When I start my car in the morning I let it idle for a while and then always find 2 puddles of (water?) on the floor. I noticed a couple of days ago that it's coming from the exhausts in the back. After like 5 minutes it stops leaking. I guess it's just condensation or do I have a problem?

 

condensation

 

Drain hole in the mufflers allow condensation to escape and not build up in the muffler can-helps extend the life of the muffler.

 

The average composition of gasoline is C8H18. When burned in air, you get:
C8H18 + (12.5)O2 + (12.5)(3.76)N2 -> (8)(CO2) + (9)(H2O) + (12.5)(3.76)N2
C8H18 + (12.5)O2 + (47)N2 -> (8)(CO2) + (9)(H2O) + (47)N2
where:
C = Carbon
H = Hydrogen
O = Oxygen
N = Nitrogen
In Air, there are 3.76 molecules of Nitrogen for every molecule of Oxygen.
So, the products of combustion are Carbon Dioxide, Water, and free Nitrogen. The Water in the tailpipe condenses on the cold surfaces and drips on the ground.
After everything is hot, the Water stays in a vaporous condition.
Isn't that nice?