下水管道，排水管线
the system of pipes, openings in the ground, or other devices that are used for carrying away waste matter and water
There was an unpleasant smell coming from the drains. 下水道里发出一种难闻的气味。
We need someone to come and unblock the drains.
Blocked drains can cause flooding.
Water had risen up through the drains in the floor.
The idea is that water soaks into the ground rather than flowing directly into stormwater drains.
They're clearing the clogged drains.
See also: drain noun (PIPE)