Prevent street sewer waste from backflowing into basements or low areas with the ABS 3 in. Backwater Valve. The backwater valve is lightweight and easy to install. The quick action flapper allows unrestricted uni-directional flow. Elastomeric gasket in the flapper ensures a watertight seal. Flapper can be easily removed and replaced if required. Access cap neoprene gasket provides a positive seal. Valve hub outlets fit 3 in. DWV pipe. Horizontal installation required, with arrows on top of the valve hub pointing in the direction of the flow of water. This backwater valve is a chemically resistant alternative to cast iron valves. Durable backwater valve is made of ABS. Backwater valves are used to prevent backflow in pipelines. Backwater valves are one-way valves installed in pipe systems to allow waste to flow through freely but will automatically close off if the flow reverses, in order to protect the pipe and other system components. NDS backwater valves are engineered for ease of installation, durability and performance. NDS offers a range of engineered specialty fittings and valves for residential, commercial, and industrial applications. Access specifications and project design support on the NDS website. NDS is a leader in flow management solutions and the preferred choice of professionals. Material: Acrylonitrile Butadiene Styrene (ABS).