Understanding and Assessing Impacts
Backwater valves are, effectively, a one-way gate that is placed inside the sanitary sewer lateral of a home. They allow for wastewater to flow out from the home into the sewer system, but prevent sewage from flowing into the home via the sewers during a flooding event. Research has consistently shown that these are an effective tool for the prevention residential flooding, which is a phenomenon that now consistently causes more than $2 billion in damages annually in Canada. However, a backflow valves does require maintenance in order to work properly. An analysis of Ottawa’s 2009 flood indicated that the most common point of failure was the valve cover, which was often not screwed into place adequately, causing eh system to fail. Other notable possible causes of backwater valve failure is a degradation of the O-rings in the system, preventing a complete seal, or the collection of debris under the gate itself, which can cause the gate the stick in the open position and thus rendering in unable to stop sewer backflow from entering a home. As the climate continues to change, it is likely that extreme rainfall events will become more common, necessitating a greater reliance on preventative devices like backwater flow valves.