# AC leaking water? Here's what's happening, and what to do in the next ten minutes

Your air conditioner is leaking water because the water it normally drains away has nowhere to go. In nine cases out of ten the condensate drain line is clogged, the drain pan is full, and the overflow is finding your ceiling instead. Turn the system off at the thermostat, put a towel down, and read on — most of this you can check yourself in fifteen minutes.

You usually hear it before you see it. A soft drip in the closet where the air handler lives. A brown ring on the ceiling under the attic. A puddle by the garage wall that you're fairly sure wasn't there on Tuesday. It never happens in March. It happens in August, at 11 p.m., the week your in-laws arrive. Air conditioners have excellent timing and no sense of occasion.

*Photo: Sunny City Cooling technician — most AC water leaks are a drain problem, not a machine problem*

## Your AC makes water on purpose — that part is normal

A working air conditioner is a dehumidifier that happens to cool. Warm, wet Florida air passes over the cold evaporator coil, moisture condenses on the coil the way it does on a glass of iced tea, and it runs off into a drain pan and out through a condensate drain line.

In a Tampa Bay summer a normal 3-ton system pulls **5 to 20 gallons of water out of your house per day**. That water is supposed to leave quietly through a PVC pipe and end up on the grass outside. When the pipe blocks, all of it backs up.

So "my AC is leaking water" almost never means the machine is broken. It means the plumbing that carries the condensation away has stopped doing its job.

## The first ten minutes: what to do right now

1. **Turn the system off at the thermostat.** Not just the cooling — set it to Off. Every minute it runs, it makes more water.
2. **Mop up standing water and put down towels.** Water near an indoor unit finds drywall, insulation and flooring fast.
3. **Look at the drain pan under the indoor unit.** Full and still? Blocked drain. Empty but the floor is wet? The leak may be coming from higher up or from the pan itself.
4. **Look at the copper refrigerant lines.** Solid white ice on them means a frozen evaporator coil, and the "leak" is your ice melting. Different problem, same puddle — see below.
5. **Check the air filter.** If you can't see light through it, that's very likely part of your story.

Leave the system off until the pan is empty and you know which of the causes below you're looking at. An AC that keeps running with a blocked drain will keep pouring water into your house.

## The five things that actually cause an AC to leak water

| What's wrong | What you'd see | Can you fix it yourself? |
|---|---|---|
| Clogged condensate drain line | Full drain pan, water overflowing its edge, sometimes a float switch that shut the system off | Usually yes — wet/dry vac on the outdoor end |
| Dirty air filter → frozen evaporator coil | Ice on the coil or copper lines, weak airflow, puddle appears after the unit is turned off | Change the filter, let it thaw, then watch it |
| Cracked or rusted drain pan | Water under the unit while the drain line still flows freely | No — the pan gets replaced |
| Drain line disconnected or improperly sloped | Water at the unit, dry pipe outside | No |
| Low refrigerant | Ice, long run times, warm air from the vents, high power bill | No — a refrigerant leak needs a technician |

Notice what's missing from that list: "the AC is worn out." Water on the floor is a drainage problem. It's one of the cheapest things that can go wrong with a cooling system — as long as you catch it before it soaks a ceiling.

## Why the same house keeps having the same clog — the thing most guides leave out

**Anatoli, who runs Sunny City Cooling, sees this constantly in newer Florida homes.**

> If a homeowner calls three times in two years to have a drain line cleared, I stop looking at the drain line. I get a level out and put it on the air handler. In a lot of new construction the indoor unit was never set level in the first place, or the slab settled and took the unit with it. Now the pan is tilted a couple of degrees the wrong way. Water doesn't run to the drain, it sits in the low corner of the pan. Standing water grows the slime that plugs the line. So the homeowner is paying, over and over, for a symptom, and nobody ever fixes the cause — which is that the unit is out of level.

Our team has more than 60 years of combined experience with Florida drain lines, and this is the single most useful thing on this page, so here it is plainly: **repeat drain clogs are usually a leveling problem, not a cleaning problem.** A correctly leveled air handler drains itself dry between cycles — which, as the [indoor air quality](/services/indoor-air-quality/) section explains, is also why it doesn't smell. A tilted one always has a puddle inside it, and standing water plus Florida warmth grows biological sludge remarkably well.

| Air handler setup | Typical drain-line clearings over 3 years |
|---|---|
| Set level, pan drains dry between cycles | 0–1 |
| Out of level (install or slab settling) | 3–6 |

What to do about it: next time anyone services your system, ask one question — *"Is my air handler sitting level?"* It takes thirty seconds to check and it is the difference between one visit and six.

*Chart: chart 2 drain clogs (data in the table above/below).*

*Photo: Float switch and drain pan test — Florida Ave, Seminole Heights, Tampa FL 33603*

## Why a clogged drain is the most common cause of all

Across the whole catalogue of air conditioning faults, a clogged condensate drain is the single most common cause of water appearing inside a house. It beats every other explanation combined, for a reason that has nothing to do with quality: it is the only part of your AC unit whose job is to handle standing water, continuously, in a warm dark place, for nine months a year.

Two things follow. First, a clogged drain is normal maintenance rather than a fault — which is why quarterly flushing works so well. Second, a drain pan that sits wet between cycles will eventually corrode, and a corroded pan leaks even when the line is perfectly clear. That is the failure people mistake for a mysterious second problem.

## How to clear a clogged condensate drain line yourself

Most homeowners can do this. You'll need a wet/dry vacuum and about twenty minutes.

1. **Turn the system off** at the thermostat and at the breaker.
2. **Find the outdoor end of the drain line.** It's a white PVC pipe, usually ¾", sticking out of an exterior wall near the outdoor unit, often ending a few inches above the ground.
3. **Seal the vacuum hose over the pipe end.** A rag wrapped around the joint makes the seal. Run the vacuum for two to three minutes. You are pulling the blockage out backwards, which is easier than pushing it forward.
4. **Check what came out.** Water, black sludge and something that smells like a pond is exactly right.
5. **Find the access tee** near the indoor unit — a capped T-shaped fitting on the drain line. Pull the cap and pour a cup of distilled vinegar down it. Not bleach: bleach is hard on the pan, the glue and anything metal it touches.
6. **Turn the system back on** and watch the pan for fifteen minutes.

If water still won't move, or if the line clogs again within a few weeks, stop vacuuming and start asking about the level of that air handler.

*Photo: Condensate drain line at the air handler — Safety Harbor FL*

## Where the water shows up, and what the location tells you

| Where you find water | What it points to |
|---|---|
| Directly under the indoor AC unit | Overflowing drain pan, or a corroded pan |
| Ceiling stain below an attic air handler | The same, arriving one floor down |
| At the outdoor unit in heating mode | Normal defrost meltwater |
| Around the base of the indoor unit after shutdown | Melting ice from frozen evaporator coils |
| Wet insulation on the refrigerant lines | Condensation on bare or damaged line insulation |

Only two of those five are a problem with the air conditioning itself. The rest are drainage, and drainage is the cheap half of this trade.

## If there's ice, the story is different

A puddle that appears *after* you shut the AC off, with frost or solid ice on the copper lines, isn't a drain problem. It's a frozen evaporator coil that has begun to thaw, and the meltwater is more than the pan was designed to take at once.

Two things cause the coil to freeze: **not enough air moving across it** (dirty filter, closed vents, collapsed flex duct, failing blower) or **not enough refrigerant in it**. The first one you can fix with a new filter and patience. The second one means the system is leaking refrigerant somewhere, and it will keep freezing until someone finds the leak.

There's a full walk-through on the freezing side of this in our guide on [why an AC keeps freezing up](/learn/problems/ac-freezing-up/).

## Should you keep running the AC while it leaks?

No, and here's the honest arithmetic. Turning the AC off for six hours in August is uncomfortable. Replacing a section of ceiling drywall, the insulation above it and the paint on two walls is far worse, and homeowners insurance treats slow water damage from a known leak less generously than most people expect.

If the drain pan has a float switch and the system has already shut itself off, don't defeat it. That switch just did its entire job.

## How often should you flush the drain line in Florida?

Every two to three months during cooling season, which in Tampa Bay is most of the year — it is the first item on our [maintenance](/services/air-conditioning/ac-maintenance-tune-up/) visit for a reason. A cup of distilled vinegar down the access tee, quarterly. It is the single cheapest piece of AC maintenance that exists, and it prevents the exact failure this page is about.

Homes with pets, homes that run the AC around the clock, and homes where the drain line runs a long way before it exits all deserve the shorter interval.

*Photo: Quarterly drain flush point at a closet air handler — Waters Ave, Tampa FL*

## When it's worth having someone look at it

- The line clears, then clogs again within a month.
- The drain pan is cracked, rusted, or holds water while the line is flowing.
- There is ice on the coil or the copper lines.
- Water reached drywall, ceiling or flooring.
- You can't find the drain line at all, which happens more often than you'd think in attic installs.

## Frequently asked questions

### How do I stop my AC from leaking water?

Turn the system off at the thermostat, then clear the condensate drain line with a wet/dry vacuum at its outdoor end. That resolves most leaks. If the pan refills and overflows again within days, the problem isn't the clog — it's usually an air handler that isn't sitting level.

### Can I still run my AC if it's leaking water?

Not for long. Every cooling cycle produces several more gallons of condensation with nowhere to go. Shut it off until the drain flows freely.

### Should I be worried if my AC is leaking water?

Worry about the water, not the air conditioner. The repair itself is usually minor. The ceiling, insulation and flooring it lands on are not.

### How much does it cost to fix an AC leak?

Clearing a drain line is one of the least expensive service calls in HVAC. Replacing a rusted drain pan, re-leveling an air handler or repairing a refrigerant leak cost meaningfully more. We publish ranges rather than firm numbers, because the honest answer depends on what's behind the wall. Sunny City Cooling isn't booking work yet — see the note at the bottom of this page.

### Why is my AC leaking water when it's turned off?

Because the evaporator coil froze while it was running, and the ice is now melting faster than the pan can drain. Look for frost on the copper lines.

### How can I tell if it's water or refrigerant?

Refrigerant leaves no puddle. It's a gas at room temperature. If there's liquid on your floor, it is condensation — every time.

### How do I stop it from happening again?

Change the filter on schedule, pour vinegar down the access tee quarterly, and have someone confirm the air handler is level. Those three habits prevent the large majority of the leaks we're describing here.

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Sunny City Cooling LLC · Wesley Chapel, FL · (813) 393-7911 · Canonical page: https://sunnycitycooling.com/learn/problems/ac-leaking-water/