How to Handle Emergency Basement Flooding

Basement flooding can happen suddenly, after heavy rain, a burst pipe or a fast snowmelt. When it does, acting in the right order matters, because the first few hours decide how much damage you have, and whether mold and foundation problems follow. Your safety comes first, then the water, then the repair.

This guide walks you through seven steps, shows how to judge how bad it is, and tells you when to call for help.

If water is coming in right now: stay out of it if it is near outlets or appliances, and call us on 647-794-1701 or 866-620-8492. We answer emergencies 24/7. See emergency waterproofing.

Key takeaways

• Safety comes first. Water and electricity are a deadly mix, so stay out of the water if it is near outlets.
• Find the source. A burst pipe, a sewer backup and groundwater each need a different response.
• Remove water in the right way. Pumps and wet/dry vacuums work, but deep water needs a gradual approach.
• Call early. For serious flooding, contaminated water or structural damage, professionals save time and money.
• Fix the cause. Without waterproofing and drainage, the next storm does it again.

How bad is it? Three levels

The cards below match what you see to the right response. When in doubt, treat it as the more serious level.

Make it safe first

Before you do anything, check for hazards. Water can carry electricity, bacteria and sewage, and it can hide damage to the structure.

• Keep out of the water near electricity. If water reaches outlets, appliances or the panel, don’t wade in to switch anything off. If you can reach the main breaker from a dry spot, switch it off. Otherwise, call an electrician or your utility, and wait outside.
• Check for gas. If you smell gas, leave the house at once, and call your gas utility from outside.
• Wear protection. If you have to enter, wear rubber gloves and boots. Floodwater can carry bacteria, sewage and other contaminants.
• Keep children and pets away. They shouldn’t go near the water.

Find the source

Once it is safe, work out where the water comes from, because each source needs a different fix.

• A burst pipe or an appliance. Shut off the water supply at the main valve. See drain repair services if a drain is involved.
• Sewage from a floor drain. The sewer may be backing up, so treat the water as contaminated. A backwater valve stops it next time.
• Groundwater through walls, cracks or the floor. It usually follows heavy rain or a thaw. See wet basement repair and basement leak repair.
• A window or a window well. Water pours in when the well overflows. See leaking window wells.

Our guide to how to determine the source of moisture helps if it isn’t obvious.

Remove the water

The longer water sits, the more damage it does to carpets, drywall and furniture. So start removing it as soon as it is safe to do so.

• A pump works for deeper water. A submersible pump, or your sump pump, moves large amounts quickly. Never run a gas-powered pump indoors, because of the carbon monoxide.
• A wet/dry vacuum handles smaller amounts from floors and carpets. A household vacuum isn’t safe on water.
• Towels and mops are fine for a small spill, but too slow for a real flood.

If the basement is deeply flooded, and the ground outside is saturated too, ask a professional before you pump it all out at once. Removing the water too fast can stress the walls. See what to do if your sump pump overflows.

Dry the basement out

After the standing water is gone, drying prevents mold, which can start growing within a day or two.

• Run dehumidifiers and fans. They pull moisture out of the air faster than ventilation alone, and opening windows during a storm can bring more humidity in. See humidity levels in your basement.
• Remove what can’t be saved. Soaked carpet, insulation and drywall hold moisture, and they feed mold. Photograph them first.
• Lift what can be saved. Move furniture and boxes onto blocks, off the damp floor.

Check for damage

When the area is dry, inspect it carefully.

• Look for mold. Check walls, ceilings, flooring and corners, and notice any musty smell. See harmful mold and mildew.
• Look at the structure. Cracks, bowing walls and a floor that has shifted need a professional look. See the types of foundation damage.
• Document everything. Photograph and film the damage, and keep the receipts. Your insurer will ask.

Call the right people

Different problems need different specialists, and the order helps.

• Your insurer, early. Ask what your policy covers. Many policies treat sewer backup and groundwater as optional add-ons. See whether waterproofing is covered by insurance.
• Your city, for sewer backups. Report them, and in Toronto, call 311.
• A restoration company for water extraction, drying and mold cleanup after a big flood.
• A plumber if a pipe or a fixture caused it.
• Aquatech if groundwater caused it, and to stop it happening again. We answer 24/7: see emergency waterproofing.

In a flooded basement: do and don’t

The short list below sums up the key points. Keep it on your phone.

Prevent the next flood

After the emergency, deal with the cause, because the same weather will return.

• Install or upgrade a sump pump, with a battery backup. A sump pump typically costs $550 to $3,650, and a battery backup $1,200 to $1,500.
• Add a backwater valve if the sewer backs up. It typically costs $1,500 to $3,000.
• Waterproof the basement. Interior waterproofing typically costs $69 to $190 per linear foot, and exterior waterproofing $110 to $500.
• Clear the gutters and slope the soil away. See how gutters affect waterproofing and improving your home’s drainage.
• Fix cracks and window wells. See epoxy injection crack repair and window well installation.

In Toronto, the City subsidy may cover part of a pump, a backup or a valve: see our guide to the subsidy.

What it costs

Emergency waterproofing typically costs $500 to $3,500, depending on what has to be done. After that, lasting fixes are priced by the job: interior waterproofing typically $69 to $190 per linear foot, exterior waterproofing $110 to $500, and crack repair $400 to $800 per crack. Only a free on-site estimate gives you a number for your house. See our cost guide.

Conclusion

Handling an emergency basement flood takes quick action, clear thinking and a focus on safety. If you follow the steps in order, you limit the damage, and you reduce the risk of mold and structural problems. We have spent nearly 30 years dealing with floods like this, and a lifetime warranty backs every Aquatech project. Remember to call a professional for serious flooding, contaminated water, or when the source isn’t clear. See also our guide to basement flooding in Toronto.

Frequently asked questions

Is your basement flooding right now?

Call 647-794-1701 or 866-620-8492, and we will answer. You can also book a free assessment after the emergency, to find the cause and get a written, itemized estimate.