What to do when your basement floods

First, make it safe

Water and electricity are the real danger in a flooded basement. Do not step into standing water if it has reached outlets, extension cords, the furnace, the water heater or the electrical panel.

• If the panel is upstairs or you can reach it from a dry area, switch off the basement circuits.
• If you cannot reach it safely, call your electrical utility and ask for a disconnect.
• If you smell gas, leave the house and call your gas utility from outside.

Work out where the water is coming from

What you do next depends on the source.

• A burst pipe or failed appliance: shut the main water valve.
• A floor drain or toilet backing up: stop using water in the house. This is sewage and needs different handling. See sewage backup cleanup.
• A failed sump pump: check the breaker and the float. Do not stand in water to do it.
• Water at the wall and floor joint or through a window well: this is outside water. There is little to shut off, so focus on protecting belongings.

Record it before you move anything

Take photos and video of every room, including a shot that shows the water level against a wall or stair. Open cupboards and photograph what is inside. Your insurer will ask for this.

Protect what you can

Move electronics, documents, rugs and furniture legs out of the water if it is safe to be there. Put foil or plastic under furniture feet that must stay. Do not use a household vacuum on water.

Get the water out, then get things dry

Standing water should come out as soon as possible. After that, the wet materials matter more than the puddle: carpet underpad, the bottom of drywall and the insulation behind it hold water for weeks. Mold can begin to grow within 24 to 48 hours in damp conditions.

Call your insurer

Report the loss once the immediate danger is under control. Coverage depends on the source of the water. See what insurance usually covers.

What not to do

• Do not turn the power back on until wet circuits have been checked.
• Do not run the furnace if it was in water.
• Do not throw damaged items out before they are photographed.
• Do not assume it is dry because the surface feels dry.

The first 24 hours, hour by hour

First hour. Safety, source, photos. Nothing else matters until people are out of danger and the water has stopped coming in or you know it cannot be stopped.

Hours one to four. Get standing water out. A pump or wet vacuum on a protected outlet works for shallow water. Deeper water, or anything contaminated, is a job for a restoration crew. Move what you can to a dry floor.

Hours four to twelve. Wet carpet underpad comes out. Baseboards come off so the bottom of the wall can breathe. If drywall is soaked, the wet section and the insulation behind it should be removed, because they will not dry in place fast enough.

Hours twelve to twenty-four. Dehumidifiers and air movers should be running continuously by now, with doors and windows closed so the equipment is drying the room and not the outdoors. This is the window in which mold is prevented or allowed to start.

What it is likely to involve

Most people have never seen a basement restored and imagine either a quick mop-up or total demolition. The usual reality is in between. The floor finish and the lower part of the walls are often lost. The structure, the stairs, the mechanical systems and most hard belongings are usually saved. The room is noisy and warm for the better part of a week while it dries, and then it is rebuilt.

Things people forget

• The furnace filter. Change it once drying is complete. It has been pulling damp, dusty air.
• Under the stairs. A favourite storage spot and a favourite place for hidden wet drywall.
• The cold room. Check it even if the main basement looks fine.
• Receipts. Keep every one, including fans, pumps, bins and meals if you had to leave.
• The neighbours. If several houses flooded, tell the municipality. It supports everyone’s claim.