Hope you know I was kidding. A cubic centimeter contains 20 drops of water. So how many cubic centimeters of water flooded those towns? Metrics are fun.
The 20 drops of water per cc is simply coincidence and not a matter of design. That number will be different for isopropanol, very hot water, or water with a tiny amount of detergent.
I just want us to go metric every inch of the way /s