Abstract: Flumes for manhole inverts are described and formed of integrally molded segments which interfit with each other so as to connect inlets to an outlet of a manhole independent of the shape and size of the manhole. The flumes are made in a set and in one set the flumes are formed of a pipe segment which either is integrally connected to an open channel segment or connected thereto with suitable fasteners and with the overall length of the flume being substantially less than the distance between the inlet and an outlet of the manhole. Another set of flumes has only open channel segments which are generally substantially smaller in length than the flumes which have both a pipe and an open channel segment. The open channel segments are provided with end flanges to enable their connection to similarly shaped channel segments to form inverts.