My water is about 70 now. Have noticed it creep up a bit, was in the high 60s but not enough to worry about it yet. I have been making sure to read every CHILLER thread. If I had the space, I would build my res. inside of a Chest Freezer and use an analog controller to control temps like I do for my homemade kegerator. Have seen guys take apart fridges and use the coils and freezer plate INSIDE the res and that just seems backwards.
I have to control temps in my brewing process as the beer needs to ferment in the low to mid 60s. I only have to deal with high temps for 2 months out of the year.