Basement Flooding in Oshawa: Durham Region’s Sewers, the City’s Storm Drains and Oshawa Creek

Which pipe, which government

Sewer backup arrives at the floor drain, a basement toilet or the laundry standpipe, during or just after heavy rain, and smells like sewage: that is the sanitary system, which Durham Region owns beyond your property line. Groundwater arrives clear at the wall-floor joint and through cracks after long rains and in the thaw: that is your weeping tile and drainage. Water coming down the driveway, over a window well or up from Oshawa Creek is storm water: the City of Oshawa owns the storm sewers and catch basins, and the Central Lake Ontario Conservation Authority regulates the creek valleys.

Photograph where the water first appeared and when. Durham Region takes reports on the sanitary system, the City on storm drainage, and a plumber handles what is yours.

What the fixes do, and who has helped pay

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 from the sewer and extending them away from the foundation is the cheapest fix and often the most effective.

Durham Region and the City of Oshawa have each offered protective plumbing programs at different times, covering backwater valves, sump pumps and downspout disconnection at eligible homes, with conditions that the work be done by a licensed plumber under a City permit. The programs change; check both current pages before signing a quote.

• Durham Region and City program pages checked for eligibility
• Licensed plumber and City of Oshawa plumbing permit number
• Camera inspection recording and locate
• Sump pump tested and battery backup quoted
• Downspouts disconnected and extended

Who owns which pipe

In Oshawa the owner is responsible for the sanitary lateral on private property up to the property line, and Durham Region for the sanitary sewer beyond it. The City owns the storm sewers, catch basins and creek works. 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 and the creeks

Houses near the old plants and downtown from the 1910s to 1950s often have clay weeping tile that silted up decades ago and block foundations that groundwater passes through; waterproofing there is excavation, a membrane and new drainage. Properties along Oshawa Creek and Harmony Creek face spring flooding from the creek itself, which no sump pump fixes; the Central Lake Ontario Conservation Authority publishes flood-plain mapping and regulates work in the valleys. North Oshawa’s post-2000 subdivisions have builder-installed sump pumps that may never have run; lift the float and test it.