... cleaning 3.Withstanding wearing 4.Quiet operation Detailed description of Sewage check valvesDuckbill Valve is our special product,and it is ... used for draining sewage.In such foreign countries as Spain or America,it is ... ,seasands,reservoirs,and so on in order to dispose the sewage or to dredge the floods .Indeed ,it is environmentally-friendly ... T13323219Sewage Check ...