Abstract: A normally-open backwater valve fluidly coupled between one or more discharge conduits of a building, or other location, and a sewage, or drainage, system includes a valve body having a horizontally-oriented fluid flow passageway, a flapper pivotably moveable therein and at least one spacer configured to position the flapper above the lower interior surface of the valve body in the passageway when the flapper is in an open position.