What is the minimum slope percentage necessary for a site to effectively shed water?

The correct answer is that a minimum slope percentage of 2% is generally recognized as effective for water shedding on a site. This slope is sufficient to ensure that gravity can assist in directing water away from structures and prevent pooling or water damage. A 2% slope means that for every 100 units of horizontal distance, the elevation changes by 2 units, which is enough to promote drainage without being so steep that it could cause erosion or runoff issues.

While steeper slopes like 3% or 5% can also promote effective drainage, they may introduce other challenges such as increased erosion potential or instability, making a 2% slope a practical and balanced solution for most landscaping and site design needs. It is often used as a guideline in various planning and civil engineering contexts to design effective drainage systems.

Other slope percentages, such as 1%, may be insufficient for ensuring that water effectively drains away, which could lead to water-related problems on the site.