Water dripping from the ceiling: what to do in the first ten minutes

Water coming through a ceiling has already been running for a while. Drywall absorbs a great deal before it shows on the other side, so by the time you can see it, the space above has been wet for hours at least, sometimes days.

Four things, in this order.

1. Kill the power to that area

Before anything else. Water travels along joists and finds light fixtures and junction boxes. If the drip is coming out of or near a light fitting, switch that circuit off at the panel rather than using the wall switch. Do not stand in water to reach the panel.

2. Shut the water main off

Find the main shutoff - usually where the supply line enters the basement, in a utility room, or at the meter. Turn it clockwise until it stops. Then open the lowest faucet in the house to drain the pressure out of the pipes, which stops water continuing to feed the leak from what is already in the system.

If you do not know where your main shutoff is, find it now while nothing is wrong. It is the single most useful thing a homeowner can know.

3. Relieve the ceiling

This feels wrong and it is correct. A ceiling holding water will eventually come down in one piece, which is far more damage and considerably more dangerous than a small hole. Put a bucket underneath, and with a screwdriver make a small hole at the lowest point of the bulge to let it drain in a controlled way.

If the ceiling is visibly sagging or bulging, stay out from under it and do this from the side.

4. Work out roughly where it is coming from

Water runs along joists before it drops, so the wet spot is often not underneath the source. Still, the likely candidates narrow quickly:

• Bathroom directly above? Failed shower pan, a leaking supply line, a toilet flange, or a tub overflow gasket. Very common.
• Nothing above but roof? A roof leak, or condensation on ductwork in an unconditioned attic. Check whether it correlates with rain.
• Kitchen or laundry above? Supply line to a dishwasher, ice maker or washing machine. Braided supply lines fail suddenly.
• Started in a cold snap? A pipe froze and split. The water often appears when it thaws rather than when it froze.

If the drip continues after you have shut the water main off and drained the system, it is not a supply pipe. That points at a drain line, a roof leak, or condensation.

What not to do

Do not paint over the stain and hope. Do not leave wet insulation in place to dry on its own - it holds water against framing and it is where mould starts. And do not assume that because the drip stopped, the leak stopped; intermittent drips usually mean an intermittent source, like a shower used once a day.

Getting it fixed

Ceiling leaks are one of the situations where finding the source is most of the work. We use acoustic listening equipment and thermal imaging for leak detection so that the access hole goes in the right place the first time rather than in three wrong places first.

If it is a split pipe from a freeze, that is burst pipe repair, and it needs doing before the rest of the run is pressurised again. If it turns out to be a failing water heater in a space above a finished room, replacement is usually the answer, because a leaking tank body cannot be repaired.

Either way, call. Our line is answered around the clock and this is exactly the sort of call that should not wait until morning.