排污水系统的英文：
sink duainager

sink into a decline
开始衰落，衰弱下去，体力衰退

Sink or fall to a lower level.
下沉或下降到更低的水平。

swallow hold (sink, sinkhold)
落水洞

Many sands will sink a ship
积沙沉船

There's a backup in the sink.
下水道堵塞。