Stopping the water
The fixture stop, the main shutoff on the house side or the curb valve at the Austin Water meter box, whichever will actually isolate the leak with the least disruption.
A split supply line puts out water continuously until something closes the valve. Shut the water off at the meter box by the curb if you can reach it safely, then call Austin Emergency Plumbing Pros to be connected with an independent plumber.
Austin lost thousands of supply lines during the February 2021 freeze, and most of them failed in the same places: attic runs above insulation, pipes in an uninsulated garage wall and hose bibbs left uncovered. Those are the first places worth checking when a pipe lets go in cold weather.

Not every burst needs all of this. The water is stopped first, then the failed section is found, and only then is a repair quoted.
The fixture stop, the main shutoff on the house side or the curb valve at the Austin Water meter box, whichever will actually isolate the leak with the least disruption.
A pinhole is a symptom, not the whole story. The length of pipe around the split is inspected, because a line that froze once usually froze along its whole exposed run.
After a freeze the water heater connections, hose bibbs and any exposed lines get looked at before the water is turned back on at full pressure.
A short accessible repair is a different job from a line buried in a wall, a ceiling or a slab. The quote should say which pipe is being replaced, how much of it, how the wall or ceiling will be left, and what still needs checking once pressure is restored.
If the meter keeps moving after the visible break is repaired, the next step is leak detection; when the trail leads under the floor it becomes slab leak repair. A freeze that split a pipe often damages the water heater connections too, so it is worth reading water heater repair versus replacement before approving a new unit.
Service covers Austin and the surrounding towns, including Round Rock; the full list is on the service areas page.
Access is usually the biggest factor: an exposed pipe in a garage is a short job, while the same split inside a ceiling means opening and repairing the structure around it. Pipe material and the length of line being replaced matter too. Ask the independent plumber for the figure after seeing the break, not over the phone.
Most homes here are shut off at the meter box set in the ground near the curb, usually under a rectangular lid. Many houses also have a valve where the line enters the building, often near a hose bibb. If the lid is stuck or the valve will not turn, leave it and say so when you call.
Once the main is closed, nothing runs. If only one fixture line is isolated, the rest of the house can be used, but avoid running the water heater dry and stay away from standing water near outlets or appliances. Tell Austin Emergency Plumbing Pros what you have already closed.
Often it does. A line that froze or corroded in one spot has usually been exposed to the same conditions along its whole length. Ask the plumber to look at the rest of that run, and to quote anything further separately so you decide.
Call and say where the water is coming from and what you have already shut off.