What to do in a car in water

Have you heard the advice that if your car ends up in deep water that you should: “leave doors and windows shut – wait till the pressure equalises and” … well basically drown because that’s what will happen if you follow that advice.

I’ve been studying fording over rivers and as a result I’ve been watching many videos of river incidents. And I’ve come across these Youtube videos giving the “right” advice … but having watched 100s of incidents involving cars in water, I feel the advice may be less than helpful in the type of incidents that really occur. People do drown in deep water – but usually the incidents causing deaths start in shallow water where it doesn’t seem obvious to open the window, very few do so and the advice to “open windows if you drive into deep water” is not going to help.

The Myth of Equalising Pressure

The problem is that until all the air that can escape does so, there will be an inward pressure on doors and windows and this will jam them preventing them being opened. You would be able to open the doors when the last bit of air leaks out … but that takes so long that you will likely drown.

Myth Busters provides a very good demo of this. So lets see what does happen if you follow the advice of not opening doors and windows (a demo from mythbusters Adam):

Note, Adam had time to think through what he was going to do, he also is professionally resourceful guy who has a lot of experience breaking glass. He was uninjured … but without the breathing apparatus he would have died.

Why it’s critical to get the car windows open

This first video shows a reporter trying to back up a claim that “all it takes is a matter of seconds to get into your vehicle … all they need is a hammer”. (Remember he has many takes … you’d just have one).

Similarly this composition video shows that even those who set out intentionally to break windows having preselected tools they think are right for the job are likely to fail:

But it is also surprising easy to break a car window

The reason I think the above techniques failed is because glass is relatively good at absorbing a relatively slow blow from a relatively blunt object – which when the object is quite heavy. This is because is bends and absorbs the blow. However, if you can deliver a very quick blow from a small dense object the glass cannot absorb the blow but instead (with luck) the glass will break:

So there is just a slim hope that if you can hit a side window (or one already damaged) fast enough with something hard or metallic that it will shatter. So you might try tying keys to stocking, putting money in socks or whirling a belt around your head. But that may not work when the water reaches the window outside and it will certainly be impossible to get enough speed when the inside is filled.

So the right advice advice if you were land up in deep water is to open windows

Indeed, the best advice is:

  1. Not to get into deep water
  2. But if you think it at all possible – to wind down your window well in advance (such as when crossing a ford or flooded section of road).

However, whilst I would like people to know to wind down windows (ideally before any chance of) entering deep water, that kind of accident is so rare that the only people talking about it are those with a water phobia and those trying to con people to buy special hammers to get out of your car.

Indeed, even if you bought one of those special hammers or devices that will supposedly break glass – it will likely be dark, you’ll be disorientated , everything will be flung about the car and I think there’s almost no chance you’ll be able to find it in time to use it. Indeed as the video in this news report shows … some of these hammers are useless.

The reality of vehicles in floods

The following is a pretty good summary of the kinds of things that happen to cars in water:

  1. It starts showing a car designed to go through deeper water driving past another that presumably either stalled or was parked.
  2. Like all the other cars that have floated, it was clearly floating in the “bobbing duck pose”: backside up and wheels down – usually with the front sitting on the bottom. The front down is clearly due to the engine weight, I presume cars tend to be bottom heavy.
  3. Contrary to the videos about “how to get out of a car in deep water”, the video shows that most cars ending up in water actually float and bob along for a while. This may be because trials of how long it takes a car to sink have used older or damaged models whereas the cars that I’ve seen on video are invariably the newest and most expensive (people seem to take delight seeing expensive cars floating away).
  4. However, most cars also end up in water that is not deep enough to sink them entirely. Even where they do enter something like the sea or lake, it’s normally from the edge where its still shallow. As such most cars that float end up like those shown in the video – nose down with the back being supported – if you can’t get out – that’s your best chance of survival!
  5. The other thing as shown by the girl falling in – is that deep water can be extremely local. You may think the road is just a few inches deep – then you arrive at a part where a storm drain under the road has failed and the road is just one big hole into which the car falls.

However, the main thing is that most victims in cars will start up like the video below. It’s raining – they don’t want to open the windows for obvious reasons, and the flooding is not suddenly descending into deep water but a very slow descent. At what point would you open the window?

After watching an enormous number of videos, this I think is as you will get to what it really like in a car as one of these incidents develop. Usually someone is crossing flood water and the water is deeper or faster than expected, the road has collapsed or the water rises rapidly in a flash flood (usually in dry areas so not the UK).

Note that not one car had their windows open. And for very obvious reasons. It was raining, the noise of the rain was terrifying … and they were safe (for a while) in the car. But all that time they were talking about what to do, the water is getting into the electric – and it is only a matter of time before electric windows fail. And if the car is already floating, the doors will already be difficult to open and water will be starting to come in. These people were lucky that they did not get picked up by the current into a much deeper flow!

But … given the amount of debris in the water … I agree that trying to wade through that fast water could be extremely dangerous. And here is another problem with the advice to “get out as soon as possible”. Yes, open a window to provide an escape route, yes if you get into really deep water you’re much better off on the car than in it. But flood water invariably contains debris and as the lady with the umbrella in the video above shows,  there are as many pitfalls for someone wading through a flood as there are for cars.

The various scenarios

  1. The most common scenario is a car in wet weather going into flooded water deeper or faster than expected and being picked up by the current
  2. The second most likely scenario is some form of car accident – which happens to be into water – where you won’t know how deep it is – but it will likely be the edge and so fairly shallow.
  3. The third most likely scenario would be someone driving on a frozen lake or sea who breaks through  (which only applies in areas like Alaska & Canada)
  4. The least common accident (from what I’ve seen) is someone driving into water much deeper than the car.

1. What to do when you drive into or are otherwise subject to flood water

This is likely to happen, either:

  1. Because you intentionally drive across a ford or a known flooded area.
  2. You are driving through “wet conditions” often at night – and get caught.

If you are intentionally crossing a ford or flood, then unless the water is clear, it’s not in flood and you know there’s no danger,  you should wind down a window before you cross. (If you drive fast enough to get water in the window – then you’re driving fast enough and deep enough to flood the engine!)

As soon as you get caught, you should wind down a window (ideally on both sides of the car as it could roll with the open window down).

But this is why I’m writing this article. Because in many instances where there is debris or no obvious path out of the flood,  your best chance of survival may be to stay in … or at least ON the car. WITH AT LEAST ONE WINDOW DOWN.

What tends to happen

The incident tends to go through the following stages:

  1. Many start with a car driving through flood water
  2. The car then stop. (I don’t know whether the driver intentionally stops or the engine stalls)
  3. An incident unfurls with a car in the middle of raging water (this may only be because these are more likely to be filmed)
  4. At some people try to leave the car
  5. The car then starts moving (often with people still inside)
  6. In many instances the cars start “bobbing along” with their fronts down and backs up – bumping into other cars and street furniture. The fortunate ones comes to a stop, the unfortunate ones get into deeper and deeper and faster and faster water.
  7. In other instances (notably fords) the track is raised above the river bed. As such as the car gets pushed over a “shelf” where it usually rolls on its side. And depending on the depth it is either caught on rocks, ends up being dragged down river from rock to rock, or assumes the “feeding duck” position with front down.
  8. Often people struggle out of the flow. Sometimes they are rescued by passers by or emergency services. Often when cars end up floating, it ends in tragedy.

Advice on leaving a car in a flow

In perhaps half a dozen instances where I’ve seen people getting out of cars stuck in flowing water … the car starts moving as they get out. It could be they get out because the car feels like its about to move … but it will certainly have moved because as the people get out there is less weight holding it down and it then starts floating …

And unfortunately, when a car is caught in a large flow big enough to move it, the only doors that open are downstream. And those in this horrific position clearly have problems moving away from the car because the flow speeds up as it goes around the car. So I’ve seen a number of instances, where what appears to be a family group exits a car, they stand in the lee of the car and then (usually with some left in the car) the car starts moving downstream and as it’s usually a causeway across a river – they are all pushed off the causeway. So my advice is as follows:

  1. If the water is shallow enough … open windows on the upstream side (if possible) so as to intentionally flood the car before getting out. This will remove its buoyancy, and stop it floating as you exit.
  2. As people exit, they should climb on the vehicle. This will hold the vehicle down and allow the rest to escape.
  3. If it is safe & you can expect rescue – stay on the car. Because if you end up separated and still in the flood – it’s a lot easier to spot a big car in a flood than one single human.
  4. if the car is moving – then you’ll be pleased to know that humans are better in fast water than most cars – but you’ll improve the odds even more for everyone (particularly children) if you can move as a compact group.

2. The car accident (that happens to land “in water”)

Another reason people end up in water, rather than the road being flooded is that they come off the road and it just so happens they land up in water. But it will probably be dark. You may well be on your side or upside down so disorientated, the car’s possibly bent so the door may jam by itself or some branch is up against it. Quite possibly windows will already be broken, if not you’ll be at the edge where it’s shallow.

But even if you realise you’re in water in your disorientated state you may have no idea how deep the water is.

So unless you know you’re in deep water and even then unless you are pretty cool you’ll first try the door. If it opens then as most people would do in any car accident (because of assumed risk of fires) get everyone out.

It will only be if the door can’t open or you can see you’re in water that you’ll think to open a window. But then don’t delay open one immediately. Because once the water gets to them they stick even if the electrics don’t fail. (which they will).

But don’t panic (yet) if that doesn’t work – you may be in a river or on your side in a puddle or a branch or rock may be against one door or the door may be bent or it may be jammed shut by the current if it’s upstream.

Windows are incredibly difficult to break, so before trying to break windows try to open all the other doors & windows. If nothing opens – unless you have something that will break a window (and many windows appear immune to being broken even by things like axes and hammers) – your best hope is to get into the back (which tends to floats more) and call 911.

As a last resort try to break a side windows

As a last resort try to break a side windows – because smaller windows break easier. I also once read that they are easier to break near the frame – but I’ve not seen anything to confirm that. Your best bet is to use anything hard or metallic with a long “sweep” so that the end hitting the window is going as fast as possible. You could try any tools, stiletto heels, swing a belt hitting with the metal buckle, fill a sock with coins or tie something metallic keys onto tights, bra, plastic bag and swing it round.

Other dubious suggestions for getting out:

  • Wedge your back on one door and with your legs try pushing the top backmost corner of the door/window frame. This will be the weakest part of the door, and there is a small chance you can bend it. You may not bend it enough to get out, but the bending (possibly with a little extra help) might break the glass.
  • There’s a chance any one of the windows (including front) has been badly fitted to create stress and/or has a weak point near the edge. Kicking with your heals, elbows, etc. might just work.


In most hatchbacks you can get into the boot/trunk from inside the car. Some of them even allow the door to be opened from within the car. If so, this is an ideal last resort escape because the boot should be sitting up in the air and be the last part of the car to submerge.

There are also tools, with which you could try to smash a window, but unfortunately in the cars I’ve owned, it would be really difficult to get to the tools (for taking off the tyres) because in most cars they are under a flap which wouldn’t be easily accessible from inside the car.

As a last resort – you may be able to get to the mechanism to open the boot and something like keys might possibly be able to disengage the latch.

 3. Driving into Frozen Lake

I’ve included this mainly because I’ve seen more incidents of this than people driving into deep water. But that may be the nature of online videos.

There is plenty of advice available but the general principle of having a window open and leaving the car ASAP apply – but more-so because the ice may stop the doors opening long before the water gets in.

4. Driving into deep water

Realistic scenarios are that

  1. you’ve unexpectantly driven into deep floodwater (for example a flooded underpass)
  2. You came off the road and drove into a canal
  3. You’re on a slope going into a lake or the sea and the brakes fail.

If you see it happening – most people will try to get out the car through the door. However, once in the water, the water pressure will close the door and there is a danger that as the water starts pushing in on the door, you or your clothing could get caught.

However, even canals can have shallow areas at the side and even peers may be deep at high tide, but the tide goes out. In which case – if you can open a door – it’s much easier to get out this way. But it’s always best to open a front window if the car is floating or moving in any way when in water.

But if you get in deep water, yes once in deep water, you should exit through a window – but in many cars the back windows don’t open far enough for an adult to get out so you will need to exit through the front.

Note, the above video is a little deceptive as the back window is broken. If this were a real incident, the back window catches a big air pocket of air at the back and the car invariably ends up in the “feeding duck” position. This will give a little extra time, but not much and the general advice to open a window ASAP and then get everyone out is right.

Realistically – if it is really deep water (and if the video is realistic in timescale which I’m not certain) – it would be extremely difficult for adults to get out let alone a family with small infants. To get everyone out, people need to be exiting through windows almost immediately.

The best chance of getting everyone out would be if one spouse exits a window as they can’t be any use in the car and there isn’t room for two to work. Hopefully that will give older children the message to get out and the remaining adult can pass out any younger children. But it would be incredibly difficult for parents to exit a car leaving any children behind. So realistically I can’t see a family with young kids all making it out in deep water if the car sinks this fast.

A more sensible plan

I think there are very few incidents where people go immediately into deep water and far more where the car remains afloat for a relatively long time. So I think it is more sensible to plan for the more common and more survivable event of a car in moderately deep water where the front will be sitting on the bottom. What is more, the exit method is the same, but because you have more time you assume that you can get everyone out in a controlled way which is important in the accident I’ve seen where the car lands up in flowing water.

Again doors may be kept shut by water pressure, so the windows need to be opened ASAP, but this time the advice is to open the windows even if you initially land in shallow water that means as soon as the car is stopped in any depth of moving water (above mid wheel height). And you exit as soon as the car feels like it is moving or floating – but now the aim is to get on top of the car to help stop it floating.

Water will pour in, but now that can be a real asset because it sinks the car helping it to stick where it is and stopping it and the passengers being swept down river where the currents are very likely to be stronger and the depths deeper.

Now we assume the back of the car will stay above water for many minutes and possibly indefinitely. However, unlike the “deep water” scenario of a lake or harbour, this time we will assume the water is likely to be moving – so there is a real risk that if exit in a hurry that young children who could be saved, will be swept away with the current. So the aim is to get everyone from within the car, first onto the car and then if possible to safe place.

And whilst this plan if followed would less optimum if you land in deep water – the key message to open the windows is the same and in a rapidly sinking car with almost no time to get out – no one is going to stick to any plan anyway. But they at least have the maximum chance if they start with the windows open.

So, this is a more universal plan in the sense it will be ditched in deep water incidents and it is better fitted to more situations than the “get out as fast as possible” which could be positively harmful for children in fast flow situations.

And call 911/999 AFTER YOU GET OUT
or if you are stuck in the car
(having not opened a window and got out).

Seat belts

I’ve left this subject to last. In theory, if you know you’re going into deep water and you will do so nice and gently – then you should release your seat belt. In reality, water can be as hard as concrete if you crash into it and if you are unfortunate enough to be pushed off a ford, you may well be protected from injuries by having a seat belt. So I cannot foresee any realistic circumstances where there is much to be gained by taking off a seatbelt whilst driving.

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