Sump die ancient books, "Xi'an City Wall · Construction articles" had talked about the sump: Xi'an city wall of the sump drain construction. Forty-six years of Qing Emperor Qianlong built chaired Bi Yuan governor of Shaanxi. Chutes for the masonry structure, to be affixed to the walls of the inner wall of the city went up to the top of the upright the city group. On which a stone spit faucets, slot width 0.65 m, 0.70 m deep, two walls of brick, each 0.60 m thick. Lower Town dripping stone, and ditches connected. Rainwater can tap into the spit, trough from top-down city, to the dripping stone, then scattered into the sewer flow to. The purpose of the wall is prevented by rain soaked the walls and Ruined, plays an important role for the protection of the walls! It seems drainage problems since ancient times and people living intertwined. Into modern life, the drainage is important, timely and appropriate drainage may be able to avoid a disaster. Drainage channels that mold is especially important. I plant gutters styles ranging from mold, it can be said variety, you can think of, we have U-shaped, butterfly, trapezoidal and more! Sump mold plastic mold, plastic in fact, it is a synthetic resin, natural resin in shape with pine resin similar chemically synthetic means, and is called plastic.