Your basement is flooding
Do not walk into standing water until you know the power is off.
Is this an emergency?
You’re probably seeing
- Standing water across the basement floor after heavy rain or a thaw
- Water seeping in where the floor meets the wall
- Water backing up out of a floor drain, toilet or washing machine standpipe
- A sump pump that is silent, or running constantly without clearing
- A musty smell and damp patches on the lower walls
What it probably is
A failed or overwhelmed sump pump
The most common cause in a house that has oneWater rising with the pump silent, or the pump running non-stop and losing. A tripped GFCI or a stuck float is common and free to check.
Surface water getting in from outside
Very common, and often fixable above groundFlooding coincides with heavy rain, and the water is clear. Blocked gutters, downspouts discharging at the wall, or ground sloping towards the house.
A sewer or drain backup
Common - and a different, contaminated jobWater coming UP out of a floor drain or toilet, often discoloured and foul-smelling. Frequently affects the lowest fixtures first.
A burst or leaking supply line
Common, and the source is usually findableClean water appearing with no rain, and often a drop in pressure upstairs. A burst pipe or a failed water heater.
Hydrostatic pressure through the slab or walls
Common in older homes - a waterproofing problemSeepage at the floor-wall joint or through cracks after a prolonged wet spell, rather than a single inrush.
What to do before anyone arrives
Decide whether it is safe to go down at all
In most homes the electrical panel, the furnace and the water heater are in the basement. If water is deep enough to reach outlets, appliances or the panel, do not enter.
Never step into standing water to reach a breaker panel. Switch off power to that level from a panel that is dry and accessible, or call your electricity utility and ask them to cut supply. If in any doubt, stay out and make the call.
Work out whether the water is clean or contaminated
Clear water from rain or a supply pipe is one job. Water that came up through a floor drain or a toilet is sewage and carries a health risk, and it needs protective equipment and disinfection rather than a mop.
Do not attempt to clean sewage-contaminated water yourself, and keep children and pets out of the area entirely until it has been dealt with.
Stop the source if it is within reach and safe
For a supply-line leak, shut off the main. For a sewer backup, stop running water anywhere in the house - every flush and every load of laundry adds to it. For surface water, look at where the downspouts are discharging.
Get the water out, then start drying properly
Pump or wet-vacuum the standing water, then move to airflow and dehumidification. The EPA advises that wet buildings and furnishings must be dried within 24 to 48 hours in order to avoid mould growth, and a basement dries slowly because it is cool and enclosed.
Lift what can be saved, and be realistic about what cannot
Get belongings off the floor and out. Soaked carpet and pad, and the bottom of drywall and insulation, usually have to come out rather than dry in place - water wicks upward inside a wall and a dry surface tells you very little.
If the water was contaminated, porous materials it touched should be removed, not cleaned.
Photograph everything, then call
Wide shots of each area and close-ups of damaged items, before anything moves. Then call a restoration company - and note that standard homeowners policies commonly treat sudden internal water differently from groundwater flooding, so report it promptly and let the adjuster classify it.
This is the end of the homeowner sequence. Structural drying of a basement needs equipment, and sewage cleanup needs training.
What it costs to fix
| What it is | Who does it | What decides your bill |
|---|---|---|
| Sump pump reset or replacement | Plumber, or yourself if it is just a tripped outlet | The pump, plus whether a backup system is added |
| Water extraction | Restoration | Volume, access, and how far the water travelled |
| Structural drying | Restoration | Days of equipment on site - usually the largest line |
| Removing soaked carpet, drywall and insulation | Restoration | How much is porous and how high the water wicked |
| Sewage decontamination | Restoration, specialist | Contaminated-category work costs more, and more gets discarded |
| Fixing the cause - drainage, grading, waterproofing | Waterproofing contractor | A planned project. Get more than one opinion |
Cost drivers described qualitatively; no primary source publishes national restoration pricing, and aggregator figures are undated.
The pattern to understand: the emergency work and the permanent fix are separate purchases from separate trades. Extraction and drying stop the damage; they do nothing to stop it happening again. Do not let an emergency visit turn into an unquoted waterproofing project on the same day - once the basement is dry, get competing opinions on the cause.
Can I fix this myself?
A flooded basement is the most electrically dangerous room in a flooded house, because it usually contains the panel, the furnace and the water heater. Do not enter standing water until power to that level is confirmed off. Do not restart a furnace or water heater that has been submerged - gas controls and electrical components that have been underwater need inspection before they are used again.
Reasonable to DIY
- Calling the utility to cut power when the panel is unreachable
- Checking whether a sump pump has simply tripped its outlet
- Stopping water use during a sewer backup
- Moving belongings out of the water once it is safe
- Photographing damage for the claim
Call a pro
- Any entry into water near an energised panel or appliance
- Sewage-contaminated cleanup of any size
- Structural drying of walls, subfloor and cavities
- Inspecting a submerged furnace or water heater before restarting
- Diagnosing and fixing the drainage cause
The EPA gives a usable line for the cleanup itself: a mouldy area under about 10 square feet - roughly a three-foot square - is in most cases a job a homeowner can handle, and beyond that its guidance points you at professional remediation. It also says plainly that people with asthma or weakened immune systems, children and pregnant people should stay out of flood cleanup entirely. The judgement call that matters most, though, is the first one, and it is yours: whether to go down the stairs at all. After that, a small amount of clean water on a sealed floor is genuinely a wet vacuum and a fan. Anything that soaked into walls, anything that came up a drain, and anything deep enough to reach the appliances is professional work - and the drying, not the pumping, is the part that decides whether you have a mould problem in a fortnight.
Sources
Sources last checked
- Mold Course Chapter 2: Why and Where Mold GrowsU.S. Environmental Protection AgencyRetrieved 2026-09-14
- Homeowner's and Renter's Guide to Mold Cleanup after DisastersU.S. Environmental Protection Agency (with HUD, FEMA, NIH and CDC)Retrieved 2026-09-14
Sources for the figures and the legal requirements cited on this page.
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