Even drivers with local knowledge can be caught out during heavy downpours
Driving in wet conditions can be hazardous and even drivers with local knowledge can be caught out during heavy downpours, as the most modern road surface is still susceptible to standing water.
Standing water creates a potential aquaplaning hazard as well as reducing visibility.
Take it easy through standing water and if the steering does become unresponsive due to the rain, ease off the accelerator and slow down gradually.
Only attempt to drive through flood water if you know it's not too deep and maintain a steady, slow speed to avoid creating a bow wave. The air intake on many cars is low down at the front and just an egg cupful of water in the combustion chamber is enough to wreck an engine.
Water doesn't compress and the piston in effect hits a wall, bending or breaking a con rod. Driving fast - even if the intake's above the water level - could cause water to be ingested.
If you break down in heavy rain don't prop the bonnet open while you wait for the patrol to arrive. The engine will be more difficult to start again if the electrics are all rain-soaked.
Don't enter flood water that is moving or more than 10cm (4 inches) deep.
Allow oncoming traffic to pass first and drive slowly and steadily to avoid creating a bow wave. Test your brakes as soon as you can after leaving the water.
Don't try driving through fast-moving water, such as at a flooded bridge approach – your car could easily be swept away.
Slow down and try to avoid standing water if you can.
As you drive slowly through standing water, use a low gear so the engine rev's are higher; water in the exhaust could otherwise damage the catalytic convertor.
Don’t assume that a ford is always safe to cross just because the road goes into the river on one side and comes out on the other. The depth of the water at a ford, and its flow rate, will change with the weather.
(updated 15 April 2015)