If we see an iceberg, I will say, yes and 9/10 of it is underwater!!! How can I say this? As a kid we filled the icecube trays and put them in the freezer, did you?? We learned to fill them not quite full, because the ice expands, and as an adult, I looked this up. when water freezes, the ice is fully 10% more volume. Maybe things change under high pressure, but the curves say than the freezing can exert 20,000 pounds per square inch, yesssssss. We’ve all frozen metal plumbing at some point… to our dismay. Given these numbers, we don’t have a chance. DRAIN IT !!! Last November, I blew hard into the hose fitting for my 3 roof sprinklers, feeling I had cleared them. I had not, damn. This autumn, I will go up on the roof, and lift the 1/2″ copper lines making sure they are drained. WIth icebergs if you are a ship captain, you had better know this, and use your imagination correctly, steering clear with wide berth.