Water Dripping From the Ceiling: Plumbing, AC or Roof?
A stain that grows, a bulge, a drip. Whether it is a supply pipe, an AC drain pan or the roof decides what you shut off first. How to tell, fast.
August 10, 2026 · 5 min read
Water coming through a ceiling has one of three sources in the homes we work in: a plumbing line, the air conditioning equipment in the attic, or the roof. They need different responses, and the first few minutes are best spent working out which it is while limiting the damage.
First: catch the water and relieve the ceiling
Put a bucket under the drip and move anything valuable. If the ceiling is bulging with water behind the drywall, pierce the centre of the bulge with a screwdriver and let it drain into the bucket. A small controlled hole is far better than a section of ceiling coming down on its own. Then start narrowing the source.
Is the AC running, and has it been humid?
In summer, with the AC running, the most common source by far is the air handler in the attic. The condensate drain line clogs with algae, the drain pan fills and overflows, and water finds the ceiling below. The tell-tales: it is summer, the drip is near where the indoor unit sits, and the water is clean and cool. Turn the system off at the thermostat immediately. That stops the condensate. Then check the secondary drain, a pipe that usually terminates above a window or at an eave; if it is dripping, the primary drain is blocked and the overflow pan is doing its job or has been overwhelmed.
Is it raining, or has it rained recently?
A roof leak shows up during or after rain, often at a spot below a valley, a vent pipe boot, a chimney or a satellite dish mount. The water is often discoloured from the attic insulation and the timing follows the weather. If it is dry and sunny and the ceiling is wet, it is not the roof. If it is raining and the AC is off, it probably is.
Is there plumbing above?
A bathroom, a laundry room or a water heater above the wet spot points at plumbing. A constant drip regardless of weather or AC use, or one that surges when a fixture upstairs is used, is a supply or drain line. Supply leaks run whether anything is in use, and they are the ones that put the most water through in the shortest time. Drain leaks appear when the upstairs shower, tub or toilet is used and stop when it is not.
The attic water heater
A large share of two-storey homes in Collin and Rockwall counties have the water heater in the attic. A failed tank puts forty or fifty gallons into the pan, and if the pan drain is blocked or missing, through the ceiling. Water that is warm at first, and a drip location under the heater, is the clue. Close the cold water valve on top of the heater and, on a gas unit, turn the control to off; on an electric unit, switch off the breaker.
What we do on arrival
Confirm the source with a look in the attic and moisture readings on the ceiling. Clear a condensate drain and check the float switch that should have shut the system off before the pan overflowed; if there is no switch, we fit one. Locate and repair a supply or drain leak, which may mean opening the ceiling at the wet point. For a roof leak we tell you it is the roof, and you call a roofer; we do not want to guess at that for you.
After the water stops
Get air moving across the wet area with fans. Drywall that has been wet for more than a day or two often needs replacing, and wet insulation above it will not dry in place. Photograph everything for insurance. And take the opportunity to fix the thing that let a small failure become a ceiling repair: the overflow switch, the pan drain, the leak-detection sensor. The next leak is a question of when.
Family-owned in Rockwall, licensed and insured. TX Master Plumber TXM11693, TX HVAC TACLB2360E. (469) 338-5533, 24/7.
Frequently asked
The ceiling is wet but I cannot find a drip. Where is the water coming from?
Water travels along joists and pipes before it shows. The wet spot is the low point, not the source. A moisture meter and a look in the attic find the origin; do not open the ceiling at the stain first.
Can I run the AC if the drain pan overflowed?
Not until the drain is cleared. Every minute it runs produces more condensate that has nowhere to go. It is a short repair; the ceiling is not.
Will the ceiling need to be replaced?
A ceiling that dried quickly and did not sag can often be repainted after a stain-blocking primer. One that sagged, stayed wet or grew mold needs the section cut out.
Does insurance cover a ceiling damaged by a leak?
Sudden leaks are usually covered; long-term seepage often is not. Document the timeline and photographs before cleanup. The plumbing repair itself is typically not covered.