A water leak: the first ten minutes

Water does not need a dramatic entrance. A supply line can fail behind a cabinet and run for an hour before anyone notices. A toilet supply can let go while you are at work. The first ten minutes are not about finding the cause or deciding who to blame. They are about stopping the supply, keeping people away from electricity, and limiting how much of the house gets wet.

Work in this order. It is fine to skip a step if it does not apply, but do not skip the first one.

Minute one: people before property

Before you reach for a towel, look at what the water is touching. If you smell gas or see smoke, stop and leave the house. Call 911 or the utility from outside before you touch a valve. Standing water near an outlet, a power strip, a space heater, or an extension cord is an electrical hazard. Water dripping from a ceiling onto a light fixture is the same. Do not walk through it, and do not flip a switch to see if the light still works.

If water is near the electrical panel, leave that area alone and call an electrician or the utility. If a ceiling is bulging, keep everyone out from under it. A ceiling that comes down is heavy, and it usually comes down without warning.

Once the area is safe to enter, shut off the water. Start at the fixture: the angle stop under the sink, behind the toilet, or behind the washing machine. Turn it clockwise until it stops. If that does not slow the leak, go to the main shutoff.

The main valve is often in a basement, a utility closet, a crawlspace, or a meter box outside. Turn it clockwise. If it is a gate valve that has not been moved in years, do not force it with a pipe wrench and risk breaking the stem. If it will not close, call a plumber and say exactly that.

For a water heater leak, shut off the power or the gas first if you can do it safely, then close the cold inlet valve on top of the tank. If the tank itself is leaking, do not relight the burner or reset the breaker until the tank is repaired or replaced. A leaking tank can be a sign of a failed anode or a corroded shell, not a loose fitting.

Minute three: contain what is already out

You are not trying to dry the house. You are trying to keep the water from reaching carpet, furniture, and the rooms below.

• Put buckets, pots, or bins under active drips.
• Lay towels at the edge of the wet area to slow the spread.
• Move rugs, furniture, and cardboard boxes off the floor.
• Lift curtains and anything fabric that is touching wet wall or floor.
• Open cabinet doors so air can move and you can see the leak.
• Check the ceiling below the bathroom or kitchen, and check the closet on the other side of the wall.

Do not use a shop vacuum near water that may be in contact with electricity. Do not drill a hole in a sagging ceiling unless you know what is above it and you can catch the water safely. A small weep hole can relieve a bulge, but a blind puncture can cut a pipe or a wire. If the bulge is growing, keep people out and call for help.

Minute five: find the source without taking things apart

You do not need to dismantle the cabinet. You need to know which system is leaking, because that changes who you call and how soon.

Supply leaks versus drain leaks

Supply leaks run continuously, even when no fixture is in use. The water is usually clear and under pressure. Look at the angle stops, the supply lines, the shutoff behind the toilet, the icemaker line, and the washing machine hoses.

Drain leaks only appear when water is running. The water may be gray or soapy, and it often shows up under a sink after a shower or a load of laundry. A drain leak can also show up as a stain on the ceiling below a bathroom.

The fixtures and appliances worth checking

If you cannot tell whether the water is supply or drain, shut off the main and leave it off. That is the conservative choice, and it buys you time to call.

Minute seven: document before you clean

Take photos and a short video before you mop. Start wide enough to show the room, then move closer to the leak, the damaged material, and any standing water. Include a shot of the shutoff valve and the water line if you can safely reach it.

Note the time you found the leak, the time you shut the water off, and whether the flow slowed. Those details are useful to a plumber, an insurance adjuster, and a restoration company. Keep receipts for anything you buy to contain the damage, and do not throw away wet materials until you know whether an insurance claim will be filed.

Minute ten: decide what kind of call this is

Call now if any of these are true:

• The main valve will not close, or you cannot find it.
• Water is spreading into more than one room.
• Water is near an outlet, a panel, a cord, or a light fixture.
• The ceiling is sagging or has already collapsed.
• Sewage is backing up, not clean water.
• The leak is from the tank of the water heater.
• The water has been running long enough to soak drywall, insulation, or a subfloor.

You can plan a normal appointment if the leak is a single fixture, the supply is fully off, the water is contained, and nothing electrical is involved. A slow drip under a sink with a bucket under it is not an emergency, but it is not a permanent solution either. If you are still unsure which category you are in, call now or wait walks through the same decision in more detail.

If the water stays off

Leaving the main off is a valid choice until a plumber arrives. Do not turn it back on to "see if it fixed itself." A fitting that has failed once will usually fail again, and the second failure often happens when the cabinet is full again.

If you need water in the meantime, fill a few containers before you shut the main, or use a neighbor's tap. Do not run fixtures that drain toward the damaged section. If the house is cold, keep the heat on so the pipes do not freeze while the supply is off.

After the leak is stopped

Water damage does not end when the dripping stops. Drywall, insulation, and carpet hold moisture long after the surface feels dry. Mold can begin to grow in damp materials within a couple of days, which is why the drying step matters as much as the repair.

• Run fans and a dehumidifier in the affected area.
• Remove wet cardboard, paper, and fabrics that cannot be dried quickly.
• Cut away wet drywall or insulation only if you are comfortable doing it and the area is safe.
• Do not paint or patch over damp drywall.
• Check the same spot for several days, especially after the first heavy rain or the next shower.

If the wet area is larger than a towel can handle, or if the water reached a subfloor or a ceiling cavity, call a water damage restoration company. They have the meters and drying equipment to tell whether the structure is actually dry. A plumber fixes the pipe; restoration dries the house. Both may be needed, and the order matters.

The bottom line

Shut off the water, protect people from electricity, contain what is already out, and document the damage before you clean. Then decide whether you are making a plan or making a call. The first ten minutes will not fix the leak, but they decide how much of the house the leak gets to touch.