One is to decontaminate with chemicals; First pour boiling water into the pipeline, then pour caustic soda or pipeline dredging agent into the blocked pipeline, and wait for one or two hours. The chemical cleaning agent will decompose the sundries blocked in the pipeline and make the pipeline unblocked again. The other is physical dredging method; You can buy a dredge, install it according to the tutorial, and adjust the air pressure to a suitable range. Then hit the sewer entrance several times until it is clear.