Mitigation of Basement Flooding due to Sewer Backup: Overview and Experimental Investigation of Backwater Valve Performance

Abstract

Extreme rainfall–related urban flooding and consequently, basement flooding due to sewer surcharge, has become one of the most significant drivers of disaster losses in Canada. It has been recommended that homeowners living in flood-prone regions protect their properties against basement flooding by installing backwater valves on sewer laterals and branch lines connected to plumbing fixtures. The most common causes of valve failure are identified and categorized into the following groups: (1) flow rates; (2) valve condition; (3) lateral slope; (4) lateral condition; and (5) wastewater material. A testing protocol developed through experimental design with respect to the failure-mode classifications is proposed to determine the lifecycles and maintenance intervals for different backwater valve models. The results may be used to create policies and recommend maintenance procedures to ensure an acceptable level of backwater valve function and to mitigate the occurrence of basement flooding events due to sewer surcharge.