Why is driving in wet conditions so hazardous

Increasingly, extreme weather batters our country, and often our infrastructure and highways are not designed to cope with torrential and monsoon-like downpours. Driving in these conditions is hazardous. Poor weather conditions (e.g. torrential rain or spray shooting from standing water) reduce driving visibility and increase vehicle-stopping distances. There is also an increased risk of Aquaplaning or becoming stranded in deep floodwater.

Road surfaces can quickly become submerged in murky, standing water. You cannot judge how deep puddles are: they could be hiding deep potholes or debris that will damage your car’s suspension and tyres.

In this article we will look at four practical ways to keep yourself, your passengers and your car safe (and dry!), how to drive through floodwater and how to avoid being caught out by flooding:

Preparation – Are you equipped for your journey and weather conditions?

Anticipation – Are your driving behaviours and techniques reactive or proactive?

Application – Do you know what the warning signs and dangers are? How do you drive in floodwater?

Protection – Do you know what to do if your car should get stuck in floodwater or standing water?

Preparation – Are you equipped for your journey and the weather conditions?

  • Before you set off, check the weather forecast and traffic news. If flooding is severe, then consider if you really need to make the journey: only travel if your journey is essential.
  • Every week, carry out a car check – do all the lights work? Are your windscreen wipers smearing or not cleaning the screen? Are the screen wash and coolant levels ok? Do the tyre pressures meet the manufacturers recommendation? If anything needs repairing, replacing (e.g. brakes, windscreen wipers) or topping-up (e.g. fluids), then do it immediately and don’t wait for the next MOT or service.
  • Ensure you have a torch, drinking water, food and warm clothing in the car, in case your car breaks down.

In order to comply with UK law, your car tyres should all have a minimum tread depth of 1.6 mm (if they don’t then your car will fail it’s annual MOT test). The greater the tread depth, the greater the contact and ‘grip’ each tyre has with the road. But, why is this important? Well, if your tyres are not ‘gripping’ to the road, they won’t respond to your driving style and you will lose control of steering.

In wet conditions, the tread depth is vital, as a deeper tread will remove a greater volume of standing water from beneath the tyre, increasing ‘grip’ to the road. Aquaplaning occurs when your tyres lose ‘grip’ with the road – there is a layer of water between the tyre and the road.

Anticipation – Are your driving behaviours and techniques reactive or proactive?

Whether driving in dry or wet conditions, most drivers are reactive – by the time they spot a problem or realise something has gone wrong it is too late! Many accidents are caused by a lack of concentration, not allowing enough of a stopping distance or by a driver not paying attention to their surroundings and other road users. Accelerating and braking hard are dangerous driving behaviours – even more so in wet conditions.

Proactive driving is recommended in all driving conditions:

  • Speed limits are set for a reason – so respect them;
  • Look further ahead than the vehicle in front of you. Notice junctions, potential hazards and road signs ahead of your car, for as far as you can see.
  • Expect the unexpected;
  • Adapt your driving style to the road conditions and weather. For example, a country road may have a herd of sheep crossing the highway around the corner;
  • In wet conditions, you will take longer to stop and your car may Aquaplane.

Application – Do you know what the warning signs and dangers are? How do you drive in floodwater?

There are several situations, where you may encounter floodwater and surface standing water. But how should you adapt your driving style and behaviour for each situation?

Heavy rain:

  • The Highway Code states that drivers’ must use headlights if visibility is reduced below 100 metres (328 feet).
  • If you turn on your fog lights, then you must switch them off if the visibility improves.
  • Stopping distances increase so double the distance you would allow for stopping in dry conditions. No tailgating! Mirror, signal and manoeuvre – plan these actions well in advance.
  • If steering becomes unresponsive, reduce your speed by taking your foot off the accelerator, so you gently decelerate.

How to drive in floodwater:

Where possible, avoid driving through standing water and find an alternative route. If you can see that the floodwater is moving then do not drive into it. Likewise, do not drive into floodwater that is deeper than 10cm (4 inches deep): your engine can be ruined if water gets into the internal combustion chambers engine. by just a shot glass (25 millimlitres) of water a shot glass of water in an engine’s combustion chamber will wreck an engine. Thirty centimetres (1 foot) of flowing water could lift a family car and carry it downstream.

If this is not possible, here are some useful tips and information on how to drive in floodwater:

  1. Show consideration for other road users, including pedestrians and cyclists, who can be soaked by water thrown from standing water onto pavements.
  2. You want to avoid creating a bow wave, which can rush into the internal workings of your engine. Let the oncoming traffic drive through the flood first – you can also see how deep the water is.
  3. Drive into the floodwater in a low gear, so the engine revs are higher and stay in a low gear, moving forward steadily. If water gets into the exhaust system, it will damage your car’s catalytic convertor.
  4. If you lose steering control and the car starts to Aquaplane you need to decelerate so hold the steering wheel tightly and lift your foot off the accelerator pedal, until the tyres regain grip.
  5. Once you are out of the floodwater, and it is safe to do so, test that your brakes are working.


  • Where possible, find an alternative route – do not cross fords in flood.
  • Even locals can misjudge the depth and flow rate of a ford – especially as the ford will react to the weather conditions, and water levels and flow rate will continue to rise after the rainfall has stopped.
  • Follow the advice given above.

Protection – Do you know what to do if your car should get stuck in floodwater?

If you break down in standing water, and it is safe to do so, leave your car and find a safe place to call the recovery services. If it is raining, keep the bonnet closed to stop the rain from soaking the electrical engine components.

So in this article, we’ve looked at how to drive in floodwater and how to keep yourself, your passengers and your car safe.

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