Marketing InformationSioux Chief 869 Series backwater valve shall be installed where necessary in drainage systems. Backwater valve shall be installed in horizontal drainage lines to reduce or prevent damage to dwelling from sewage backup. Backwater valve shall have a stepped design with a one-way flapper to prevent back flow of sewage/drainage. Flapper shall have an o-ring seal and allow unrestricted, unidirectional flow while reducing the straining of effluent. Designed in accordance with ASME A112.14.1-2003.