Sewage drainage system

The utility model relates to the technical field of domestic sewage collection and treatment, in particular to a sewage drainage system, which comprises a water collection tank, a drainage pipe, a drainage pipe and a drainage pipe, the first underground drainage pipe is arranged at the bottom of the water collecting tank and is communicated with the water collecting tank; the first floor drain is mounted at the top end of the first underground drainage pipe and can filter impurities in the sewage before the sewage in the water collecting tank flows into the first underground drainage pipe. The bottom of the water collecting tank is located under the ground of the courtyard, and the side wall of the water collecting tank upwards extends out of a water retaining table higher than the ground of the courtyard. According to the sewage drainage system, the water collection flow grooves are formed in the periphery of the first floor drain, so that discharged sewage can be completely collected, the sewage collection