Quick Answer
In the event of a sewer backup, immediately stop using water in your home, remove people (including children and pets) from the affected area, turn off the electricity to your basement, if it’s safe to do so, and contact an emergency plumber. Until the blockage is cleared by a professional, don’t flush toilets, run the dishwasher or shower.
Key Takeaways
- Stop all water use the moment you notice a sewer backup or backed up drain
- Never enter standing sewage without turning off power to the area first
- Treat the water as contaminated (Category 3)wear gloves and boots if you must be near it
- Locate your main sewer cleanout before the plumber arrives to save time
- Photograph the damage for insurance before touching anything
- Call a licensed 24 hour plumber this is not a DIY fix
Why a Sewer Backup Happens So Fast
When a sewer system backed up occurs, it is typically caused by a blockage in your main sewer pipe, which is the pipe that conveys sewer water from all of the fixtures in your home to the municipal sewer. If that line becomes partially clogged, the water can only go back up and will back up the lowest point – usually a basement floor drain backing up or a basement toilet.
Common causes of a basement drain pipe backing up include:
- Tree root intrusion into aging clay or cast-iron pipes
- Grease, wipes, or debris clogs deep in the main line
- Heavy rainfall overwhelming municipal sewers (especially in combined sewer areas)
- A collapsed or misaligned pipe section
- A missing or faulty backwater valve
This is important, as this is why the water-use rule works: Each fixture you use increases the water volume in a full system. Less water usage will buy time and will minimize damage until assistance can arrive to reverse the clog.
What to Do Immediately: The First 30 Minutes
1. Stop Using Water Right Away
The one, critical step. No washing machines, showers, or flushing toilets. Each and every gallon pumped down a drain adds to the pressure on the clogged line and backs up sewage back into the house.
2. Keep Everyone Out of the Area
Basement sewage backup conditions are the most contaminated (category 3 water) and can contain E. coli, Giardia and other dangerous microorganisms. Remove children, pets and those with weakened immune systems from the premises completely until the area is professionally cleaned.
3. Check for Electrical Hazards Before Entering
Avoid approaching an electrical panel in standing water. If it is safe to reach the basement from dry ground, turn off the breaker to the basement. Try not to try for your plumber or an electrician, if you can’t get to it without stepping in water.
4. Put on Protective Gear If You Must Be Near It
If required to be in the area (for transporting goods or to inspect the situation) wear rubber boots, gloves and eye protection. Do not allow sewage to come in contact with skin, particularly wounds and abrasions, and wash off as soon as possible if contact occurs.
5. Move Valuables to Higher Ground
Move furniture, electronics and personal belongings out of the way if it is safe to do so. Avoid taking dirty clothes and other materials through clean rooms.
6. Photograph Everything
Take pictures and video of the standing water, damaged walls, floors and possessions with a time stamp before any cleanup action is taken. When it comes to insurance claims of sewer backup basement damage, this documentation is important.
7. Locate Your Main Sewer Cleanout
When the plumber comes, tell him or her if you know where the cleanout is located (it’s typically a capped pipe in the basement, crawlspace or front yard). It reduces diagnostic time, and will frequently become the access point as a way to clear the clog.
8. Call a Licensed Emergency Plumber
Do not wait and do not try to “self repair” on the primary line. Doing your own work on the sewer pipe may only exacerbate the clog and cause problems for other properties. A 24 hour plumber will be able to pinpoint the issue by using a camera and clear the blockage safely.
What NOT to Do in Sewer Backup
| Mistake | Why It’s a Problem |
| Using chemical drain cleaners on a backed up drain | Often pushes the clog deeper instead of clearing it, and creates hazardous fumes near sewage |
| Flushing toilets to “test” the line | Adds volume to an already-blocked system, worsening the backup |
| Entering standing water near live outlets | Serious shock risksewage-contaminated water conducts electricity |
| Trying to snake the main line yourself | Without a camera inspection, you can’t see what’s actually blocking it and cast-iron or clay pipe can be damaged by the wrong tool |
| Ignoring a partial backup because it seems to be draining | It can indicate a partial blockage that will fail completely without warning |
| Running the dishwasher or washing machine “since the toilet’s not affected” | Every fixture shares the same main line using any of them adds pressure |
Expert Tips to Prevent Future Sewer Backups
- Install a backwater valve: This one-way valve lets wastewater flow out but closes automatically to stop sewage from flowing back into your home during a municipal system surge.
- Schedule regular drain cleaning: Routine maintenance catches grease buildup and early root intrusion before they cause a full blockage.
- Avoid flushing wipes, grease, or paper towels: Even products labeled “flushable” are a leading cause of a drain pipe backing up.
- Get a camera inspection if backups are recurring: A basement drain backed up more than once usually points to a structural issue like root intrusion or pipe misalignment that a snake alone won’t fix.
- Consider a sump pump as a companion system: While a sump pump manages groundwater, pairing it with a backwater valve gives your basement layered flood protection.
Trust BOS Plumbing and Drains When It Matters Most
Sewer backup can cause a lot of stress but you don’t need to face it without support. For more than 20 years, BOS Plumbing and Drains has been providing plumber Mississauga, plumber Oakville, plumber Brampton service, homeowner and business services in the GTA, and throughout Hamilton, Milton, Niagara, Cambridge, Toronto, North York, and Etobicoke.
As a trusted 24 hour plumber and plumbing company, BOS Plumbing and Drains offers:
- 24/7 emergency plumbing for sewer backups, backed-up drains, and burst pipes because these problems don’t wait for business hours
- Camera inspections and hydro jetting to accurately diagnose and clear a sewer system backed up without guesswork
- Backwater valve and sump pump installation to help prevent future backups from happening again
- Transparent, upfront pricing with no hidden fees, so you know the cost before work begins
- A 25-year transferable warranty on all sewer and water line replacements
- Licensed, insured, local plumbers who know the GTA’s older pipe systems and municipal sewer patterns
If you’re searching for reliable local plumbers near you, BOS Plumbing and Drains combines fast response times with honest work and fair pricing exactly what you need when sewage is rising in your basement and every minute counts.
Currently having a sewer back up? For emergency plumbing services, please contact BOS Plumbing and Drains at (905) 247-5747 or make an online booking for a free expert consultation.