A. Sump receivers, sometimes called drain receivers, should be used with roof drains to compensate for deck opening irregularities and provide proper support for the drain. The sump receiver is a flat steel plate with a depressed center opening into which the roof drain body flange fits, the sump receiver is supported by the lip of the opening in the deck. In addition to easing the deck opening tolerance requirements, the sump receiver distributes the weight of the drain over a larger surface of the deck.