[tgsovlerkhgsel]

Even if your pipes didn't freeze, the upstream pipes could have frozen, or enough of your neighbors' pipes could have frozen, burst, and gotten thawed again, allowing water to flow freely out of the system.

[tharkun__]

Funny you mention that. Quebec is used to cold weather.

Aging infrastructure. There's not a single winter that you don't hear about water main breaks ;) Seen a few parking lot lakes myself over the years.