雨水积聚在排水道里。
在这些城市，雨水和生活污水由相同的排水系统排放，意味着当下水道水量过大，未经处理的污水会直接涌向河流和溪流。
These cities collect stormwater and sewage in the same pipes, which means that when sewers are overwhelmed, raw sewage floods directly into rivers and streams.
雨水排水也会通过水管或管道进入水道，这都被认为是非点源污染。
Storm drainage, even though the water may enter watercourses by way of pipes or channels, is considered nonpoint source pollution.
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