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Sewer backup insurance: knowing your costs and risks

Tyler Wade

Sure, I’ll clean a flood. But no one wants to clean a sewer backup in their home. Exposure to sewage poses severe health consequences, and hiring professionals is expensive, from clean-up to renovations. 

A sewer backup and the resulting water damage is the number one insurance claim in Canada, and costs vary widely. 

With that in mind, let’s look at what causes a sewer backup, how to prevent it, early warning signs, and how home insurance will (or won’t) cover you. 

What is a sewer backup?

Sewer backup is when wastewater flows back into your house from the city’s main sewer lines. The sewage typically seeps up into your basement through your floor drains.  A sewer backup can also occur when there is a blockage in your plumbing or sewage systems.

What causes a sewer backup? 

There are many ways a sewer can back up into your home, including: 

  • Heavy rains or melting snow overflowing the city’s main drains
  • A failed sump pump (e.g. power outage, no backup battery)
  • Ageing sewer systems or lines that have broken or collapsed (e.g. clay pipes)
  • Cracked or deteriorating city lines (e.g from tree roots)
  • Blockages in city sanitary lines or plumbing inside your home

Signs you may be at risk of a sewer backup

You should call a licensed plumber if you see any of the following: 

  • Basement toilet backing up
  • Sewage backup in bathtub
  • Sewage backing up in basement drain
  • Toilet won’t flush after rain and plunging doesn’t help
  • Foul smell from drains
  • If your toilet or sink “bubbles” more than once
  • Back to back toilets clogged
  • Several plumbing fixtures drain slowly (or clogged)
  • The washing machine doesn’t drain or backs up into the toilet or bathtub

How to prevent a sewer backup in your basement?

It’s a multi-part answer because it depends on the problem (which is hard to figure out). So, here are some things you should do to prevent a backup, but also to prevent flooding. 

Don’t flush down the drain line

  • Coffee grinds (put in green bin or garden)
  • Do not pour grease down the drain. For bacon grease, fats, or cooking oils, use a separate container until it congeals, then wipe up with a paper towel and put into green bin or garbage. 
  • Don’t flush paper towels, wipes (even if it says they’re flushable), diapers, cigarette butts, or feminine products down the toilet. 
  • Use garbage disposal correctly – run water before and after use to wash food waste away.

Direct water away from your house

  • Ensure downspouts are at least 3ft away from your house (ideally 6ft)
  • Avoid non-porous landscaping (e.g. concrete, asphalt) and use grass or flowerbeds instead
  • Consider rain barrels or french pits
  • Ensure your downspouts and weeping tiles are not connected to the city main drain

Install a backwater valve

A sewer backup valve is like a toilet backflow prevention device. It’s a plastic box that attaches to your main underground drain out to the city main drains. Normally, this box operates just like an extension of your drain. If the city main drain backs up, though, you’ll be happy knowing you’re protected. When enough water flows into your house, the sewer backup valve lifts up preventing any water from flowing in or out. 

A sewer backup valve should have an access point under your basement floor. If you’re in your basement, think about where all your bathrooms are – the backflow preventer will be between the bathroom closest to the street and the street itself. 

Check for subsidy programs through your city, here is Toronto’s program that offers $3,400 for a backwater valve and a sump pump. 


Get a sump pump installed

A sump pump sucks in water into a sump pit and shoots it out into the soil below the basement. If you live in a low-lying area where you’re at high risk of flooding, it can be a lifesaver. Check them regularly, they typically last 10-15 years. A sump pump is part of a larger system that includes weeping tile and often a french drain. 

Check your sewer drains

For about $99, you can inspect your drains with a professional plumber using a camera. The plumber can also “snake” your drain to clear them out and look for holes or obstructions like tree roots. 

What to do when your sewer backs up?

If sewage backs up into your basement, leave your home as soon as you can. The smell is awful and is toxic to your health. Do not attempt to enter the floodwater, especially with electrical outlets nearby. 

Don’t use any plumbing fixtures like sinks, bathtubs, or toilets until you’ve called a plumber. 

If you can, turn off the main power via the electrical panel. 

Contact your municipality to report the problem and to help determine its cause. 

Once it’s safe to do so, call a plumber to install a sewer backup valve or backflow preventer to avoid this problem from happening in the future. 

Ask the plumber to “snake” the drain. Snaking a drain is the process of clearing a blockage from any drain from something getting lodged in the drain – either from something being improperly being flushed down the toilet, an inadequate slope on your pipe, or a crack in clay piping. 

If your drains are made of clay, you should strongly consider having them replaced with ABS pipe as it can handle the extreme cold and is more resistant to shock. 

If you have a sewer backup endorsement on your insurance policy, you’ll also want to call your home insurance provider to submit a claim and get the mess cleaned up as soon as possible. Including any repairs to your floor, carpets, furniture, baseboards, and drywall. 

Does insurance cover sewer backup?

When I first wrote this article, sewer backup was not standardized. A standard policy from most insurance companies will include coverage from a burst pipe, but not from a sewer backup. Given the rise in flood insurance claims, an insurance broker will always quote sewer backup, but most companies still charge extra for it. 

The cost of sewer backup insurance depends on your provider and the age and location of your house. 

An insurance policy is not a maintenance contract, and if you don’t have a sewer backup valve installed, it could be seen as poor maintenance since you could have done this to avoid the problem in the first place. 

Is sewer backup insurance worth it? 

I reached out to Paul Davis, experts in recovery and remediation following an insured disaster. They said the #1 question is if your basement is finished, how much and type of sewage, and how high up the walls will all play key roles in knowing if sewer backup insurance is worth it. 

Is your basement finished?

A finished basement will increase your costs considerably. To remove and install a new laminate floor could be about $5 per square foot. In a 500 sq. ft. basement, that’s $2,500. But it affects your electrical outlets, your doors, trim, and all your stuff (e.g. couches, appliances, etc.). 

How much sewage water and what kind of sewage water?

Is it kind of clear or a thick sludge? If they can pump it out, it’s cheaper than manually scoping and mopping, but the cost ranges from $1,500 to $3,000 for an average house. A bigger house comes with a bigger repair bill. 

How high is the water?

Oftentimes, after heavy rainstorms, the water can be 3-4ft up the walls. So, you’re removing drywall, insulation, and typically a furnace, too. Those costs can fall between $4,000 to $5,000. 

The average cost of remediation is $30,000. 

The experts told me the majority of people have coverage, but 50% don’t have enough. There’s often a limit of $10,000. They said 10% have full sewer backup coverage with a low deductible and no limits on damages. Read your policy carefully. 

How much does sewer backup insurance cost?

The average cost of adding sewer backup coverage to your insurance policy is between $150-$300 per year. But, it depends on where you live. In an area with a high frequency of claims (such as Black Creek and Eglinton in Toronto), the yearly cost can be as high as $700.

If you don’t have a sewer backup valve, or backflow preventer installed you should add sewer backup insurance to your home insurance quotes to help cover the costs of a flooded basement. 

Do you need sewer backup coverage in a condo? 

If you live in a condo, your condo insurance doesn’t automatically have this endorsement on your policy. 

But, you don’t need it, right? It’s covered by your building insurance which you pay for through your condo fees. 

While that’s true, if there’s a blockage because a neighbouring unit above flushed something down they shouldn’t have, and all the units all day forever flushing down to that blockage, well, the excess will look for a place to escape. The escape will be your bathtub, sinks, and toilets or whatever unit is just above the blockage. 

The building’s insurance may cover a portion, but if you’ve renovated beyond the “standard” or average, consider the endorsement on your policy. 

What about basement apartments?

If you’re renting, tenant’s insurance protects your stuff and covers the cost for you to live elsewhere while the repairs are ongoing. Your landlord’s insurance doesn’t protect a renter’s belongings. A landlord’s insurance policy will repair the damage to the unit, but your valuables and the cost to live elsewhere is on the renter to replace. 

The bottom line

Call your insurance company to see how much it would cost you to add sewer backup insurance to your policy and ask about contents limits. The higher the quote, the more likely you’re in an area with high risk. If you don’t buy the insurance, be sure to get a sewer backup valve and a sump pump installed as soon as possible. The experts at Paul Davis said it’s not uncommon to see 10 insurance vehicles on one street following heavy rainfall or snowmelt.  



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