They say the thermoelectric coolers will cool to 30-40 degrees farenheit below ambient room temperature.
This would be more accurate at room temps of 70-100 F. I think it wouldn't do any SUPER freezing job at below 60 F.
http://www.flyanglersonline.com/prorevw/81798prod.html
Would it work to cool the water? Sure it would. I'd get one of those coleman coolers with the removable lid. I'd drill two holes and tap in two spigots, seal it with goopy sealant and fill it with water. It would be great.
If you do go this route...document with pictures every step of the way from pre to post. I'd love to see that as guide and what the pre temps are...and after temps are.