By June every air conditioner in North Texas is running most of the day, and each one is quietly producing water. A central system in humid weather can pull many gallons of condensate out of the indoor air daily, all of it collected in a pan under the indoor coil and carried away by a small drain line. When that line clogs or the pan fails, the water has nowhere to go but into the house, a little at a time, for as long as nobody notices. It is the most common summer water loss we see, and it has a way of becoming a mold problem before it becomes a water problem.
How the drain fails
The condensate drain is a PVC line, often three-quarters of an inch, that runs from the coil to a plumbing drain or to a discharge point outside. Over a season it accumulates algae, dust and biological slime, and it clogs. Well-designed systems have two safeguards: a secondary drain pan under the whole unit with its own line, and a float switch that shuts the system off when water rises in either pan. Many older installations lack one or both, and float switches fail.
In North Texas the indoor unit is frequently in the attic, directly above bedrooms and hallways. An overflowing pan drips onto the attic floor, saturates the insulation, and eventually stains the ceiling below. By the time the stain appears the insulation may have been wet for weeks.
Why the damage is different from a burst pipe
A burst pipe is loud, fast and obvious. A condensate leak is silent, slow and hidden, and that changes three things:
- Materials are wet longer. Insulation, drywall and framing that stay damp for weeks are far more likely to support mold growth than materials soaked once and dried within days. The IICRC S500 standard notes that clean water left in place degrades in category; a slow leak that has been feeding growth for weeks is no longer a simple Category 1 loss.
- Growth is likely by the time you find it. Musty odor in a hallway, a stain that keeps spreading, or a soft spot in the ceiling around a light fixture often means the question is no longer whether there is mold but how much.
- Coverage is complicated. Many homeowner policies exclude damage from continuous or repeated seepage over a period of weeks, and from mold that results from it, while covering a sudden overflow. How a particular leak is classified is your carrier’s decision. Prompt discovery and prompt action help.
What to watch for
- Ceiling stains, especially near an attic access or below where the indoor unit sits.
- Water dripping from the secondary drain outlet outside, which on many homes is a small pipe stub above a window or eave. Water coming out of it means the primary drain has failed.
- A musty odor in one hallway or room with no visible source.
- Higher indoor humidity than usual, or a system that shuts off unexpectedly, which may be the float switch doing its job.
What to do when you find it
- Turn the system off at the thermostat to stop producing water.
- Call an HVAC contractor to clear the drain and correct the pan or switch. That fixes the source; it does not dry the house.
- Have the wet area assessed with moisture meters and thermal imaging. Our post on hidden water damage explains how technicians find how far the water actually traveled, which is usually farther than the stain suggests.
- Where growth is present or suspected, Texas rules apply. Remediation of more than 25 contiguous square feet in a residence must be performed by a licensed mold remediation contractor under a protocol written by an independent licensed assessor. We do not perform testing or abatement ourselves; we coordinate those licensed partners and oversee the project as the general contractor. Our mold remediation services page explains how that works.
Preventing it
Have the condensate line flushed during the spring HVAC service, confirm that a float switch is installed and tested, and look at the ceiling under the attic unit once a month in summer. A ten-second glance at a hallway ceiling is the cheapest inspection you will ever do.
If you have found a stain, a smell or a soft ceiling and are not sure how far it goes, call Fire & Water Restoration Plus at 972-455-8252. We will map the moisture, correct any active water damage, and, if mold is in the picture, explain how the Texas assessment and remediation process applies to your home.