In 2008 I built an outdoor kitchen out of cinder blocks. I even made the top surface out of poured concrete and then tiled the top and did stucco on the sides. I also did a 6 inch backsplash. What I failed to do was taper the top for water runoff. Because of this water will pool on the surface when it rains. I plan to retile the top and backsplash but before this I need to know how much of a pitch is required. What also complicates matters is that the top surface is designed in the shape of an "L". If I pitch from one inside corner to the other edge would require a 2" difference in slope from that inside edge to the outside edge if I use a 1/4" per foot slope. I have attached a picture of the structure.