DRAINAGE STRUCTURE WITH BACKFLOW INHIBITING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a drainage structure with a backflow inhibiting device which enables a state of a water level at a drainage side to be indirectly grasped and prevents damage due to flood.SOLUTION: A device body 31 of a backflow inhibiting device 30 has: a ventilation pipe body section 33 which configures a ventilation passage 34 communicating with gas phase spaces Y in a downstream side pipe section 14 and a backflow prevention pit 1; a float valve body 40 arranged in the ventilation passage 34; and an engaging section 42 at an upper edge section of the ventilation pipe body section 33. The backflow inhibiting device 30 enables an operator to have visual contact with the float valve body 40 when the same is engaged with the engaging section 42 and positioned at an upper limit position.