Flood prep checklist
Updated August 2026
Flood prep is about keeping water out and moving it back out fast: a sump pump with a battery backup, backwater (check) valves on drains so the sewer cannot push back in, utilities and valuables raised above expected flood height, and grading that slopes away from the house. The stakes are steep, just one inch of water can cause about $25,000 in damage, and standard homeowner's insurance excludes flooding, so a separate flood policy is part of the plan. Pair this with the hurricane prep checklist if you are on the coast.
| Task | Interval | Effort |
|---|---|---|
| Add or test a sump pump with battery backup | One-time, test quarterly | $150–400 · DIY/pro |
| Install backwater or check valves on drains | One-time | $150–1,000 pro |
| Extend downspouts and slope soil away 6 feet | One-time | $100–500 DIY |
| Task | Interval | Effort |
|---|---|---|
| Elevate the furnace, water heater, and panel on platforms | One-time | $500–3,000 pro |
| Move valuables and documents off the basement floor | One-time | 1 hour · DIY |
| Task | Interval | Effort |
|---|---|---|
| Clear gutters, drains, and window wells of debris | Each event | 1 hour · DIY |
| Stage sandbags or flood barriers at low doors | Each event | $1–3 per bag |
| Task | Interval | Effort |
|---|---|---|
| Buy or confirm flood coverage (30-day waiting period) | Yearly | $700–1,500/yr |
What neglect costs
Water is merciless. FEMA figures put the damage from just one inch of water at roughly $25,000, and a foot in a finished basement can run well past $50,000 once you count drywall, flooring, HVAC, and mold remediation. A sump pump that fails during the storm, because it had no battery when the power died, is the classic cause of a flooded basement, a $10,000–30,000 recovery. Standard homeowner's insurance pays none of it; flood coverage is separate and has a 30-day waiting period, so it cannot be bought once the forecast turns.
Leave these to a pro
You can extend downspouts, regrade soil, and drop in a backup pump yourself. Bring in a pro for the plumbing and electrical: a backwater valve tied into the sewer line ($150–1,000 depending on access) and raising the furnace, water heater, and panel above flood level ($500–3,000). A licensed electrician should handle anything near the panel, because wet electrical is a fatal hazard. And treat a flood-insurance agent as part of the crew, since that policy is the only thing that pays for a cleanup a standard homeowner's policy refuses.
This whole checklist ships as reminders in OnOtto: every task above, on the right schedule for your home, snooze-proof.
Load this checklist as remindersFrequently asked questions
Does homeowner's insurance cover flooding?
No. Standard homeowner's policies specifically exclude flood, defined as rising surface water, storm surge, or overflow. You need separate flood insurance, through the National Flood Insurance Program or a private insurer, and there is typically a 30-day waiting period before it takes effect. That means you cannot buy it when a storm is already in the forecast. Even outside a mapped high-risk zone, a large share of flood claims come from moderate- and low-risk areas, so coverage is worth pricing.
Do I really need a battery backup for my sump pump?
Yes, because floods and power outages arrive together. The heavy storm that overwhelms your pit is exactly when the grid goes down, and a pump with no power is just a hole in the floor. A battery-backup or water-powered secondary pump keeps discharging for hours without utility power. Budget $150–400 for the backup unit and test the whole system quarterly by pouring in a bucket of water. Replace the backup battery every 3 to 5 years.
What is a backwater valve and do I need one?
A backwater valve is a one-way gate on your sewer or drain line that lets waste flow out but slams shut if the municipal sewer surcharges and tries to push water and sewage back into your basement. In areas prone to sewer backup during heavy rain, it is one of the best protections you can install, roughly $150–1,000 depending on access. Some cities even subsidize it. A plumber sizes and installs it; keep the cleanout accessible for maintenance.
How do I protect a basement from flooding?
Layer the defenses. Outside, grade the soil to slope away, extend downspouts at least 6 feet, and keep window wells and drains clear. Inside, run a sump pump with battery backup, add a backwater valve, and seal obvious foundation cracks. Raise the furnace, water heater, and electrical panel onto platforms, and keep valuables off the floor. No single step stops a serious flood, but together they turn a catastrophe into a manageable cleanup.