property of a drain is crucial for ensuring proper water flow?

The diameter and slope of a drain play a vital role in ensuring proper water flow. The diameter dictates how much water can pass through at any given time; if the diameter is too small, it can create a bottleneck, leading to slow drains or backups. The slope, or pitch, is equally important, as it affects the velocity of the water flow down the drain. A proper slope ensures that gravity effectively pulls the water and waste downhill. If the slope is too shallow, water can stagnate, leading to clogs, while a slope that is too steep can cause water to flow too quickly, potentially leaving solids behind. Together, the diameter and slope create optimal conditions for efficient drainage.