A heavy rain starts, and for the next hour the water has to go somewhere. Off the roof, across the lawn, down along the foundation, and into the sewer. Most basement floods happen when one of those steps fails. The good news is that each step can be checked and fixed.
This guide follows the water from the roof to the sewer, so you can find the weak link in your home’s drainage before the next storm does.
The short answer: start at the top. Clean gutters, long downspouts and sloping soil fix more basements than any machine. If water still gets in, the problem is lower down: the drain at the foundation, the sump pump, or the sewer line.
Follow the water: four layers of drainage
Think of your home’s drainage as four layers. Each one hands water to the next, and each one can fail on its own:
Check: Gutters are clear, and downspouts empty well away from the house.
Fix: Cleaning, and downspout extensions.
Our price: mostly a DIY job.
Check: The soil slopes away from the wall, and nothing pools beside it.
Fix: Regrading, or a French drain.
Our price: French drain, $25 to $450 per linear foot.
Check: Damp walls or floor, or a sump pump that runs constantly.
Fix: Weeping tile, a sump pump, crack repair.
Our price: weeping tile, $60 to $300 per linear foot. Sump pump, $550 to $3,650.
Check: Slow drains, gurgling, or a smell from the floor drain.
Fix: Drain cleaning, or a backwater valve.
Our price: drain cleaning, $150 to $800. Backwater valve, $1,500 to $3,000.
Layer 1: gutters and downspouts
The roof sends a lot of water to the ground in a short time, so this layer matters most. Clean the gutters at least twice a year, in spring and fall, and more often if trees overhang the roof. Look for sagging, cracks and loose joints, and repair them promptly.
Then check where the downspouts empty. If they drop water beside the wall, add extensions that carry it at least 1.5 metres (5 feet) away, and further if the yard allows. Splash blocks at the end of each downspout spread the water out and prevent erosion.
Layer 2: grading and landscaping
Water follows the slope of the ground. The soil next to the house should fall away from the wall. A common rule of thumb is a drop of about 15 cm (6 inches) over the first 3 metres (10 feet). If the soil has settled, add topsoil and slope it away from the foundation.
Plants help too. Deep-rooted native plants absorb water, and a rain garden captures runoff and lets it soak into the ground instead of running toward the house.
If water still pools in the yard, a French drain can carry it away. It is a trench filled with gravel, with a perforated pipe inside, and it typically costs $25 to $450 per linear foot, depending on depth and the type of drain. It is a job for a professional, because the slope and the outlet have to be right.
Layer 3: the foundation
Underground, water collects around the footing and presses on the wall. Weeping tile is the drain pipe at the base of the foundation that carries it away. Old or clogged tile lets groundwater build up. A new installation typically costs $60 to $300 per linear foot.
Where the water goes next is usually a sump pump, which removes it from the basin in your basement. A pump typically costs $550 to $3,650 to install. Test it a couple of times a year by tipping a bucket of water into the pit, and keep your hands out of it. Add a battery backup (typically $1,200 to $1,500), because the storms that flood basements often knock out the power too.
Cracks in the foundation are part of this layer. A small, dry hairline crack is usually cosmetic, but a wide, horizontal or wet one needs a professional. Here is how to tell the difference. Epoxy injection crack repair typically costs $400 to $800 per crack. See crack repair.
Layer 4: the sewer line
The last layer is the one people forget. When the city sewer fills up in a heavy storm, water can push back into your house through the floor drain. A backwater valve closes to stop it, and typically costs $1,500 to $3,000.
Keep the line itself clear, too. Slow drains, gurgling and a smell from the floor drain are warning signs. Sewer drain cleaning typically costs $150 to $800, far less than a sewage backup. In Toronto, a sump pump, backwater valve or battery backup may qualify for a City subsidy. See our guide to the Toronto basement flooding subsidy.
Tick each one as you check it. It takes about 15 minutes.
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Found a problem? Book a free assessment and we will find where the water is going wrong.
When to call a pro
- Water comes through a wall or the floor after rain.
- Water pools beside the foundation even with clear gutters.
- A crack is wide, horizontal or wet.
- The sump pump runs constantly, or fails.
- Floor drains gurgle or back up.
Not sure which layer is failing? Our guide to what you can waterproof on your own sorts the jobs you can do yourself from the ones to leave to a pro.
How Aquatech helps
We start with a free on-site inspection, find which layer is failing, and tell you honestly what the house needs, which may be a simple fix. You get a written, itemized estimate. Every project is backed by a lifetime warranty that transfers to the next owner, and if you have a comparable written quote from a licensed Ontario contractor, we will match it. See what basement waterproofing costs.
FAQs about home drainage and basement flooding
What are the signs that my drainage needs improvement?
How often should I clean my gutters?
How far should downspouts empty from the house?
Will a French drain stop my basement from flooding?
Do I need a sump pump if I have weeping tile?
Can I improve my drainage myself?
Worried about your home’s drainage?
Book a free assessment. We will find where the water is going wrong and give you a written, itemized estimate.fing in Toronto, consult a professional service to assess your needs and recommend the best solutions.
