How to Build a Retaining Wall the Right Way: Avoiding Failure Through Proper Drainage Retaining walls are essential structures in landscaping and construction, used to hold back soil on sloped terrain and create level areas. However, many retaining walls fail prematurely due to one critical mistake: poor drainage. The image clearly illustrates the difference between an incorrect retaining wall and one built the right way. The Problem with Improper Retaining Walls On the left side of the image, t