There was a big fuss a few days back over a Land Rover driver getting stuck in floods on Araneta Avenue. It shocked many people that a supposedly flood-proof car—one driven by an experienced off-roader, no less–could actually get stuck in an urban flood. But that’s life. S*** happens.
Either way, novice or expert, unless you’re on a life-or-death mission, you should never try to brave a serious flood if you can sit it out. When in doubt, don’t.
But let’s say you’re already knee-deep in floodwater and your car has sputtered to halt. What do you do then?
It may be tempting, if the floodwater seems manageable, to restart the engine to drive out of it. Do not do this. I found this out the hard way back when I first started driving and found myself traversing calf-deep floods along A. Bonifacio. I could see how deep the water was, and made a foolhardy choice. It started out manageable, but an errant bow wave from a passing truck killed the car.
"Fine," I thought, "the water is shallow enough that I can restart the engine." Unfortunately, the residual water in the airbox had other ideas, and the car sputtered to a halt again just half a minute after restarting. After pushing it a kilometer to higher ground and calling for a tow, I was hit with a massive repair bill for a hydrolocked engine. An extremely expensive situation that occurs when metal pistons try to compress almost-incompressible water instead of air, which results in broken pistons, bent rods and cracked engine blocks.
How deep is the water? This determines what you can or should do next.
If the water is below the door sills or is just lapping at the wheel hubs, you may pop the hood so you can open the airbox to check for water ingestion. Most modern cars have air intake snorkels behind the grille or just under the hood. But some have air intakes behind the headlight or bumper. It is possible for water to splash up into these and cause stalling even without coming above your knees.
If your air snorkel is far above the water line, the inside of the airbox is dry, and the ignition wires are not compromised, you may try restarting the vehicle and driving to higher ground. Once there, follow our post-flood tips for inspecting your vehicle.
If there is any water in there, or if you are unsure if there is, don’t risk it. While your engine may sometimes stall with just a little bit of water ingestion, there is no way to tell how little or how much water is inside from a cursory visual inspection. Cleaning out a flooded car is much cheaper than cleaning out said car and overhauling a hydrolocked engine.
Don’t attempt to open the doors, as the water pressure pushing on them from outside will seal them shut. And do you really want to let flood water into the car? If you’re lucky and the water doesn't rise any higher, you might not need to wash the carpets out later.
Your car is most likely floating around at this point. Climb out the window, abandon ship, and skip steps 3 and 4. Recovering the car right at this moment is not worth the risk to life and limb it entails.
If you cannot start the car and the water is high or rising, disconnect the battery. This will prevent dangerous electrical shorts if water gets into the electrical connectors or computer boxes. If you know how to remove the computer box and stereo head unit, and there’s time, you can try to save them. Typically, Powertrain Control Modules inside the engine bay are sealed against water intrusion, but those mounted inside the cabin are not. If you’re a handy auto electrician or modder, you’ll know how to remove these. If you don’t, don’t bother. But it is better to err on the side of caution and save yourself. There’s a reason new insurance policies come with Acts of God coverage as standard. If yours doesn’t, maybe you should consider a policy upgrade.
If you’re not alone, or if there are friendly passers-by willing to lend a hand, you can try to get the car to higher ground to dry out and possibly salvage it. If, as mentioned eaerlier, the water is rising fast or is past the windowsills, don’t bother. Exposure, injury and possible leptospirosis infection are much greater threats to your well-being than a flooded car.
If you can’t recover the car, if the current is strong, or if the water is rising, simply evacuate yourself and your passengers to higher ground. Hell, if you are in doubt that you can do any of the other steps given here, do that anyway. As I said, when in doubt, don’t. If you have minimal off-roading or flood driving experience and don’t feel any doubt, then there’s something seriously wrong with you.
Always question whether it’s safe—whether the water is five feet or five inches deep, whether in car or on foot. Being extra cautious could possibly save your life.