6" PVC Backwater Valve, 6 Inch Back Flow Preventer Valve, Backflow Water Valve Prevents Sewage Backflow About this item Designed for connecting 6-inch PVC drains in the drainage system, this valve prevents the backflow of water in the pipeline due to pressure reduction or other potential causes. The backwater valve is made of durable PVC for high impact strength and resistance to heat and corrosion. Our back flow preventer valve can be solvent-welded for a watertight connection. The installation is simple and efficient. Thickened rubber rings embedded in the water stop baffle guarantee a watertight seal, and the access cover is also sealed with EPDM rubber to prevent water leakage. The backflow valve, as part of the DWV system, is suitable for connecting PVC sewers and drains. Ideal for sewage disposal in household and certain industries, it prevents sewer backflow.