PROBLEM TO BE SOLVED: To provide a drainage system that can prevent infiltration of water into the soil in the building area from outside the building such as a vinyl house.SOLUTION: In a drainage system 1 using an open ditch 11 placed alongside of a building 30, the open ditch 11 is formed in an adjoining land 5 which is arranged in the outside of the building 30 along the side edge of the building 30 and which is passable, and the range from the lower end of a side surface 34 of the building 30 to a groove inner side surface 11a of at least the building 30 side of the open ditch 11 is covered with a water permeation suppressive covering material 12.SELECTED DRAWING: Figure 1【課題】ビニールハウスなどの建造物の外部からの建造物領域の土壌への水の浸入を防止できる排水システムを提供することにある。【解決手段】建造物３０に併設された明渠１１を用いた排水システム１において、明渠１１は、建造物３０の外側に建造物３０の側縁に沿って配された通行可能な隣接地５に形成されており、建造物３０の側面３４の下端部から、明渠１１のすくなくとも建造物３０側の溝内側面１１ａまでを透水抑制被覆材１２で覆った。【選択図】図１
