• Always assess the situation before driving through a flooded road
  • Even 4x4s can be at risk in flooded areas
  • The danger isn’t over as soon as you get out of the water

Although modern cars are relatively safe to drive through standing water, it doesn’t mean that floods should be underestimated: they are still dangerous for cars and their drivers.

Not only can floodwater cause irreparable damage to a car’s interior and electrical system, there is a risk of it getting into the engine and making it seize.

In addition, fast-moving water can put drivers at risk of endangering themselves – in some conditions as little as four inches can be enough to sweep a vehicle away. 

1. A different route

Before trying to drive through a flooded area always check to see if there is a different route you can take – only attempt to ford a flooded road as a last resort.

2. Stop and assess

You can never be sure of the depth of water or the state of the road underneath without taking a close look. If you are crossing at a ford there may be a water depth gauge at the side of the road, allowing you to assess the stream’s level.

Also check the area for other hazards such as floating debris or downed power lines, where the electric current could be conducted by water.

3. Check the depth

The general rule is that you should not try and ford standing water that is more than six-inches deep – so if it comes over your wellington boots then it’s a no-go.

If it is moving, the maximum depth is even less: any more than four inches of moving water can be enough to sweep a car away into deeper flood water.

4. Take care when passing other vehicles

Avoid following or crossing against other drivers that could cause you to stray off your intended trajectory. Large vehicles are especially hazardous as they can create waves that will push the water higher than expected.

5. Aim for the highest part of the road

Usually the highest part of the road will be in the middle (called the crown), as most roads are designed to let water drain off the sides. Make sure you keep your eyes peeled for hidden dips (such as potholes, gullies and trenches) where the water could suddenly get deeper.

6. Stay in first gear to keep your speed down

Richard Price, chairman of Sussex 4x4 Response, an organisation that provides assistance to the emergency services and local authorities in adverse weather conditions, recommends that you enter the water at 1-2mph.

“Hitting the water at speed could cause the car to aquaplane, which is when the wheels lose their traction and the driver loses control,” he explains.

7. Keep your car revving

Once in the water, try and keep the car’s revs up, this will avoid water being sucked back into the exhaust.

“You can accelerate up to 4-5mph as this will create a small wave, protecting your car’s engine from the worst of the water,” says Richard Price.

If you drive a manual and you find that keeping the revs high is making you go too fast, try slipping the clutch.

8. What to do if you stall

The most important thing to avoid while clearing a flooded section of road is stalling. If this happens it is important to try and start your car straight away, as the longer you wait, the further the water will be creeping up your exhaust system.

9. Dry your brakes

Normally if you follow steps one to eight you should make it out of the other side of the flood, but that doesn’t mean that you are in the clear yet.

It is important to remember that your brakes will be wet and in order for them to work properly you need to dry them.

For the next few miles, drive slowly and regularly apply the brakes lightly to heat them up and help the water to evaporate.

10. What to do if your car stops

If your car does stop in the flood, you should climb out and lock the doors before wading to terra firma.

It may seem drastic to abandon a stranded vehicle, but in these situations personal safety is the most important thing.

Modern vehicles are surprisingly resilient when it comes to water damage and can withstand more than you would expect, but for piece of mind consult your car insurance provider about their breakdown cover.