The water you exhale is just the amount of water that happens to evaporate in your respiratory tract/lungs. The water you urinate is whatever "extra" water is l

The water you exhale is just the amount of water that happens to evaporate in your respiratory tract/lungs. The water you urinate is whatever "extra" water is left over (based on a bunch of factors like blood pressure, how much stuff is dissolved in you blood, etc). The water that leaves via your lungs and the water that leaves via your kidneys all had to get there via your blood. There's no distinction made based on the "source" of that water.