You misunderstand completely. Anything below ambient air temperature, even hoses containing chilled water, will attract condensation on its outside-facing surface from moisture in the surrounding air. This has nothing to do with the substance within the tubes, other than the temperature in said substance. In other words, if any part of this assembly dips below ambient temperatures, water will condense there. If that place is placed so that this water drips or runs onto powered components - uh oh.
If that setup cools the radiator or coolant to anything below ambient, it will still condensate along the radiator-to-CPU tube and on the cool side of the CPU block. Also, that setup is purposely making the peltier system inefficient by drawing hot air from the hot side over to the cool side. In other words: purposefully done bad design. Yeesh. It would be far better to insulate any part of the cold side not contacting water and regulate the peltier through a high-frequency thermal probe and regulator setup. At least then it wouldn't need its own waste heat to avoid condensation. Then again, the sketched setup could provide a pleasant,
cool warm mist for the user if placed in a suitable location. I guess that's something
Seriously, though: the heat output of a peltier is always higher than its cooling effect (laws of thermodynamics and all that). As such, a setup like the one you've sketched up will, except for at points where the cool side is directly contacting the water pipes,
effectively warm the water, not cool it. Unless the warm side of the peltier is cooled entirely separately from the rest of the system. If the waste heat from the warm side is drawn into the radiator with any efficiency, it will cancel out any cooling effect of the cool side.