I measured it tonight just because I was curious.

Same house, same tap, same thermometer as the previous summer reading. It went from ~room temperature to ~60F/16C in a hurry. That's about the temperature of the basement right now.

It then dropped to about 48F/9C as water from the pipe under the street was introduced, and it stayed at that temperature. That'd be great for an incidental cooling loop, except: It's rather cold outside and it will remain cold for months. :)