noun
tap water; Adam's ale
Jocular term for tap water, likening it to beer from an iron pipe. Used humorously, often when someone asks for water instead of alcohol.
「何飲む？」「俺は鉄管ビールでいいよ。」
"What'll you have?" "I'm fine with tap water."
居酒屋で鉄管ビールを頼むと、笑いが起きることがある。
Ordering 'iron-pipe beer' at an izakaya can sometimes get a laugh.