Oshawa Plumbing Services

Frequently Asked Question

• 1. Why does my basement flood during heavy Oshawa storms even when my plumbing is fine?

  Because storm flooding usually comes from outside your plumbing. During an intense storm, water arrives faster than the ground and the City’s drainage system can absorb it, and Oshawa’s clay and glacial till soak up very little. The water builds against the foundation and the sewer system can surcharge, pushing water back toward homes through the lowest drains.

  So your interior plumbing can be in perfect condition and the basement still floods, because the water is coming from the saturated ground and the overwhelmed system around your house. The protections that address this are groundwater management, grading and a sump pump, plus a backwater valve for sewer surcharge.

• 2. What is CLOCA, and how do I know if my Oshawa property is in a floodplain?

  CLOCA is the Central Lake Ontario Conservation Authority, the agency that monitors the creeks and watersheds across Oshawa and handles flood forecasting when waterways rise after heavy rain or snowmelt. The City points residents to CLOCA for current flood status and to check whether a property sits in a regulated floodplain.

  If you are near Oshawa Creek, East Oshawa Creek, or another waterway, checking CLOCA’s flood mapping is the practical first step. Being in or near a floodplain does not mean your basement will flood, but it does mean the defences that keep water out, grading, a sump pump, and a backwater valve, matter more for your home than for one on higher ground.

• 3. Why does the older part of Oshawa flood more than newer neighborhoods?

  The City of Oshawa itself notes that roadways in newer areas were designed to carry significant storm flows, while in the older parts of the city the roads were never engineered to pass major flows. So when a big storm hits, water that would be channelled away in a newer subdivision instead ponds and backs up in older areas.

  Localized flooding is also more common where grading was changed before the City’s 2006 Site Alteration by-law, which left some older lots directing water in ways that no longer drain well. None of this is your plumbing, it is the surrounding land and infrastructure, which is why grading and a working sump pump matter so much in established Oshawa neighbourhoods.

• 4. Why does my Oshawa basement seep water even without a burst pipe?

  Because the water is coming from outside the foundation, not from a fixture. Oshawa’s glacial till and clay soil drain slowly and hold moisture, so after rain or snowmelt the ground around your foundation stays saturated. That builds pressure that pushes water through small foundation cracks, cold joints, and porous concrete, which shows up as damp walls or seepage with no leaking pipe in sight.

  The fix is about managing groundwater rather than repairing a pipe, so it usually comes down to grading, sealing, weeping tile, and a sump pump. A water leak detection visit confirms it is groundwater and not a hidden supply line, and pinpoints where it is getting in.

• 5. Does Oshawa's glacial till and clay soil affect my drains and foundation?

  Yes, in two ways. For your foundation, the glacial till and clay common across Durham drain slowly and hold water, so after rain or snowmelt the ground stays saturated and presses against the foundation walls, driving moisture in through any crack or weak point. Water can pool against a foundation for extended periods in this kind of soil.

  For your drains, the same clay expands and contracts with moisture through the seasons, and that ground movement can crack, shift, or sag underground drain lines over time, which slows flow and traps debris until a backup develops. A sewer line video inspection shows whether your line has shifted or cracked, so any repair targets the actual condition of the pipe.

• 6. Why does water pool against my foundation during spring thaw and snowmelt?

  Over winter the ground builds up a heavy snowpack, and when temperatures rise quickly the melt combines with spring rain and saturates Oshawa’s clay and glacial till faster than the ground can drain. Because that soil absorbs so little, the water collects against the foundation, especially on flat lots or where the ground slopes toward the house.

  Nearby creeks can also rise with the melt, raising the local water table and adding to the pressure. The defences that matter most are grading that moves water away from the house, clear window wells, downspouts that discharge well away from the foundation, and a sump pump that can keep up, ideally with a battery backup since thaws often coincide with storms and power outages.

• 7. My Oshawa home is a newer build in a growing area. Why am I already seeing drainage problems?

  Newer does not always mean problem-free, and this comes up in Oshawa’s growing north-end areas. The ground around a newer home keeps settling for years, which can shift or create low spots in drain lines, and the disturbed soil backfilled against the foundation drains differently from the surrounding clay, so water collects there. Flat lot grading and construction debris in the lines add to it.

  Combined with Durham’s slow-draining clay, that is enough to cause leaks or slow drains in a home only a few years old. A camera inspection shows whether it is a settled line, a partial blockage, or grading that needs adjusting. If the home is still under builder warranty, check what it covers before any work.

• 8. Why do pipes freeze in Oshawa homes during winter?

  Oshawa winters get cold enough that water sitting in poorly protected pipes can freeze, expand, and split the pipe. The ones most at risk run through unheated or poorly insulated spaces, garages, crawl spaces, attics, and exterior walls, along with outdoor hose bibs and any line near a draughty gap.

  Homes left at low heat while owners travel in winter are especially vulnerable, since an interior wall can quietly drop below freezing. Insulating exposed pipes and keeping a trickle of water moving on the coldest nights both help. If a pipe does freeze or burst, shut off your main water valve first and call for help before the thaw floods the space.