Literally meaning to pour water from a high roof, this phrase describes someone operating from a strategically advantageous position or having an overwhelming, irresistible momentum; to look down from a height.

to pour water from a vase on a high roof; a strategically advantageous position or an irresistible force

(literary) a brick used for building; a block of tile

(literary) a brick used for building or paving

(idiom) describes a situation that is progressing smoothly and without resistance; literally "smash bamboo and overturn a water jug"