What slope percentage is commonly used for drainage on paved surfaces such as parking lots?

The commonly used slope percentage for drainage on paved surfaces, such as parking lots, is typically around 1%. This slight incline is sufficient to facilitate water runoff, preventing water pooling and potential damage to the surface. A 1% slope equates to a 1-foot drop over a 100-foot distance, which is gentle enough to be unobtrusive while effectively directing water towards drainage systems.

In contrast, steeper slopes, such as 2%, 3%, or 5%, may be suitable for certain applications but can lead to issues such as increased erosion, difficulty for pedestrians and vehicles, and potential drainage problems if not properly matched with the design of drainage systems. Therefore, a 1% slope is a standard practice in many cases for ensuring effective water drainage while maintaining surface usability.