What to Do in the First 24 Hours After a Flood

The hours immediately after floodwater recedes are critical — for your safety, for your insurance claim, and for limiting the extent of permanent damage to your home. Most homeowners make expensive mistakes in this window: they re-enter too early, skip documentation, or delay mitigation until mold is already growing. This guide covers the first 24 hours in order.

Before You Re-Enter: Safety Checks

Do not enter your home until you've confirmed three things:

1. Power is off at the main breaker or utility: Electrical hazards in flooded homes kill. If you can't physically confirm the main breaker is off without entering the house, call your utility company to cut power from the outside. Do not enter a flooded basement with power on.
2. Structural safety: Look for visible signs of foundation damage, wall bulging, roof sagging, or separated walls before entering. If you see any of these, do not enter until a structural engineer or building inspector has cleared the property.
3. Contamination level: Floodwater is often contaminated with sewage, agricultural runoff, industrial chemicals, and fuel. Category 3 (black water) flooding from sewage backup or external floods requires full personal protective equipment — at minimum: rubber boots, waterproof gloves, and an N95 mask. Never drink tap water after flooding until your utility confirms it's safe.

Hour 1–2: Document Everything

Before removing a single item or a drop of water, photograph and video every affected area. This documentation is the foundation of your insurance claim. Adjusters are not present in the first hours — your photos are the record.

• Photograph waterlines on walls (shows flood depth)
• Photograph every damaged item in place before moving it
• Photograph electrical panels, HVAC equipment, appliances, flooring
• Video walk through each room, narrating damage as you go
• Photograph the exterior: foundation, windows, doors, any debris

Upload photos to cloud storage immediately — phone storage can fail. Text a backup set to a family member. Your insurance adjuster will ask for timestamped documentation of all losses. The more you have, the faster and more complete your claim will be.

Hour 2–4: Contact Your Insurance Company

Call your flood insurance provider as soon as you have documentation in hand. Flood claims are handled separately from homeowner's insurance — confirm you're calling the right number. If you have NFIP coverage, claims go through your policy's Write Your Own carrier (the company that issued the policy) or directly through NFIP.

Key information to have ready: your policy number, the date and cause of flooding, a preliminary damage estimate. Ask for the name of your assigned claims adjuster and get a claim number. Ask your insurer whether you need to wait for an adjuster visit before beginning water removal — most will tell you to begin mitigation immediately to prevent further damage, but confirm.

Hour 4–8: Remove Water and Begin Drying

Mold begins developing on wet materials within 24–48 hours. The clock starts when the water recedes, not when you get around to it. The goal in this window is to remove standing water and begin airflow as quickly as possible.

• Wet-dry vacuum: For shallow standing water. A large wet-dry shop vacuum ($60–150) is the most useful tool you can own for flood recovery. Most water removal in residential flooding can be accomplished with a shop vac.
• Submersible pump: For deeper water (more than 2 inches), a submersible utility pump ($50–120) moves water much faster than a vacuum.
• Industrial fans + dehumidifier: After water is removed, air mover fans and a high-capacity commercial dehumidifier accelerate drying. Professional restoration companies use these — you can rent or buy them.

Remove wet carpeting, padding, and drywall below the waterline immediately. Wet insulation cannot be dried — it must be removed. Leaving these materials in place while drying takes weeks is a mold guarantee.

Hour 8–24: Prioritize Salvage and Mitigation

Once water is removed and drying equipment is running, shift to salvage and secondary mitigation:

• Move valuables: Electronics, documents, furniture, and clothing should move out of the affected area and into dry space. Wet upholstered furniture typically cannot be saved — the interior foam retains water and mold develops from the inside.
• Open walls if needed: If water was above floor level, there may be trapped moisture inside wall cavities. Cutting access panels at floor level allows air circulation inside walls — critical for preventing concealed mold growth.
• Apply antimicrobial treatment: After surfaces are dry, apply an EPA-registered antimicrobial solution to affected concrete, wood framing, and subflooring. This does not substitute for proper drying but reduces mold spore load on surfaces.
• Keep records of all expenses: Every dollar spent on water removal, drying equipment, and mitigation is potentially reimbursable under your flood policy. Keep receipts for everything.

What NOT to Do in the First 24 Hours

• Don't run HVAC through water-damaged ductwork — it spreads mold spores throughout the house
• Don't use a regular vacuum to remove water
• Don't turn on electricity until an electrician inspects the system
• Don't discard anything before documenting it — adjusters need to see damages
• Don't assume your homeowner's insurance covers flooding — confirm with your insurer which policy applies

When to Call a Professional

If flooding involved sewage (gray or black water), you need professional remediation — not DIY. If the waterline exceeded 24 inches, or if flooding was inside finished living space, professional assessment reduces the risk of missed hidden damage. Your insurance claim may actually be processed faster with a licensed public adjuster who advocates on your behalf.

See our complete flood recovery guide for medium and long-term recovery steps, or find certified flood remediation contractors in your area.