Open the window before the water reaches it

If you have ever thought about it — crossing a bridge, passing a flooded road — you may already have a plan for a car in the water. Stay calm, let it fill, and when the pressure evens out the door will open. Some people held that plan, and others corrected it, and the researchers who have put real cars into real water, with people inside, side with the correction.

A sinking car floats for about a minute, and that minute is your way out: seatbelt off, window open, children out, then you. Do not wait for the car to fill, and do not spend the minute on the phone or on the door.

Why the window, and why now

When a car goes into water, the water outside presses on the doors before the inside has filled, and a door cannot be pushed open against it. Some people make that point. A window is different: in the first moments, before the water is up against the glass, the window still works. Researchers who have run more than eighty submersion tests with people inside say both hand-wound and electric windows generally work when a car first enters the water; emergency dispatch guidance puts electric windows at thirty to sixty seconds, and a US motoring association at up to a minute. After that, one person explains what goes wrong: the battery fails under water, and the water pressing on the glass jams it in its tracks.

That is why many people say the same practical thing: if you see trouble coming, open the windows then, while the power still works. And it is why breaking glass is the fallback, not the plan. Others point out that striking glass through water takes strength you may not have, that water slows every swing, and that a crash can leave you without the reach to try.

The whole sequence has a name in the research: seatbelts off, windows open, out immediately, children first. The dispatch version adds two details worth knowing: unlock the doors as you unbuckle, so rescuers can get in, and if a front window will not go, move to the back seat and try a rear side window. The car may float for as little as fifteen seconds or as long as about a minute. Do not spend that time calling for help; the research is blunt that rescue in time is unlikely, and the call can wait until you are out.

The plan that sounds right

Some people give the old plan in full: wait until the water inside is as high as the water outside, and then the door will open. As physics, it is not wrong — once the car has filled, the pressure evens out. As a plan, it is the one the research calls a mistake, and one person says why in plain terms: waiting brings on panic, uses up the air you have, and leaves you escaping from a car that has sunk, with further to come up. One person warns that coming up from deep water without training is hard in itself. A US motoring association calls the waiting plan “deadly advice”.

It keeps one honest place, and only one. If no window will open and none can be broken, the door is the only way left, and it will not open until the car has filled. That is the last resort in the box at the top of this page — not the plan.

If the window will not open

Then you break one, and the kind of glass decides whether you can. The windscreen is laminated — two sheets with a layer of plastic between — and it will not break into a hole you can climb through, so leave it alone. Side windows in many cars are tempered glass, which shatters into small blunt pieces when struck hard at a corner, where it is weakest; one person notes you may still get small cuts. Some people say to pick a large door window rather than a small quarter window at the back, which is harder to break, and one person reminds you to climb out through the opening, not to wrestle the door.

Here is what has changed in cars since people began sharing this advice. A growing number of cars have laminated glass in the side windows too, and a window punch will not break it. How many is where two sources disagree: the 2019 research says that since September 2017, most new vehicles in North America have laminated side windows; the US motoring association’s own testing put laminated side windows in about one in three 2018 models. Your own car is the only answer that matters, and it is printed on the glass: a small label in the bottom corner of each side window says tempered or laminated. If yours are laminated, the window that opens in the first minute is your exit, and your escape tool is for the seatbelt.

Children go first

The research says to help them from the oldest to the youngest; the dispatch protocol says to help each one undo their belt, have them go out through the open window, and push them out ahead of you. One person here notes how easily unbuckling is forgotten in a panic.

Before any of this

The best escape is the one you never need. Moving water is stronger than it looks: the US National Weather Service says about 12 inches of rushing water can carry away most cars, and England’s Environment Agency says 30 centimetres of flowing water is enough to move one. Do not drive into flood water, however familiar the road. Some people say people in some northern states drive across frozen lakes routinely; a car that goes through the ice is a car in the water.

Then two things you can do parked. Read the label on your side windows. And if you carry a tool, sit belted in and reach for it, the way one person suggests trying their headrest: a plan you have rehearsed once in a driveway is faster than one you are reading about.

Who this page is not for

If you came here because you keep locking yourself out of a running car, that is a different conversation that shares these ones, and this page does not carry it. If you are the person on the bank watching a car go in, the page called Drowning is quiet is about helping from outside the water; call the emergency number first. And the honest limit, from one person: none of these tools help someone the crash has knocked unconscious. What to do for a passenger the crash has knocked out is not something this page covers.