29 November 2021
SLIPPERY WHEN WET: How to drive through floods like a pro

Our comprehensive guide to dealing with floods on the roads, aka “ponding” – from the risks involved to best methods of actually driving through them.

Alright, so you’ve taken all the steps we suggested in our previous wet weather driving article and are now as prepared as ever for a sodden journey. But as we’re all too familiar with in Singapore, sometimes the rain can be so intense that the drains are overwhelmed with water, and thus flash floods can pop up in an instant.  

So what’s a driver to do when the road ahead looks more like they need a boat than a car? Here are our pro tips:

Avoid it if you can

As the saying goes, prevention is better than cure, and that holds true here as well. The best way to keep your car from being damaged by floodwaters is to not drive through them at all!

These drivers are playing it safe.

Not only do you run the risk of your engine cutting out, but even if you make it out the other side, driving through deep water can have lasting effects, like corrosion on the mechanicals or underneath the body; contaminated fluids; intermittent electronic issues if the wiring gets wet; or a damp and musty interior if water gets in. 

Thankfully, unlike other countries where flash floods can occur because of an overflowing river, in Singapore the underlying causes are almost always an inundated drainage system, so there are rarely any serious safety risks to floods here (fun fact, 15cm of moving water is enough to sweep a person off their feet; just 30cm is enough to move an entire car).

Listen out for traffic updates on your car radio, monitor the traffic situation on Google Maps or Waze, and check the NEA’s myENV app or PUB’s new Telegram channel for up-to-date flood warnings. Armed with such information, hopefully you’ll be able to alter your routes or modify your plans to avoid going into flood zones entirely. Much better to be stuck in traffic than stuck in water!

If you’re already in an area where the waters start rising though, or going through a flood is otherwise unavoidable, these are some things you need to note.

Know your car well

Being familiar with the ins and outs of your car has many benefits in general, not just when dealing with floods. But in this particular situation, it’s especially crucial to know where your air intake is, because that’s the easiest way for water to get into your engine. And once that happens, it’s game over. 

The intake channels on a Mini Countryman.

Pop the bonnet and have a look at where the intake tract originates – in most modern cars, it’ll be a plastic duct attached to the radiator grille, leading to a large black box (which houses the engine air filter), and then into the engine itself. But in some cases, that intake duct might route to the lower portion of the bumper.

Analyse the conditions

Armed with that knowledge, you can then make a better assessment of the situations you can and can’t attempt. Try your best to estimate the depth of the flooded area based on the road furniture or the cars around you. 

As long as the water doesn’t rise up above kerb height, or halfway up a car’s wheels or up to its sills, then it’ll generally be ok to attempt driving through. But if you can’t see the road surface or lane markings through the water, that’s usually a good indicator not to try. As a general rule, if you have any doubt at all, then it’s better to be safe than sorry.

Driving through the flood

If you’ve assessed that the water levels are low enough to make an attempt, try to stay in the middle of the road. Roads are usually crowned, which means that the middle is slightly higher than the sides where the kerbs are, to facilitate water drainage. Unless the road is undulating, the crown is where the water level will be at its shallowest.

Unless your car has a snorkel and looks like either of these…

… don’t even think about charging through the water full speed ahead. In addition to the obvious, which is water splashing too high, getting into your engine and knocking it out, you might also do physical damage to your car. Water may be a liquid, but it actually behaves momentarily like a solid if enough force is involved, and too much speed can easily break plastic clips or dislodge body panels.

Instead, select a low gear (1st in a manual transmission; “L” or “S” in an automatic/DCT/CVT, or 1st as well if it has a manual selection function), enter the water at a moderate speed, and “push” it aside with the nose of your car. Wait till a bow wave has formed in front and stay just behind it. The height of the water immediately behind the wave is slightly lower, which will improve your chances of making it through. 

Do not get greedy with the accelerator and overtake the wave, as the water level will probably build up above your intake. Yet, it’s also important to keep your momentum up, so don’t completely get off the throttle until you’re out of the water up, even if the wheels are spinning. 

This video of Rufford Ford in Nottinghanshire, England, shows textbook examples of what you should and shouldn’t do:

Despite driving an SUV from the best off-road vehicle manufacturer in the world, the driver of the red Range Rover Velar at the start of the video still gets defeated by the water, especially with so much of it splashing over his bonnet. Contrast that to the white VW Scirocco driver at 3:03, who slows slightly after entering the crossing, always ensuring he can see the bow wave in front of, and makes it out despite driving a fairly low car.

If you survived the watery onslaught, congrats! Just make sure you do a couple of hard stops at low speed to dry the brake discs and pads. You don’t want wet brakes to prevent you from stopping at higher speeds.

Worst case scenario

If you got it all wrong and your car did die, don’t panic. Your best solution is to turn on your hazard lights, sit inside or get out and seek shelter (depending on the situation), and wait for help to arrive. 

Whatever you do, don’t try to restart the engine. Unlike the air/fuel mixture that gets sprayed into your cylinders, water doesn’t compress, so when the engine turns over and tries to force the pistons up during its compression stroke, it’ll simply stop in its tracks at best, or at worst, bend or break something within the bowels of your engine, like a connecting rod. 

If the engine stopped purely because of water entering the cylinders, it can still be flushed out with minimal long-term effects. But if attempting to fire up the engine caused something else to break, you’re looking at replacing your entire motor.

AutoApp can prepare your car for the year-end monsoon with our wet-weather packages. Download the app here or in case of any emergency, contact our hotline at 91 028 028 and we’ll be happy to advise accordingly.