It’s not the depth of the waterlines. It takes weeks and weeks to get the frost line low enough to hit the standard line depth. Longer than MN because geology and shit.
it’s the pipes in the walls and such freeze, the ice spits the pipes, shit thaws out and all hell breaks loose.
We had a townhouse with a garage attached with a 10 foot breezeway. Codes required a sprinkler system, but the builder apparently forgot to insulate the one point in that breezeway.
One day in February (I think it was the year of Snowmageddon), my wife drives up to the garage and sees water pouring out from the door. The pipe going to the sprinkler head froze, broke and was fine until it warmed up. I think USAA paid $20k for the repair.
When we built the new house I made sure that every water pipe was over insulated.