排水井是为城市地下基础设施的供电、给水、排水、排污、通讯、有线电视、煤气管、路灯线路等维修，安装方便而设置的。一般设在管道交汇处、转弯处、管径或坡度改变处、以及直线管段上每隔一定距离处，是便于定期检查附属构筑物。
Drainage wells are set up for the maintenance of power supply, water supply, drainage, sewage discharge, communication, cable TV, gas pipe and street lamp lines of urban underground infrastructure. Usually located at the intersection of pipelines, turning points, changes in pipe diameter or gradient, as well as at a certain distance on the straight line section, it is convenient to inspect the auxiliary structures regularly.
它的主要作用是收集道路路面 雨水而设置的,有些老城是雨水污水合流，那也兼收污水，不过现在市政新建基本为雨污水分流，合流几乎没有，它将雨水收集后，排到道路下面的雨水管主要表现是那种雨水井箅子，又分为平箅式和立箅式两种，一般在市政道路上大约30米设置一道。
Its main function is to collect road surface rainwater and set up, some old cities are rainwater and sewage confluence, which also collects sewage, but now the municipal newly built basically for rainwater and sewage diversion, confluence almost no, it will collect rainwater, drained to the road below the rainwater pipe is mainly manifested in the kind of rainwater wells, and divided into flat-type. And vertical grate type two, generally in the municipal road about 30 meters set up together.