Flash floods: what to do¶
Emergency numbers differ by country. This page uses 911, the number for the United States and Canada. Many other countries use 112, 999, or another number. Find the number for your country.
A flash flood is a sudden rise of water, often within minutes or a few hours of heavy rain. This page helps you get to safety fast, in a building, on foot, or in a car.
Do this now¶
- Move to higher ground right away. Do not wait to see how bad it gets.
- Leave low areas, dry stream beds, canyons, underpasses, and the banks of rivers and creeks.
- Never walk, swim, or drive through floodwater. Turn around and find another way.
- If you are in a car and water is rising around it, get out and move to higher ground if you can do so safely. If the car is in fast moving water and you cannot get out, stay inside and call your local emergency number (911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom).
- If you are inside a building, go to the highest floor. Do not climb into a closed attic, where you could become trapped.
How fast they form¶
Flash floods can happen with little warning. Heavy rain, a burst dam or levee, or a sudden release of water can send a wall of water down a channel. In dry or hilly places, the storm that causes the flood may be miles away and out of sight.
Land that cannot soak up water is also at risk. Steep slopes, paved city streets, and ground burned by wildfire shed water quickly. Rain that would be harmless elsewhere can become a flood in those places.
Warnings to watch for¶
Weather agencies use two levels. A watch means flooding is possible, so get ready and keep checking updates. A warning means flooding is happening or about to happen, so act now.
Alerts come through phone alerts, radio, television, sirens, and your national weather service (the National Weather Service in the United States). Do not wait for an alert if you see the signs yourself:
- Heavy rain that does not stop
- Water rising fast in a creek, gutter, or street
- Water turning muddy, or carrying branches and debris
- A roaring sound upstream
Never drive into water¶
Most flash flood deaths happen in vehicles. Moving water is far stronger than it looks.
| Depth of moving water | What it can do |
|---|---|
| 15 centimeters (6 inches) | Can knock an adult off their feet |
| 30 centimeters (1 foot) | Can carry away most cars |
| 60 centimeters (2 feet) | Can carry away SUVs and trucks |
You cannot tell how deep water is, or whether the road under it is still there. Barriers on a flooded road are there to keep you out, so do not drive around them. Stay off bridges over fast moving water, which can wash out.
... danger "Turn around, do not drown" If you see water over a road, turn around and find another route. A few seconds of delay is far safer than being swept away.
Canyons, low crossings, and dry stream beds¶
Canyons, narrow valleys, dry stream beds, and low road crossings can fill with fast water even when it is not raining where you stand. Do not camp, park, or hike in them when storms are forecast anywhere upstream.
If you are caught in a canyon or gully, climb the walls or slope to higher ground at once. Move up and away from the channel, not along it. Do not try to outrun the water by following the stream bed.
At night¶
Flash floods are especially dangerous in the dark, because you cannot see rising water, and you may be asleep. If heavy rain is falling and you live or sleep in a flood prone place, keep your phone charged and alerts turned on.
Keep a flashlight and shoes by your bed. If you hear rushing water or get a warning, get up and move to higher ground or a higher floor right away. Do not drive at night through areas where roads may be flooded.
If you are trapped¶
- If you are in a building, go to the highest level. Go onto the roof only if you must, and signal for help from there.
- If you are in a car in fast moving water and cannot escape, stay inside, call for help, and climb onto the roof if water rises inside.
- If you are swept into water, try to float on your back with your feet pointing downstream, and grab something that floats.
... warning "Floodwater is not clean" Floodwater can carry sewage, chemicals, sharp debris, and live electricity. Stay out of it, and stay away from downed power lines.
After the water drops¶
Water can rise again, and roads may be weakened. Wait for officials to say it is safe to return. Do not drive through any remaining water.
In the United States¶
The National Weather Service issues Flash Flood Watches and Warnings, and the slogan "Turn Around, Don't Drown" comes from them. Standard flood insurance usually takes up to 30 days to start, so ask your agent well before a storm.