"How about using the toilet tank? In the US all accept the most expensive low water toilets have a large enough tank. This would eliminate the cooler, the water would circulate avoiding unwanted mold/bacteria, each flush would bring in cool water, and the pump and cold packs would reduce water usage."
"So, would you want me to make a looped system using a toilet tank as a source of constantly cool water?"
"I freaking love this idea."
"It's entirely doable, if you're willing to have a decent length of tubing running through your house. It might be a great way to cool a bedroom thats near a bathroom though... Great Green idea!"
Home Made Air Conditioner at Instructables.