Sentence:  We said earlier that we normally use a curved or bent piece of pipe at the top of the <WSD>drainpipe</WSD> where it is connected to the gutter, and a fitting at the bottom end of the <WSD>drainpipe</WSD> that directs the water into a channel or a drain or gully. 
Meaning of the word marked with <WSD> tags:  A verticle pipe carrying water from the roof gutter down the side of a building; downspout.