Basement Flooding in St. Catharines: Combined Sewers Under the Old City and the Pipes Two Governments Own

Work out which kind of flooding you have

Sewer backup arrives at the floor drain, a basement toilet or the laundry standpipe, during or just after heavy rain, and smells like sewage; the old core on combined sewers is most exposed. Groundwater arrives clear at the wall-floor joint and through cracks after long rains and in the thaw, common in the post-war bungalows across the north end where clay weeping tile has silted up. Creek flooding along Twelve Mile Creek and the ravines is a different scale, regulated by the Niagara Peninsula Conservation Authority, and no sump pump answers it.

Photograph where the water first appeared and when. The season, the smell and the location tell you which problem you have.

What the fixes do, and what the City has offered

A backwater valve is a one-way flap on the sanitary lateral that closes when the sewer surcharges so sewage cannot flow back into the house; while it is closed nothing in the house drains, which is why plumbers say not to run water during a storm. A sump pump with a pit collects groundwater from the foundation drain and pumps it outside; a battery backup keeps it running through the outages that come with the storms. Disconnecting downspouts and the foundation drain from the combined sewer, where they are connected, takes clean water out of an overloaded system, and the City has pushed downspout disconnection for that reason.

The City of St. Catharines has offered subsidy programs for backwater valves and related protective plumbing at eligible homes, with conditions that the work be done by a licensed plumber under a City permit. The programs change; read the City’s current page before signing a quote.

• City’s current subsidy program checked for eligibility
• Licensed plumber and City plumbing permit number
• Camera inspection recording and locate
• Sump pump tested and battery backup quoted
• Downspouts disconnected and extended

Who owns which pipe

In St. Catharines the owner is responsible for the sanitary lateral on private property up to the property line, and the City for the local sanitary and storm sewers beyond it; Niagara Region owns the trunk sewers and the treatment plants and the water supply behind the city system. A camera inspection with a locate tells you which side a break or blockage is on. Keep the recording; an insurer will want it for a sewer backup claim, and sewer backup and overland water are usually separate add-ons on an Ontario home policy.

Old houses in the core

Houses downtown, in Merritton and along the old canal from the 1880s to 1930s often have clay weeping tile that silted up decades ago and brick or block foundations that groundwater passes through; waterproofing there is excavation, a membrane and new drainage. Extend downspouts well away from the foundation and correct grading before spending on anything underground. Port Dalhousie properties on the lake face Lake Ontario storms and shoreline erosion as well.