A drainage system that is adapted to be installed between two supports. The supports may be the joists of an outdoor deck. The drainage system comprises a drainage panel and two clips. The drainage panel is comprised of a first end portion and a second end portion. A first clip is adapted to be secured to one of the supports. The first clip has a base and two flanges. The flanges extend from the base such that they converge and engage the first end portion of the drainage panel. The second clip is adapted to be secured to the other support. The second clip also has a base and two flanges. The flanges extend from the base and converge. The second end portion of the drainage panel is engaged by the flanges of the second clip.