Keep in mind that attempts to regulate temp with colder water are only temporary.
If you add cold water, then it's going to absorb more heat until you get to an equilibrium temp. With charcoal, you'll have to give the coals more air to keep your temp, but once the water comes to an equilibrium temp, your cooker temp will overshoot and you'll have to choke back the coals to keep the temp down - and choking coals is never good.
If you add boiling water, you'll start at near equilibrium, your vent settings won't be off track, and it will be much easier to keep the cooker temp steady.
Regulating the temp in your cooker should be done primarily at the heat source, not with water.
If over-condensation is an issue, just pre-heat the smoker dry for a while, then add the boiling water.