Fording through floods

How to drive through flooded roads

When you plunge your car into the water, do it slow and steadily.

When you plunge your car into the water, do it slow and steadily.

The time of year has come when bikinis and board shorts are put back in storage to give way to umbrellas and jackets. Yes, the rainy and stormy season is here again and with it, floods.

Rising water is an ever present problem in a country that lies directly in the line of storms from the Pacific, and being in a highly-urbanized and extremely congested area like Manila doesn’t help either. Sewers and drainage pipes easily get clogged so flooding in the 16 cities and lone municipality that makes up Metro Manila is quite common.

Given the reality of urban motoring, we will all at some point have to find a way to ford through flood waters to get to where ever it is we are going. To better help us along, here is a short and simplified guide on to how drive through a flooded area if there is no other way but through it.

The importance of maintenance
Let us make this clear: do not even think of attempting a tricky flood crossing if your vehicle is not in good working order. This doesn’t mean that so long as your vehicle works and starts, it’s okay. Crossing a flood is very tough on a vehicle’s powertrain and is particularly risky on the electrical system for the obvious reasons. If your vehicle has a history of stalling or have worn out components like the clutch (i.e. sliding), don’t try crossing water.

Know your vehicle
There are two numbers you should know about your own vehicle: ground clearance and wading depth. The ground clearance is typically defined as the distance between lowest point on the underside of the vehicle to the road while wading (or fording). Meanwhile, depth is the deepest water level that a vehicle can take on. Both of these numbers are sometimes printed by manufacturers on the brochure, so take note of them. Typically they’re indicated in millimeters, so convert them to inches if that’s easier for you.

A flood that is just as deep or shallower than the ground clearance poses no problem, even for the average family sedan. But when the water level approaches the maximum wading depth, things become tricky and risky. The general rule is to know at what height the vulnerable vehicle systems are, like the electronics (i.e. ECU, distributor) and the intake tube or air filter. Below such sensitive systems is the maximum wading depth. Every engine is different, but should your engine suck in water through the filter or the ECU gets submerged, it’s game over.

Gather intel on the water and the road underneath
Floods are, quite simply, obstacles to be dealt with and any strategy to get past it will depend on how much you know about them. First, you need to observe if other vehicles are actually going through; if a regular sedan is going through, it shouldn’t be a problem for most cars. But if you see SUVs and trucks parked on the side trying to wait it out, it might be best to park there as well.

Nevertheless, if you do need to wade through, you need to know how deep the water is. Use the objects around that you can or can’t see to give you an idea of the depth. If you can’t see the curb or sidewalk anymore, the water is at least six inches deep. If you can’t see a fire hydrant, then it’s too deep for most vehicles. Don’t be shy to ask the locals about how deep it is, but at the end of the day, it’s your judgment that counts.

As a general guide: 6-8 inches of water is passable for most sedans, 8-16 inches is doable for typical crossovers while 16-30 inches is more in the realm of larger, taller SUVs and pick-ups.

If you’re familiar with the road, take note of features on it that you can use to increase your chances of getting through like putting your car up on the sidewalks (if unoccupied, of course) and perhaps even a crown on the centerline of the road to give an extra inch or two of height. Also take note if there is a water current and judge whether it is safe enough for you to pass. This information will allow you to think of the safest way through.

When you do decide that it is safe enough to risk driving through a flood, there are some important but simple techniques to keep in mind.

Flood Driving 101
First, you should time your crossing to when there is no oncoming traffic, as they could generate a wave that would be dangerous for oncoming cars. You also have to pick a gear that will prevent you from stalling mid way through the flood; generally it’s second gear whether you’re driving an automatic or a manual.

When you do take the plunge into the water, do it slow and steadily all throughout, with your foot applying steady pressure on the accelerator to maintain an ideal speed; usually around 10-15 kilometers per hour. If the water is deep enough, your vehicle’s bumper will create a bow wave and this is what you must follow: Never overtake that wave or let it go over the hood, as right behind it will be the ideal place for your engine as the water is shallower (the trough) much like in an actual wave on the beach.

Whatever you do, do not stop until your vehicle clears the flood. Chances are water will slosh around the underside of your vehicle; it’s a disconcerting sensation, so it’s vital that you do not panic and lift off the throttle. When you do clear the flood and get back on un-flooded ground, do not get on the gas and speed off right away. Go down and check your vehicle and engine bay for any potential damage or debris that could have been trapped inside. Also, this will be the time for you to dry off the brakes, as floodwater will act as a natural lubricant for one of a vehicle’s most important systems. Do not forget to take your vehicle for a check-up and service after making a successful flood crossing.

If you have noticed, there really is no guaranteed one-size-fits-all way to get through a tricky flood. Crossing deep water isn’t an exact science because there are too many factors to consider. So this quick guide is all about reducing the risk of getting stuck and maximizing the chances of forging a way through. And getting home safely.


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