How fast would a bucket of water cool down?

Suppose i have a 10 litre bucket (~340 fl.ounces) of tap water at 15°C/59°F temperature out of the tap. I place the bucket outside at 0°C/32°F ambient temperature. How long would i have to wait until the water temperature in the bucket is at 5°C/41°F?

I know it’s a differential equation of sorts, but it bothers me that i can’t solve this really mundane question.. Any ideas on the math?

Side information:

By the way, it’s not a homework question. I’m brewing my own beer, and chilling the brew quickly before fermentation is the hard part (speed is key lest the brew gets infected), and i wonder how long before i start brewing i have to tap the coolant water.

PS. You have no idea how hard it is to chill a 20L bucket of 60°C beer to 20°C quickly. I’ve tried submerging, hosing with tap water, blowing on it, ice cubes, everything.. You need volumes of coolant! ;)