PP composite HDPE drainage board is manufactured with an exclusive co-extrusion process to get a dimpled membrane made of high density polyethylene (HDPE) drainage core, then heat-bonded polypropylene (PP) non-woven geotextile. The HDPE drainage core with a specially designed dimple pattern provides high compressive strength and drainage capacity, thus preventing the build-up of hydrostatic pressure against the waterproofing layer. It also acts as a highly effective protection layer for the waterproofing material during backfill operations. The second layer geotextile retains soil or sand particles as well as freshly placed concrete or grout, allowing filtered water to pass into the drainage core. This is a multifunctional material that can form channels for water and gas.