I brewed a vienna lager today and with it being late summer I knew our tap water wouldn’t cool the wort far enough. Here in Milwaukee we’re fortunate to have cool tap water all year but it does get up to 55-60 in the summer which doesn’t work well for getting the wort down to 50 or 55.
Using my cleaned-out mash tun as a ice water tub and a pond pump I was able to chill the wort down to 59. It was moving really slowly at this point so I figured I’d let the freezer take it the rest of the way to 50. The temperature of the ice water was about 42 so there was cooling potential left but I got impatient. I used a ton of ice; 5 half-gallon milk jugs, 6 ice cube trays, and a 4-5 cold packs. I cut off the plastic from the milk jugs and chunked up the ice blocks with an awl in order to get more cooling surface area. Tap water was used to cool the wort down to 80 and then I switched over to ice water. I recirculated the “warm” water right away but I suppose refilling the tun w/ tap water would have kept the ice water cooler because it’s at 55 instead of 60-80 degrees.