Frozen Water Pipes

We hit -25 degrees wind chill today, and with that temperature came the unexpected "frozen pipes" call from a tenant. Some days, Mother Nature can be such a bad person...

HZG owns several up and down two units. In this particular 2-family, it was the upper unit that had the pipes freeze in the sink area (not the bathroom). What could be causing this headache? This unit sits into a hillside. The main water line should (I repeat, should) be 4' into the ground where it enters so as not to freeze. With this being the case, Fix-It Guy and I believe that it's not.

The bad part of this is that there is literally nothing we can do short of ripping up drywall and installing heat tape. The tenant has passed on this idea, for the mess won't be worth the inconvenience. As the temperature warms up, the pipe will thaw and water will flow...that's the theory, anyway.

You can be the best landlord / retro-fitter and it may not matter when Momma Nature comes to town. There is only so much you can prevent against.