Stopping the water
Isolating the failed section at the nearest valve, or at the main, so the rest of the property can be used while the repair is planned.
A split pipe puts water into a house faster than most people expect. Shut the main valve if you can reach it safely, then call Plano 24 Hour Plumber to be connected with an independent plumber who can find the break, stop it and repair the line.
While you wait, turn the water off at the meter box near the curb, keep people away from standing water near outlets and appliances, and move what you can off wet floors. Do not go into an attic where water is running near wiring, and do not try to cut into a pressurized line.

Not every call needs all of this. Ask the provider to separate the repair that stops the leak from any additional work you may want to think about afterwards.
Isolating the failed section at the nearest valve, or at the main, so the rest of the property can be used while the repair is planned.
One visible split can sit next to another one you cannot see. Ask for the run to be checked on both sides of the break, especially after a freeze.
Cutting out the damaged section and joining in new pipe with fittings that suit the existing material, whether that is copper, galvanized steel or PEX.
Water back on, the joint watched under pressure, and the area left dry before anyone calls the job finished.
Pipes in attics, exterior walls and unheated spaces are the ones that fail in a freeze. Ask which runs are exposed.
Ask for a plain description of what failed and what was replaced, so you have something factual to pass on if you are making a claim.
A single clean break in an accessible run is usually a short repair. It gets more involved when the pipe is behind tile, inside a slab or in a section that has already been patched several times. In those cases the useful question is whether to keep repairing that run or replace a length of it, and the plumber should say which one they would do and why.
The February 2021 freeze showed how much of the local damage happens in attics and exterior walls rather than underground. If your break is under the foundation instead, see slab leak repair. If water is appearing but you cannot see where it is coming from, start with leak detection. When the burst line feeds a water heater that is also past its best, the repair versus replacement comparison is worth reading before you decide.
Referrals are available in Plano and nearby towns including Richardson and Allen. The full list is on the service areas page, and this guide walks through the first ten minutes.
In most homes here it is at the meter box near the curb, under a rectangular lid at the front of the property. Inside the lid there is a valve you can turn with a meter key or a wrench. Some houses also have a shutoff where the line enters the building. It is worth locating yours before you ever need it, so you are not searching for it during a leak.
It depends on where the break is, what the pipe is made of and how much has to be opened up to reach it. A split in an accessible attic run is a different job from one behind shower tile. Ask the independent plumber for the price of the repair after looking at it and before any work starts, so you are deciding with the number in front of you.
Call Plano 24 Hour Plumber to be connected with an independent plumber; availability depends on the provider and the property location. A burst pipe is urgent, so tell the provider whether the water is already shut off, because that changes how the visit is planned.
If the main water supply is off, switch off an electric heater at its breaker, or turn a gas unit to its pilot or vacation setting, so it is not heating an empty tank. Only do it if the unit is easy to reach and dry. Do not go near a gas connection or an electrical panel standing in water, and skip this step entirely if it is not safely accessible. See water heater repair for more.
Describe where the water is coming from and whether the main valve is off.