Water is dripping from the indoor air handler, pooling around the furnace closet, or worse — showing up as a stain across the ceiling below an attic unit. Unlike most AC faults, this one is a race against water damage: the sooner you stop the leak, the less drywall, insulation, and flooring you lose. We treat these as urgent all summer across the East Bay and Tri-Valley.
Your AC is supposed to produce water — condensation pulled from the air — but it should drain away, not into your house. This page explains where the water is escaping, what to do right now to stop the damage, and when it's time for a tech.
How it usually shows up:
- Water dripping or pooling under the indoor unit or in the furnace/air-handler closet.
- A ceiling stain or drip below an attic-mounted air handler.
- The float switch tripped and the whole system shut off (a built-in flood safety).
- A musty smell or visible mold near the unit or the drain.
Why your AC is leaking water
The water always comes from the same place — condensate the coil pulls from the air — but it escapes for a few reasons, roughly in the order we find them:
- A clogged condensate drain line. The most common cause by far. Algae and sludge build up in the drain, water backs up, and the pan overflows. Clearing the line is usually straightforward.
- A cracked or rusted drain pan. The pan under the coil corrodes or cracks and lets water drip straight through instead of draining.
- A frozen coil that's melting. A coil that iced up from low refrigerant or poor airflow dumps far more water than the drain can handle when it thaws. The leak is the symptom; the freeze is the disease.
- A failed condensate pump. Basement and attic units that can't drain by gravity rely on a small pump; when it fails, the water overflows.
- A dirty filter driving a freeze-up. A clogged filter chokes airflow and freezes the coil, and the melt overwhelms the drain.
- A disconnected or poorly sloped drain. A drain line that's come loose or was never pitched right simply spills instead of draining.
The usual fix
Our tech first stops the leak and clears the water, then finds the source: flush the condensate drain, replace a cracked pan, repair or replace a failed condensate pump, or — if the coil froze — thaw it and address the airflow or refrigerant problem behind the freeze. If a dirty filter caused the freeze, that's the cheap part; if the coil iced from low refrigerant, the leak has to be fixed, not just topped off. You get a firm, upfront quote before any part goes in.
DIY vs. calling a pro — the honest version
Safe to check yourself first (free):
- Turn the AC OFF right now to stop producing condensate and limit the damage while you find the source. If the float switch already shut it down, leave it off.
- Check and clear the drain line. Find the condensate drain (usually a white PVC pipe near the indoor unit); a wet/dry vac at the outdoor termination can pull a clog free.
- Replace a dirty filter. If a clogged filter froze the coil, a fresh one is the first step to stopping the leak.
- Empty the drain pan. Sponge or vacuum out standing water in the pan so it isn't overflowing while you wait.
Call a pro when:
- The leak comes back after you clear the drain, or you see mold or a musty smell.
- The condensate pump is dead (attic or basement units) — water will keep overflowing until it's replaced.
- The coil keeps freezing and melting, which points to low refrigerant or a deeper airflow fault.
- Water has reached the ceiling, drywall, or electrical — don't wait on that one.
Standing water around an air handler sits next to line-voltage wiring, and a refreezing coil signals a refrigerant problem — this is where a licensed tech pays for itself.
What it costs in the Bay Area
Most leaks are inexpensive to fix: clearing a clogged drain, resetting a tripped float switch, or replacing a cracked pan or condensate pump is modest drain-side work rather than major-component repair. The cost climbs only when the leak traces back to a frozen coil from low refrigerant, where a leak repair plus recharge runs roughly $180–$650. We charge a diagnostic fee that's credited toward the repair once you approve the work, and you'll always get a flat, upfront price before we start — no surprise line items.
Stop the leak — get a tech out today
Triton repairs central AC, heat pumps, and mini-splits across the East Bay, Tri-Valley, and Peninsula — Dublin, Livermore, Pleasanton, San Ramon, and Hayward. Because a leak means active water damage, these get our soonest slots.
Book online or call (888) 993-5699. Turn the AC off to stop the water, then we'll find the source and dry you out.
Related pages
- HVAC Repair in the SF Bay Area — our full heating & cooling hub
- AC Frozen Coil / Ice on the Unit — the freeze-up behind a melt-driven leak
- AC Not Cooling / Blowing Warm Air — the cooling side of the same faults
- HVAC & AC Repair in Dublin — Tri-Valley service area
Frequently asked questions
Why is my AC leaking water inside the house? Your AC pulls water out of the air as condensation, and it's supposed to drain away. When it leaks indoors, the usual cause is a clogged condensate drain line that backs up and overflows, a cracked or rusted drain pan, a failed condensate pump on an attic or basement unit, or a frozen coil that dumps more water than the drain can handle when it melts. Turn the AC off to stop the damage and clear or check the drain first.
Should I turn my AC off if it's leaking water? Yes — turn it off right away. That stops the coil from producing more condensate and limits the water damage while you find the source. If a float switch already shut the system down, leave it off; it tripped on purpose to prevent a flood.
Is a leaking AC an emergency? It can be, because it's active water damage: dripping onto drywall, ceilings, flooring, or electrical adds up fast, and standing water plus mold makes it worse the longer it runs. Turn the system off, clear the drain if you can, and get a tech out quickly — leaks near a ceiling or electrical shouldn't wait.
Why is water dripping from my ceiling under the attic AC? An attic air handler that leaks usually has a clogged drain line, a cracked secondary pan, or a failed condensate pump, and the water follows the path of least resistance down through the ceiling. Because attic units often can't drain by gravity, a dead pump is a common culprit. Shut the system off to stop the flow and have the drain and pump checked.
How much does it cost to fix an AC water leak in the Bay Area? Most leaks are inexpensive: clearing a clogged drain, resetting a float switch, or replacing a cracked pan or a condensate pump is modest drain-side work. It costs more only if the leak traces back to a frozen coil from low refrigerant, where a leak repair and recharge runs roughly $180–$650. We credit the diagnostic fee toward the repair and quote a firm price before any work begins.
Do you offer same-day AC repair near me? Yes — we serve the East Bay, Tri-Valley, and Peninsula including Dublin, Livermore, Pleasanton, San Ramon, and Hayward, and because a leak means active water damage these get our soonest same-week and often same-day slots. Call (888) 993-5699 to book.