1. Preparation is Your First Defence
The best way to handle a waterlogged road is to avoid it entirely. Before you even get in the car, check weather alerts and real-time traffic apps for flood warnings or road closures. If a heavy downpour is forecast, ask yourself if the journey is essential.
Delaying your trip by a few hours could save you from immense trouble. Prepare your vehicle by ensuring your tyres have adequate tread, your brakes are in excellent condition, and your wiper blades are not cracked or worn out. In heavy rain, visibility is key, so also check that all your lights—headlights, taillights, and indicators—are working perfectly.
2. Judge the Water Depth Before Entering
Never drive into standing water without first judging its depth. It is notoriously difficult to tell how deep water is just by looking. A good rule of thumb is to avoid entering water that appears to be higher than the bottom of your car's doors or the center of your wheels. Watch other vehicles and pedestrians to get a better sense of the depth. If trucks and SUVs are struggling, your sedan or hatchback stands little chance. Just six inches of water can be enough to cause a loss of control or stall most passenger cars. A foot of water can float many vehicles, and two feet of rushing water can carry away even SUVs and pickups. When in doubt, turn around. It is not worth the risk.
3. Master the Slow and Steady Crawl
If you determine the water is shallow enough to cross and you have no alternative route, the technique is crucial. Engage a low gear (first or second in a manual, 'L' in an automatic) and keep the engine revs high but your speed low and constant. This creates high pressure in the exhaust pipe, preventing water from entering. Aim for a steady speed of around 5-10 km/h. Do not stop or accelerate suddenly. Driving too fast creates a 'bow wave' that can wash water into your engine's air intake, causing catastrophic damage. Stick to the middle of the road, as roads are often built to be highest at the crown, meaning the water will be shallowest there.
4. Beware of Hidden Dangers
Floodwater is often murky and hides serious hazards. The biggest risks are not just the water itself, but what you cannot see beneath it. Waterlogged roads can conceal deep, sharp-edged potholes, dislodged manhole covers, and debris that can puncture a tyre or damage your car's undercarriage. The structural integrity of the road itself might be compromised. Drive with extreme caution and be aware that the surface you are driving on could be washed out. By keeping your speed low, you have a slightly better chance of spotting and reacting to these submerged threats.
5. What to Do if You Get Stuck
If your car stalls in water, do not try to restart the engine. This is the most important rule. Attempting to crank the engine can force water into the cylinders, leading to 'hydrostatic lock,' which can bend pistons and destroy the engine. Turn off the ignition, put on your hazard lights, and assess the situation. If the water level is rising, you need to abandon the vehicle. It may be difficult to open the doors due to external water pressure. If this happens, roll down a window to escape. If the electrics have failed, you may need to break a side window with a heavy object. Your safety is more important than the vehicle. Get to higher ground and call for help.
6. After-Care for Your Vehicle
Even if you make it through a waterlogged patch successfully, your car needs immediate attention. After exiting the water, gently tap your brakes a few times. This helps to dry off the brake pads and discs, ensuring they work effectively when you next need them. Water can get into many mechanical and electrical components, so it's wise to have your car checked by a mechanic. They will inspect the engine oil, transmission fluid, and electrical systems for water contamination, which can lead to long-term rust and failure if not addressed.
