A basement sewer backup is one of the most disruptive problems a homeowner can face. Wastewater entering your home brings bacteria, bad odours, and the potential for thousands of dollars in damage. The longer it sits, the more serious the impact on both your property and your health.

At MK Contracting & Demolition, we work with licensed plumbers, restoration crews, and property managers throughout Sarnia, Lambton County, and Southwestern Ontario to help stop the problem, address the underlying cause, and restore affected areas. If excavation is required, we provide the safe, professional digging and backfill needed to get the system flowing again.

What is a Basement Sewer Backup and Why It Happens Here

A sewer backup occurs when wastewater from your home’s plumbing flows in the wrong direction, typically entering through basement floor drains.

In older neighbourhoods around Sarnia and Corunna, sewer lines made of clay or cast iron are more likely to crack or misalign. Tree roots searching for water can enter these openings and create blockages. Heavy storms can overwhelm municipal lines, pushing water back into private systems — a problem especially common in low-lying communities near Lake Huron and the St. Clair River.

Homes without backwater valves are especially vulnerable because there’s nothing to stop the reverse flow during a municipal system overload.

Main Causes of Basement Sewer Backups

Root intrusion is one of the biggest culprits, with roots growing into tiny pipe cracks and expanding over time. Collapsed or badly damaged sewer lines can block flow entirely. Sudden heavy rainfall can overload older municipal systems.

Grease, debris, and non-flushable items flushed or poured down drains can cause gradual build-up inside pipes. Poorly designed basement plumbing or insufficient slope can also make backups more likely.

Warning Signs Before a Backup Happens

Gurgling sounds from drains when you run water elsewhere in the home are often the first warning. Slow drainage across multiple fixtures — not just one sink or tub — indicates a main sewer line issue rather than a localized clog.

A strong sewer odour indoors should never be ignored. Outdoors, soggy spots in your lawn above the path of the sewer line can point to a leak.

Obvious signs include wastewater pooling on the basement floor, water marks around drains, or actual sewage flowing back into the home. At that stage, stop using water immediately to prevent the situation from worsening.

What to Do Immediately

Avoid contact with any wastewater, as it can contain harmful bacteria. If water is near electrical outlets or appliances, turn off power to the basement — but only if it’s safe to do so.

Stop all water use in the home, including sinks, toilets, and showers. Call a licensed plumber to investigate and clear any blockage. If the plumber determines the line is broken or collapsed, excavation will likely be required. That’s when MK Contracting & Demolition steps in to expose the pipe, allow repairs, and restore the site afterwards.

Notify your insurance provider right away. Some policies include specific coverage for sewer backups, but this is often an added endorsement rather than part of standard home insurance.

Cleanup and Restoration After a Backup

The first step is removing any standing water and contaminated materials like carpet, drywall, or insulation. Restoration crews will disinfect and dry the affected area using industrial equipment to prevent mould growth, which can start within 24–48 hours.

Once the basement is safe, attention shifts to fixing the problem that caused the backup. If a section of the sewer line is broken, misaligned, or collapsed, we provide excavation services to access and replace the damaged pipe with modern PVC. Proper slope and bedding are installed to ensure smooth flow.

After repairs or replacement, the trench is backfilled and compacted. Depending on the location, this may be followed by re-grading the yard, laying sod, or reinstating any concrete or asphalt surfaces.

Repair or Replace?

A targeted repair is possible when damage is limited to a small section — for example, a single cracked joint or minor root intrusion. This can often be done quickly and at lower cost.

If the pipe is heavily deteriorated, corroded, or collapsed in multiple spots, replacing the entire line is usually the better long-term option. It prevents repeated blockages and unexpected failures.

In Lambton County, sewer line repairs often cost between $3,000 and $8,000, while full replacements typically range from $3,000 to $10,000 or more depending on depth, length, and access.

Preventing Future Sewer Backups

Annual camera inspections by a plumber can catch early signs of trouble. Removing small roots before they become large blockages is much cheaper than a major repair.

Installing a backwater valve can stop municipal water from reversing into your home during heavy rainfall. Some local municipalities offer rebates for this upgrade.

Replacing older clay or cast iron pipes with PVC removes the brittleness and vulnerability to root damage. Practicing good drain habits — such as keeping grease and wipes out of sinks and toilets — also reduces the risk.

Why Homeowners and Trades Choose MK Contracting & Demolition

Plumbers across Southwestern Ontario trust us for excavation and backfill when they uncover a problem that can’t be solved from inside the pipe. We’re equipped for tight-access digs, hand excavation near utilities, and emergency response when backups threaten homes and businesses.

We also work closely with property managers handling rental units, insurance restoration contractors managing flood recovery, and municipal public works departments addressing urgent infrastructure issues.

Our service area includes Sarnia, Bright’s Grove, Point Edward, Corunna, Wyoming, Petrolia, Oil Springs, Watford, Forest, Grand Bend, Thedford, Camlachie, and surrounding communities.

Get Help for a Basement Sewer Backup

If you’re dealing with a basement sewer backup in Sarnia or nearby towns, quick action is critical. MK Contracting & Demolition can coordinate with your plumber, provide excavation to fix the problem at its source, and help restore your property so it’s safe to live in again.

We offer 24/7 emergency response across Lambton County and Southwestern Ontario. Contact us today for immediate help.

Sponsored by MK Contracting & Demolition