Flood-water

In many countries, particularly in the tropics, rainstorms can quickly turn roads into rivers and rivers into lakes.  The depth of water in low-lying areas can increase very rapidly and poor drainage often leads to flooding. At times like this driving should be avoided where possible.

• If you have to drive during or after very heavy rain, choose your route carefully to avoid the low-lying areas where you know that water collects.  If you find yourself driving through water that is 10cm / 4 inches deep, drive slowly through the stretch of water and then apply your brakes gently as you leave the flooded area.  This is not so necessary with modern disc brake systems, but nevertheless helps to restore their efficiency.
• If you are obliged to drive through water that is 20cm / 8 inches deep, first wait until the car in front of you has reached the other side of the water.  Then engage 1st (or low) gear before entering the water and maintain a steady slow pace until you reach the other side.  During the "crossing" you should try to maintain the engine revs at a high level, if necessary by riding the clutch.  If there is not a sufficient level of exhaust gases to prevent water from entering the exhaust / silencer / muffler, the car will stall and it will be virtually impossible to restart.  This would not be so easy with an automatic gearbox - but using the lowest gear and maintaining a steady pace should have a similar effect.  Also try to avoid going too fast as this could result in too much water rushing into the engine compartment.  If water finds its way into your air intake it will seriously damage, or ruin your engine.
• If the water is over 20cm/8" deep you should avoid driving through the water unless your vehicle is equipped to do so.  The only vehicles in this category are normally 4x4s with a higher ground clearance and whose air intakes are higher than conventional cars.  Even 4x4 owners should take care that the appropriate plugs are in place before "wading" in water over the axles.  If as a 4x4 owner you are regularly going to be using your vehicle in water over 20cm deep it would be as well to order a raised air intake (snorkel) as a fitted option.
• Finally, if you don't know how deep the "stream" is, don't take a chance; take your shoes off and walk across to the other side of the water and back. Do this twice to ensure there are no submerged logs, boulders or other debris which could impede your progress. Your owner's handbook will tell you about the maximum depth your vehicle can cross. As a rule a diesel engined 4x4 will perform better in these circumstances than a petrol / gasoline and you should make the crossing in low range 1st gear (4x4) with as many diffs locked as possible

The photos below show the condition of many roads up-country in the rainy season and also what can happen if you don't walk across to check the depth of the stream.  An expensive lesson !

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