How much does it cost to clean up a flooded basement in Toronto?

It turns on what the water was. A small clean-water loss caught quickly is $1,000 to $4,000 across three Ontario restoration companies. A finished basement that went under is $7,000 to $20,000. A sewage backup is $5,000 to $35,000, because everything porous it touched is waste rather than something to be dried. Priced by area instead, Ultimate Mold Crew publishes $3 to $10 a square foot and DESA Contracting $4 to $12.

What do Category 1, 2 and 3 water mean, and why does it change the price?

They are the restoration industry's grades for how dirty the water is, and they decide what can be saved rather than just how wet it is. Category 1 is clean water from a supply line: dry it and most things survive. Category 2 is grey water, used or ground water, and porous materials start coming out. Category 3 is black water, which includes sewage, and the rule is that anything porous it touched is removed rather than cleaned. That is why the same volume of water costs three times as much when it arrives up a drain instead of down a pipe.

Will my insurance cover a flooded basement?

Partly, and the gap is where people get hurt. 24/7 Remedial Services notes a deductible of $500 to $2,500 on most Ontario policies, and that sewer backup needs its own endorsement, often capped at $10,000 to $25,000. A Category 3 cleanup at $12,000 to $35,000 can therefore run past the cap on a policy that does cover it. Read the endorsement limit before you need it, not after.

Why is the rebuild quoted separately from the cleanup?

Because they are different jobs done by the same crew, and mixing them is how two quotes stop being comparable. Mitigation is extraction, drying and disinfection. Reconstruction is drywall, flooring, trim and paint, which DESA Contracting prices at $1,000 to $20,000 and up on its own. 24/7 Remedial Services publishes both for a 1,000 square foot finished basement: $6,000 to $14,000 to mitigate, $20,000 to $50,000 and up once the room is rebuilt. Always ask which number you are looking at.

How fast do I have to act?

Same day, and the reason is mould rather than water. Ultimate Mold Crew prices mould remediation after water damage at $1,500 to $6,000 and up, and a warm damp basement gets there in days, not weeks. Every hour before extraction starts is more material that stops being dryable and starts being removable, which moves a job from the drying column into the demolition column.

How do I stop it happening again?

Work out what let the water in, because the fix differs completely. Water up the floor drain is a sewer surcharge and a backwater valve is the answer. Water through the walls or the floor edge is groundwater, and that is weeping tile and a sump pump. Water down a wall in one spot is usually a crack, or a downspout dumping at the foundation outside it. The City of Toronto pays up to 80 per cent toward the first two, capped at $6,650 per property, and that is worth doing before the next storm rather than after it.

What does it cost to clean up a flooded basement?

Last updated: August 26, 2026By Below-Grade Records Desk

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The single biggest factor is not how much water there was. It is what the water was. Clean water from a burst supply line is dried and most of the room survives. Sewage up a floor drain means everything porous it touched is removed rather than cleaned, and the same flooded basement costs three times as much. Pick what happened below.

Price the cleanup

What happened, and what was the water?

A small amount of clean water, one room, caught fastA supply line let go, or an overflow stayed contained. Nothing sat overnight.Category 1, clean waterSeveral rooms, and some material has to come outA burst pipe or an appliance flood that reached more than one room. Baseboard and some drywall are coming off.Category 1 or 2, clean or grey waterThe whole finished basement went underGroundwater or a long-running burst. Flooring, drywall and often the bottom of the framing are gone, and the room is being rebuilt.Category 2, grey waterSewage came back up the drainCategory 3. Everything porous it touched is waste, the space is disinfected rather than dried, and the rules about what can be saved are not negotiable.Category 3, black water

How much floor was under water?

Roughly, in square feet. A typical Toronto basement is 600 to 1,000. This drives the second opinion below, not the main figure.

sq ft

Which of these are also true?

Mould remediationNeeded once it has been damp long enough, which in a warm basement is days rather than weeks.The ductwork got wetWater in the ducts means the system is cleaned or replaced, or it redistributes what was in the basement through the house.Try to save hardwood flooringSpecialised drying mats, added to the drying phase. Sometimes it works.The house is pre-1990, so asbestos testing firstTesting only. Abatement, if it is confirmed, is priced separately and is not in this figure.They came out after hours or on a holidayFloods do not keep business hours and the callout is charged accordingly.

What this cleanup costs in the GTA

$9,605–$29,380

with 13% HST. Before tax that is $8,500–$26,000.

Cleanup and drying: the whole finished basement went underProLine Restoration; 24/7 Remedial Services; DESA Contracting: $7,000–$20,000
Mould remediationUltimate Mold Crew: $1,500–$6,000
HST at 13%Government of Ontario: $1,105–$3,380

The second opinion, priced by area. Ultimate Mold Crew and DESA Contracting publish water damage work at $3.00–$12.00 a square foot, which on 700 sq ft is $2,100–$8,400 before tax. That figure is worked out separately and is not added to the total above; it is there so two independent methods can disagree in front of you.

What insurance does with it. A deductible of $500–$2,500 applies on most Ontario policies (24/7 Remedial Services). This kind of loss usually needs a sewer-backup endorsement, and those are commonly capped at $10,000–$25,000. If the estimate above runs past the cap, the difference is yours.

Two published figures at other scopes. $2,500–$10,000 per job for basement water damage in Toronto, all severities (Ultimate Mold Crew). $6,000–$50,000 per job for finished basement of about 1,000 sq ft: mitigation only, then with reconstruction (24/7 Remedial Services). Neither is folded into the estimate, because neither describes the single severity you picked.

Ranges are the published prices of four named Ontario restoration companies, widened where they disagree and never averaged. Drying and rebuilding are frequently two separate quotes: DESA Contracting prices complete reconstruction at $1,000 to $20,000 and up as its own line. Ask which of the two you are being quoted for.

Method

How is this estimate built?

Four Ontario restoration companies publish severity-banded price tables, and WaterproofingIndex read all four in August 2026. The calculator matches your situation to the band each company describes, takes the lowest low and the highest high across them, adds the extras you ticked and applies 13 per cent HST.

The per-square-foot figure is worked out separately and is deliberately never added to the total. Ultimate Mold Crew and DESA Contracting both publish an area rate, and an area rate and a job-size band are two ways of pricing the same work rather than two parts of it. Adding them would double the bill. Side by side they are a check on each other, and a real quote that sits far outside both is worth a second opinion.

Two published figures are shown beside the answer but kept out of the range: Ultimate Mold Crew's $2,500 to $10,000 covers basement water damage at every severity at once, and 24/7 Remedial Services' 1,000 square foot basement figures split mitigation from reconstruction. Neither describes the one severity you picked, so neither is allowed to move a bound.

Questions

Before the crew arrives

Photograph everything before anything moves. Water line on the wall, the contents, the floor. That is the evidence your claim rests on and it stops existing the moment extraction starts.
Ask whether the quote is mitigation or reconstruction. It is the single most common reason two restoration quotes are not comparable.
Find out your endorsement limit today. Sewer backup is frequently capped well below what a Category 3 cleanup costs.
Ask what equipment is staying, and for how long. Drying is billed by the day and by the machine. The number of air movers and the number of days is most of the drying line.
If the house is pre-1990, raise asbestos before demolition. Testing is $150 to $400. Finding out afterwards is not.

Prices

Stopping the next one

Cleanup is the expensive half of a problem whose cheap half is prevention, and the right prevention depends entirely on how the water got in. If it came up the floor drain, that is the municipal sewer surcharging and a backwater valve is the fix. If it came through the walls or the floor edge, that is groundwater and the answer is drainage and a pump. If it ran down one wall in one place, look for a crack, and then look outside that spot for a downspout.

The City of Toronto pays up to 80 per cent of the invoiced cost toward the first two, to a ceiling of $6,650 per property, through its Basement Flooding Protection Subsidy Program. Against a $20,000 cleanup and a $2,500 deductible, that is not a close call.

Frequently asked questions

How much does it cost to clean up a flooded basement in Toronto?: It turns on what the water was. A small clean-water loss caught quickly is $1,000 to $4,000 across three Ontario restoration companies. A finished basement that went under is $7,000 to $20,000. A sewage backup is $5,000 to $35,000, because everything porous it touched is waste rather than something to be dried. Priced by area instead, Ultimate Mold Crew publishes $3 to $10 a square foot and DESA Contracting $4 to $12.
What do Category 1, 2 and 3 water mean, and why does it change the price?: They are the restoration industry's grades for how dirty the water is, and they decide what can be saved rather than just how wet it is. Category 1 is clean water from a supply line: dry it and most things survive. Category 2 is grey water, used or ground water, and porous materials start coming out. Category 3 is black water, which includes sewage, and the rule is that anything porous it touched is removed rather than cleaned. That is why the same volume of water costs three times as much when it arrives up a drain instead of down a pipe.
Will my insurance cover a flooded basement?: Partly, and the gap is where people get hurt. 24/7 Remedial Services notes a deductible of $500 to $2,500 on most Ontario policies, and that sewer backup needs its own endorsement, often capped at $10,000 to $25,000. A Category 3 cleanup at $12,000 to $35,000 can therefore run past the cap on a policy that does cover it. Read the endorsement limit before you need it, not after.
Why is the rebuild quoted separately from the cleanup?: Because they are different jobs done by the same crew, and mixing them is how two quotes stop being comparable. Mitigation is extraction, drying and disinfection. Reconstruction is drywall, flooring, trim and paint, which DESA Contracting prices at $1,000 to $20,000 and up on its own. 24/7 Remedial Services publishes both for a 1,000 square foot finished basement: $6,000 to $14,000 to mitigate, $20,000 to $50,000 and up once the room is rebuilt. Always ask which number you are looking at.
How fast do I have to act?: Same day, and the reason is mould rather than water. Ultimate Mold Crew prices mould remediation after water damage at $1,500 to $6,000 and up, and a warm damp basement gets there in days, not weeks. Every hour before extraction starts is more material that stops being dryable and starts being removable, which moves a job from the drying column into the demolition column.
How do I stop it happening again?: Work out what let the water in, because the fix differs completely. Water up the floor drain is a sewer surcharge and a backwater valve is the answer. Water through the walls or the floor edge is groundwater, and that is weeping tile and a sump pump. Water down a wall in one spot is usually a crack, or a downspout dumping at the foundation outside it. The City of Toronto pays up to 80 per cent toward the first two, capped at $6,650 per property, and that is worth doing before the next storm rather than after it.

Sources

Where these numbers came from

Four Ontario restoration price lists plus the City of Toronto's subsidy page, each read on its own page in August 2026 and stored with the sentence carrying the figure. Canadian dollars, before HST.

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