Flood water: how to drive through it safely

Heavy rain showers combined with fallen leaves can create flash floods - and they can spell trouble for drivers. Find out how to drive through patches of localised flooding with our guide...

Flood water - how to drive through it safely

Storm Ciaran is bringing heavy rainfall to much of England, and while the advice in some areas is not to travel, there will still be lots of cars on the roads. In some cases, extended rainfall may lead to localised flooding, and if you're faced with a big patch of water to get through, it can be intimidating. Fortunately, in this story we've got everything you need to know to manage these potentially hazard conditions.

1. Take an alternative route

Never drive through deep, fast-flowing water and don’t drive through flooded roads if you can avoid them. It’s better to add an extra 10-15 minutes to your journey rather than risk your car’s engine and electrics being ruined, or even worse, the vehicle being swept away.

2. Check the water depth

If you have a pair of wellies handy you could wade into the water to see how deep it is (keep a powerful torch in the glovebox for use after dark), or you could park up nearby and watch other vehicles go though it first. Unless you’re driving a high-riding 4x4 or SUV, the maximum depth most experts advise you drive a standard car through is 10cm. Modern cars are generally water-tight so they can start to float when driven through water that’s only 30cm deep.

Flood water - how to drive through it safely

3. Let oncoming vehicles pass

Wait for oncoming vehicles to get through the flood patch before you head into it, especially if they’re larger vehicles or are travelling fast, because they could soak your vehicle and cause it to break down.

4. Drive along the highest point of the road

Most roads dip down at either side, so aim to drive in the middle of the road. That’s another reason to wait for oncoming cars to get out of the way before attempting to cross floodwater.

5. Don’t drive too fast

Drive through flood water slowly – 3-4mph is an adequate speed. If you drive too fast you'll not only create a wave that’ll splash other road users, but you’ll also run the risk of your car’s tyres losing their contact with the road. If this happens, don’t brake, just take your foot off the accelerator and keep the steering wheel straight and wait for the grip to return.

Flood water - how to drive through it safely

6. Don’t stop

Although you should drive slowly, it’s important not to let the car come to a halt while crossing deep water because that could allow water to get into the exhaust pipe, which can cause costly damage. Keep the engine revs up, too; if necessary slip the clutch to do this in a car with a manual gearbox. If you’re driving a car with an automatic gearbox, select the lowest possible held gear and keep your foot on the accelerator.

7. Dry your car’s brakes

Gently press your car’s brakes a few times once you’re clear of the flood – and in a safe place to do so – to dry them off and ensure they respond efficiently.

Flood water - how to drive through it safely

What to do if you break down in floodwater

If the worst happens, and your car gets stuck in deep water stay inside it and phone for help. Don’t get out or open the bonnet or you could worsen the initial damage. Don’t try to restart the engine either as that could push water into it.

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