Introduction to the S-shaped drainage system: The S-shaped drainage system is located in the patio and is closely connected to the eaves corridor. The sloped roofs on the four sides of the eaves corridor form a trend of "four waters uniting", connecting the indoor and outdoor spaces into one, pursuing the "heaven and man" the ideal of unity. Its drainage system is very special. Based on the requirements of ancient Feng Shui, it adopts an S-shaped direction, bypassing the main hall and draining water forward. The implication is to prevent money from leaking. According to Chaozhou custom, water brings wealth, so water cannot be drained directly. The height difference from the main entrance to the main hall, back hall and back seat of Xu Huima's Mansion is 1.28 meters, which means "step by step". This height difference cleverly prevents the S-shaped drainage system from being blocked for more than 940 years. The entire mansion has never been flooded due to heavy rains.