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What to Do When You Have a Sewer Backup: A Homeowner’s Essential Guide

November 19, 2025
Sewer Backup Emergency Guide | BEST Contractors

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What to Do When You Have a Sewer Backup: A Homeowner’s Emergency Guide

A sewer backup is one of the most stressful—and hazardous—plumbing emergencies a homeowner can face. Raw sewage entering your home brings not only unpleasant odours and property damage but also serious health risks caused by bacteria, viruses, and toxic gases. The key to protecting your home and family is knowing what to do immediately, what NOT to do, and when to call in professionals like BEST Plumbing & Drainage Contractors.

This comprehensive emergency guide walks you through the right steps, common causes, prevention tips, and why professional intervention is essential.


What Is a Sewer Backup?

A sewer backup occurs when wastewater can’t flow properly through your home’s drainage system and reverses back into sinks, tubs, floor drains, or toilets. This can happen anywhere in the home where drainage lines exist.

Backups shouldn’t be ignored—standing wastewater becomes more dangerous by the minute and can spread contamination through floors, walls, and personal belongings.


Step-by-Step: What to Do When You Have a Sewer Backup

1. Stop Water Use Immediately

Stop running water in all areas of your home. That means:

  • Don’t flush toilets

  • Don’t run taps

  • Don’t use showers or appliances like dishwashers or washing machines

Any water you run will add more wastewater to the already overwhelmed system.


2. Keep Family Members (and Pets) Away

Sewage contains bacteria such as E. coli, Salmonella, viruses, and chemical contaminants. Children, seniors, and pets are especially vulnerable.

Avoid the affected area until professionals assess the situation.


3. Turn Off Electricity if Water Levels Are High

If standing sewage water is near electrical outlets or appliances:

  • Turn off power from your breaker panel, NOT from individual switches

  • Avoid stepping into water that may be touching electrical sources

If unsure, wait for professionals—electrocution risk is real.


4. Protect Yourself With Safety Gear if You Need to Enter

If you must enter the area:

  • Wear rubber boots

  • Use gloves

  • Wear a mask

  • Avoid touching your face or skin

Even brief exposure to sewage can cause infection.


5. Identify the Source if Possible

If you can safely inspect the problem, look for:

  • Gurgling drains

  • Slow toilets

  • Water rising in basement floor drains

  • Wastewater backing up into showers or tubs

These clues can help your plumber quickly determine whether the issue is:

  • A main sewer line blockage

  • A stormwater backup

  • A collapsed or damaged pipe

  • Root intrusion

  • Grease or debris buildup

But never attempt to open the sewer line yourself—this can worsen the backup.


6. Call a Professional Plumber Immediately

A sewer backup is not a DIY project. Only trained technicians have the tools and experience to safely clear blockages and disinfect affected areas.

BEST Plumbing & Drainage Contractors provides:

Fast professional service is essential to prevent further contamination and structural damage.


7. Document Damage for Insurance

Before cleanup begins:

  • Take photos

  • Record video

  • Note damaged belongings

Most insurance companies require this documentation, especially for basement backups.


8. Begin Ventilating and Drying the Area (After the Backup Stops)

Once the source is controlled:

  • Open windows

  • Run fans or dehumidifiers

  • Remove wet materials like carpets or cardboard

Standing water promotes mould growth within 24–48 hours.


What NOT to Do During a Sewer Backup

Avoid these common mistakes:

❌ Don’t use chemical drain cleaners

They rarely reach the main blockage and can corrode pipes.

❌ Don’t attempt to snake the line if you’re not trained

Homeowners often push debris deeper or damage the sewer line.

❌ Don’t ignore “small backups”

Slow drains or occasional basement water often signal a bigger problem—even a partial backup is dangerous.

❌ Don’t pump the water outside unless allowed

Environmental regulations in many municipalities prohibit dumping contaminated water.


Why Do Sewer Backups Happen? Common Causes ExplainedSewer Backup Emergency Guide - Sewer Damage Tree Root | BEST Contractors

1. Tree Root Intrusion

Tree roots naturally seek moisture and can enter even tiny cracks in underground sewer lines.

2. Grease & Fat Buildup

Grease solidifies in pipes, creating thick blockages.

3. Collapsed or Aging Sewer Lines

Older clay or cast-iron pipes are prone to collapse or corrosion.

4. Heavy Rain or Snowmelt

Stormwater systems can overflow, pushing water back into home drains.

5. Foreign Objects or Non-Flushable Items

Common offenders:

6. Improperly Installed Plumbing

DIY installations often lead to poor slope or misaligned pipes, increasing backup risk.


How BEST Plumbing & Drainage Contractors Fix Sewer Backups

Sewer Backup Emergency Guide | Hydro Jet Service by BEST Drainage London Ontario

With over 50 years in the industry, BEST uses advanced diagnostic tools and proven repair methods.

✓ Video Camera Inspections

Pinpoint the exact location and cause of the blockage.

✓ High-Pressure Hydro Jetting

Clears grease, sludge, roots, and debris with intense water pressure.

✓ Root Removal & Line Repair

Safe extraction of intrusive roots and replacement of compromised pipes.

✓ Sewer Line Replacement (Trenchless Options Available)

Minimal disruption solutions for major pipe failures.

✓ Sanitization & Disinfection

Ensures your home is safe and free from contamination after cleanup.

✓ Emergency Response

Sewer backups rarely happen at convenient times. BEST’s 24/7 team is ready to act fast.


How to Prevent Future Sewer Backups

1. Schedule Annual Drain & Sewer Line Inspections

Treatment is helpful, but prevention saves money long-term.

2. Avoid Flushing Problem Materials

Stick to the basics: toilet paper only.

3. Install a Backwater Valve

Prevents the municipal sewer line from backing into your home.

4. Maintain Trees and Landscaping

Plant trees away from sewer lines and remove aggressive root systems.

5. Avoid Pouring Grease Down the Drain

Use a container to collect fats and oils instead.

6. Keep Gutters and Storm Drains Clear

Reduce water pressure around your foundation.


When to Call BEST Plumbing & Drainage Contractors

If you notice:

  • Repeat backups

  • Gurgling drains

  • Sewage odours

  • Water around basement floor drains

  • Slow sinks and tubs in multiple rooms

…it’s time to call in professionals.

BEST Plumbing & Drainage Contractors delivers fast, reliable, and safe solutions to protect your home and family—especially during winter and heavy rain seasons when backups are most common. If your sewer has backed up, call us now at (519) 438-6565


FAQ: Sewer Backup Help

1. Is a sewer backup dangerous?

Yes. Sewage contains harmful bacteria and toxins that can lead to illness and property damage.

2. Who is responsible for sewer line repairs—homeowner or city?

Typically, homeowners are responsible for the sewer line from the house to the property line, but policies vary by municipality.

3. Will insurance cover sewer backup damage?

Some policies cover it if you have sewer backup or water damage add-ons. Check your home insurance details.

4. How fast should I call a plumber during a backup?

Immediately. Every minute sewage sits in your home increases health risks and cleanup costs.

5. Can I prevent a sewer backup?

Yes. Regular maintenance, drain cleaning, backwater valves, and responsible flushing habits all significantly reduce risk.

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