Rainwater recovery device for building construction

The utility model relates to a rainwater recovery device for building construction, which comprises a drainage pipeline, an expansion slot is arranged on the periphery of the drainage pipeline, one side of the expansion slot is fixedly connected with the drainage pipeline, the other side of the expansion slot is arranged on a wall body, a U-shaped pipeline is arranged in the expansion slot, and the U-shaped pipeline comprises a water collecting tank, a water inlet channel, a sludge sedimentation channel and a water outlet channel. The water collecting tank is arranged in an arc shape, a water inlet channel is arranged at the bottommost end of the arc shape and communicated with the water collecting tank, the bottom of the water inlet channel is communicated with a sludge sedimentation channel, the other side of the sludge sedimentation channel is connected with a water outlet channel through a vertically upward pipeline, and the water outlet channel is arranged above the edge of the drainage pipeline. A sewag