下水
げすい · gesui · JLPT N2 · noun
drain
🚰 下水 = under + water: the water that runs underground, down through drains
下 means under or down, 水 means water. Sewage, drainage and gutters all carry water downward and away, out of sight below the street.
下 — horizontal line 一 + mark below
下 is an indicative character: a long horizontal line represents a reference level, and a shorter stroke placed beneath it points to the area below. The original meaning 'below, down' comes directly from this spatial diagram, and it later extended to verbs like 'descend' and 'lower'.
水 — pictograph of flowing water
水 is a pictograph depicting a stream of flowing water, with the central line representing the main current and the side strokes showing splashing droplets or ripples. In oracle bone script it was drawn even more clearly as a wavy vertical line with branches. It retains its original meaning of 'water' and also serves as a radical, often appearing in the compressed form 氵.