Obviously you have never had to deal with 60+ years old outside galvanized 3/4 inch piping. Call me when you get a clue. Even if your plumbing is pristine "copper" or PVC, best bet is to cover outdoor faucets/spigots and drip water on the inside to allow pressure a place to release to as outside pipes begin to freeze. How long have you lived in the Hill Country?

Your pipes are not going to burst. Especially if they are copper. It will take extended and below-zero temperatures to freeze water pipes to the point they will exceed the pressure ratings of copper and even some PVC rated for pressurized lines. Put some insulation caps on the faucet ends and sleep easy. Its not going to be that cold unless you are far north of Austin.