Car Leaking Water

If your car is leaking water, it can mean a few different things are happening.  Some water is completely acceptable in some situations.  It really depends on where you’ve found it, and if it’s actually water.


Is it Coolant or Water?

If you are trying to figure out if your car is leaking water, the first thing we need to do is determine if you have coolant or water underneath of the car.  Coolant is sweet smelling and tasting.  It’ll also have a color to it.  Water is tasteless and odorless.

If it is engine coolant, it’ll be coming from different places than water typically will, and will need to be addressed separately.

Car Leaking Water


Leaking Water Causes

Here are the most common reasons that water may leak from your car (not coolant, that is covered below).

Air Conditioning System–  Your cars A/C system leaks water directly underneath the engine bay as it works.  If you have a big puddle of water under your car it may be because it was left running in place for a while.  Fifteen minutes on a hot day can be enough to get a trail to the rear wheels.  This is completely normal and should not be cause for alarm.

Exhaust System–  Your car’s engine creates steam as part of the combustion process.  It is way more noticeable in the winter time when white smoke billows out of your exhaust pipe.  Water can also leak out of the exhaust as this happens.  A little water is completely normal.  A lot of water leaking out of the tail pipe is certainly a cause for concern. 


Some Water Under the Car Might be OK

Your car’s air conditioning system is going to produce water as a product of the cooling process.  This is normal.  It will usually produce moisture just behind the rear tires.  This is harmless water, and is nothing to worry about.


Leaking Cooling System

If it’s coolant on the garage floor, and not leaking water, that’ll be an entirely different set of circumstances causing the leak.

It is possible that your coolant system could be leaking water.  If you, or whoever had the car before you filled the cooling system up with water instead of anti-freeze coolant, it could leak water.  The problem is that water will freeze in the winter time and cause the engine block, heads, freeze plugs, or some other part of the engine to freeze up. 


Common Places Your Cooling System Leaks Water

If your cooling system is leaking water or coolant, here are the most common reasons that it may be doing so:

  • Thermostat Housing–  The thermostat is a small device that acts as a barrier that lets coolant into the engine only when it reaches a certain temperature (usually a bit over 200 degrees).  There is a housing that bolts to the block that holds the thermostat.  It’ll have a radiator hose attached to it.  It is very common to find that the car is leaking water or (hopefully) coolant from this location.  It’ll be toward the front of the vehicle, further up than where the A/C condensation would be.
  • Radiator–  A bad radiator can will cause antifreeze to leak onto your garage floor or driveway.  If you go looking for it, just treat those electric fans like they can run at any time just to be safe.
  • Radiator Hose–  There is a rubber hose that connects the radiator to the thermostat housing, and another one that connects the return from the engine block.  These hoses can leak coolant from them as they dry out and crack.
  • Head Gasket–  The head gasket is designed to fail before permanent damage is done to the block or head when overheating.  This does not mean that the head gasket will only fail if the engine has overheated.  If the head gasket is blown, it could let coolant out of the engine onto the ground.  It could also let coolant into the exhaust, which would manifest itself as white smoke.
  • Cracked Head or Block–  This would be the last thing that you’d want to look at on this list, as it’s far more likely that one of four issues listed above would be causing water to leak from your car.


Conclusion:  Car Leaking Water

Water itself, is often not a problem at all.  If you have a coolant leak, that’s another thing entirely.  Good luck diagnosing the water leak from your car.