What to Do When a Pipe Bursts

By the San Antonio 24 Hour Plumber team · Updated September 2026

Shut the Water Off First

Everything else can wait. A supply line under household pressure moves a startling amount of water per minute, and the difference between a two-minute leak and a twenty-minute one is usually the difference between drying a floor and replacing it. Go straight to the main shutoff.

In most San Antonio homes that valve is in the water meter box at the curb, under a rectangular concrete or plastic lid set into the grass near the sidewalk. Lift the lid, and beside the meter you will see a valve — usually a lever or a flat tab. Turn it a quarter turn so it sits across the pipe rather than along it. If the lid is heavy or full of dirt, a screwdriver in the slot gives you leverage. Many houses also have a second shutoff where the supply line enters the building, often near an outside faucet or in a garage wall, and that one is quicker to reach if you know it is there.

Once the water is off, open the lowest faucet in the house — an outside hose bib or a downstairs tub — to let the remaining pressure drain out of the pipes rather than out of the split.

Deal With the Electrical Risk Before the Water

The instinct is to start mopping. Do not do that if water has spread anywhere near outlets, appliance cords, a breaker panel or the base of a water heater. Water on a floor is a shock hazard the moment it reaches an energized fitting, and it does not look any different from harmless water.

If you can reach your breaker panel from dry ground, switch off the circuits covering the affected rooms. If reaching it means walking through the water, leave it and stay out of the area. The same applies to a ceiling that is holding water above a light fitting: keep out from under it, and do not poke a hole in it to let it drain.

Then Protect What You Can

With the water off and the electrical risk handled, move what matters. Lift rugs, get furniture legs onto blocks or foil, and move boxes off a wet garage floor. Open interior doors and windows to get some air moving if the weather allows. If the split is somewhere you can see it and it is still dripping, a bucket and towels are worth putting down.

What not to do: do not try to patch a pressurized line with tape or a clamp while the water is on, do not open up a wall to look for the leak, and do not run the water heater if the whole house supply is shut off. On an electric heater, switch off its breaker. On a gas heater, turn the control to its pilot or off position — but only if you can get to it safely and without standing in water.

Why San Antonio Pipes Burst

Two causes account for most of the calls. The first is freezing. The February 2021 freeze is the reference point everyone here shares, and the lesson it taught is still the right one: the pipes that split were overwhelmingly the exposed ones. Attic runs above insulation, lines in an uninsulated garage wall, outdoor hose bibs without covers and irrigation backflow preventers all sit outside the warm envelope of the house, and when the temperature stays below freezing for a day or two they are the first to go.

The second is age and corrosion. In houses inside Loop 410 built between the 1920s and the 1960s, galvanized steel supply pipe rusts from the inside out. Flow drops away gradually over years, and then a threaded joint or a thinned section lets go, often without any warning drip beforehand. If one section of galvanized pipe in a house has failed, the rest of that run is the same age and in the same condition — which is worth discussing while a plumber is already there.

Service Across San Antonio

Where you are changes the likely cause. In older central neighborhoods the cause is usually corroded pipe. In newer construction north and west, a burst is more often an attic line that froze or a fitting that failed. In Alamo Heights, where original supply lines often sit behind remodeled bathrooms, both possibilities are on the table at once and the diagnosis matters more than the guess.

Wherever the property is, the useful details to have ready are the same: roughly when the house was built, whether the plumbing has ever been replaced, whether the water is now off, and where the water first appeared as opposed to where it has spread to.

Arrange an Inspection

Once the water is off, the job is to find the split and repair it properly rather than patch it. San Antonio 24 Hour Plumber handles burst pipe repair around the clock, and if the source is not obvious, leak detection comes first so that the only thing opened up is the right wall. If the water seems to be coming from under the floor rather than above it, read about slab leak repair instead. When you are ready, tell us what happened and we will plan the visit.