Flooded road ahead: 12 inches of moving water can carry off a car, so turn back

Why flood water is so deadly

NWS says people underestimate the force and power of water, and that many flood deaths happen in cars swept downstream. Many of those drownings are preventable. [S1]

• A little water moves a lot. NWS says just 12 inches of rushing water can carry away most cars, and 2 feet can carry away SUVs and trucks. Ready.gov puts it as one foot of moving water can sweep your vehicle away. [S1] [S3]
• It’s deeper than it looks. NWS says flood water may be deeper than it appears and can hide sharp objects, washed-out road surfaces, electrical wires and chemicals. [S2]
• The road may be gone. NWS warns the road under the water may have collapsed. [S1] [S7]
• It happens fast. NWS says a vehicle caught in swiftly moving water can be swept away in seconds, and that water levels and flow can change quickly during a flood. [S2]

At a flooded road

1. Stop before the water. Don’t drive into a flooded roadway. Turn around and find another route. [S2] [S3] [S8]
2. Never go around a barricade. Ready.gov says local responders use barricades to safely direct traffic out of flooded areas. NWS adds that road closed and caution signs are there for your safety. [S3] [S7]
3. Skip bridges over fast water. Ready.gov says to stay off bridges over fast-moving water, which can wash bridges away without warning. [S3]
4. Watch dips and low crossings. NWS describes roads that dip down to a stream channel, and bridges or culverts that can’t pass high flows, as the places where flood water crossing a road makes passage dangerous. [S1]

Waiting out a storm in the car? Our winter car kit guide covers what to keep in the car if a storm strands you.

On foot

Don’t walk through flood water. NWS and Ready.gov both say 6 inches of moving water can knock you off your feet. [S2] [S3]

• Electric shock. Underground or downed power lines can electrically charge the water, Ready.gov says. NWS says to stay out of water that may have electricity in it, and not to go into a basement or any room where water covers the outlets or cords are submerged. [S2] [S3]
• Dirty water. Flood water can be contaminated with sewage or chemicals and carry dangerous debris. [S3] [S7]
• Dry washes and canyons. In dry areas, NWS warns, a thunderstorm several miles away can send water rushing down a canyon or dry riverbed, even where it isn’t raining. [S5]

If water traps you

• In a car in moving water: Ready.gov says stay inside the car. If water is rising inside it, get on the roof. [S3]
• Anywhere in moving water: NWS says move to the highest point you can and call 911 if possible. [S2]
• In a building: go to the highest level. Ready.gov says get on the roof only if you have to and signal for help from there, and don’t climb into a closed attic, where rising water can trap you. [S3]

Watch, advisory or warning?

NWS uses four flood alerts. [S4]

• Flood Watch, be prepared. Conditions are favorable for flooding. It doesn’t mean flooding will happen, but it’s possible. [S4]
• Flood Advisory, be aware. Flooding isn’t expected to reach warning level, but it may cause significant inconvenience and could become dangerous without caution. [S4]
• Flood Warning, take action. Flooding is imminent or already happening. [S4]
• Flash Flood Warning, take action. A flash flood is imminent or happening. If you’re in a flood-prone area, move to high ground immediately. Flash floods can hit areas that aren’t getting rain. [S4]

NWS says flash floods generally develop within 6 hours of heavy rain or another cause, and that cities flood quickly because concrete and asphalt don’t let water soak in. Ground burned by wildfire repels water too, so rain on a burn scar can turn into flooding and mud and debris flows. [S5]

Before a storm

• Know your low spots. NWS suggests asking where water collects on the roads you use most, and what the fastest way to higher ground is. [S6]
• Get alerts. Ready.gov says sign up for your community’s warning system; the Emergency Alert System and NOAA Weather Radio also send alerts. [S3]
• Under a Flood Watch: CDC says fill your gas tank and make sure the car’s emergency kit is ready, in case you need to evacuate. [S8]
• Charge up. NWS says charge phones and radios and keep backup batteries on hand. It also suggests enough food, water and medicine for at least 3 days. [S6]
• If you’re told to evacuate, go. Follow the designated evacuation routes, and don’t drive or walk across creeks or flooded roads on the way. [S3] [S8]

Building that supply? Our emergency water guide covers how much to store.

After the water drops

The danger doesn’t leave with the water. [S7]

• Drive only if you must. Ready.gov says avoid driving except in emergencies, and return home only when authorities say it’s safe. [S3]
• Roads may be damaged. NWS says standing water can hide sharp objects or a collapsed road, and to check local news for road conditions. [S7]
• Generators outside only. NWS lists carbon monoxide poisoning as one of the leading causes of death after storms that knock out power. Ready.gov says use a generator only outdoors, away from windows. Our generator placement guide has the details. [S3] [S7]

What to do now

Pick what’s in front of you and whether you’re driving or on foot. The answer puts the official steps from this page in one place. [S2] [S3] [S4]

Flood driving checklist

Quick answers