petrol + air ---> nitrogen + CO2 + water
Water coming out of your exhaust is normal until the car heats up enough that its steam that comes out and you don't see it.
Even if its not water from combustion, if its water leaking into the cylinder from a failed head gasket, once the car warms up and the exhaust gets up to its operating temperature it should be turning into steam and coming out as that, not as water.