How to drive in flood water

It’s easy to be blasé when dealing with flood water, but you need to be incredibly careful as such conditions can catch you out big time. Not only can a swollen river carry your car away, but if water gets into your car’s electrics it can be written off by the huge cost of putting things right.

What’s more likely to wreck your car though, is water being sucked up into the engine. Your engine needs air to breathe; this gets in via an air intake. Different cars have this air intake positioned in different places, but it’ll be at the front of the car; the critical thing is what height it’s set at. 

The golden rule is that if you’re in doubt and there’s an alternative route, take it

Think of your car’s engine as being like your body; your lungs need air to breathe, but if you’re submerged in water, you’ll suck in water and drown. The same thing can happen to your car.

The golden rule is that if you’re in doubt and there’s an alternative route, take it. if the water if more than 30cm deep you’re in danger of being swept away, unless you’re lucky enough to be driving a hefty 4x4.

Here, with the help of the Institute of Advanced Motorists (IAM), are the things you need to do to stay alive next time you have to drive in flood water: 

  • Drive on the highest section of the road and don't set off if a vehicle is approaching you.

  • Leave time and space to avoid swamping other cars and pedestrians.

  • If you can’t see where you’ll exit the water, such as when approaching flooding on a bend, think twice about driving into it.

  • Once in the water, keep the revs up, stay in a low gear and slip the clutch if necessary to keep your speed down; you don’t want to create a bow wave in front of your car, by driving too fast. Maintaining revs helps prevent the water from travelling up the exhaust pipe and into the engine.

  • If you have to stop in the water, keep the engine revs up. Let the revs drop or stall the engine and you’ll probably be stranded.

  • Once you're out of the water, dry the brakes before you need them. Check there’s nobody behind, then apply the brake as you drive along for a few seconds.


* Also check out our page on how to drive in rain.