Performance evaluation of backwater valves to mitigate basement flooding from sewer surcharge events

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Basement flooding due to sewer back-up is the most expensive source of home insurance claims. Recent flooding events in Ontario (such as the 2005 and 2013 floods in Toronto) have resulted in hundreds of millions of dollars in property damages due to sewer backups into homeowners' basements. Occurrences of basement flooding events are influenced by numerous factors, including: an increase in magnitude and frequency of extreme precipitation events due to climate change, and aging, defective and under-designed sewer infrastructure. One lot-side technology available in the marketplace today is the backwater valve which can be installed on sewer laterals in individual homes to prevent sewer back-up through basement drains. Despite its benefits, numerous uncertainties exist regarding the performance and suitability of backwater valves. Considering this, the goal of this research is to evaluate the performance of a variety of backwater valve models subjected to sewer surcharge events. Conducted in collaboration with industry-partner the Institute for Catastrophic Loss Reduction (ICLR), this research will be conducted through full-scale laboratory testing using the Insurance Research Lab for Better Homes (IRLBH) at the University of Western Ontario. The experimental testing will characterize valve deterioration, identify causes of valve failure, evaluate the lifespan of backwater valves, and determine optimal valve models for individual home plumbing and sewer lateral configuration. Results will provide: i) guidance to improve municipal guidelines for the installation of backwater valves; ii) technical recommendations to the insurance industry to develop appropriate policy; and iii) greater information to homeowners to reduce risk of water damage due to basement flooding during sewer surcharge events.