AC Leaking Water Inside? Clear the Condensate Drain (Cost)
An AC removes water from the air and drains it away through a small pipe. When algae or sludge clogs that condensate line, water backs up and leaks around the indoor unit. Professional drain line cleaning typically costs $75–$250, and replacing the line $150–$500.
Last reviewed September 2026
Troubleshoot it now
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Is the drain pan full?
Look under the indoor coil for a pan full of water, and check whether water drips from the drain pipe outside when the AC runs.
Signs it's this problem
- Water pooling around the indoor unit or furnace
- A full drain pan under the coil
- The AC shuts off unexpectedly (float safety switch)
- A musty smell near the unit
Why it happens
Warm, humid air condenses on the cold coil and drips into a pan that drains through a PVC line. Algae and dust grow in that damp line and eventually block it; many systems also have a float switch that shuts the AC off when the pan fills.
Not sure? Run the heating and cooling problem finderHow to fix it, step by step
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Safety: Switch off power before working near the unit; water and electrical components don't mix.
AC Leaking Water Inside? Clear the Condensate Drain (Cost) cost
| Job | Typical cost |
|---|---|
| Clear and flush the condensate drain line | $75–$250 |
| Replace the condensate drain line | $150–$500 |
Got a quote? Check if it's fair
Typical professional price for this job: $75–$500
Common questions
Is it normal for an AC to drip water?
Water should drip outside from the drain line, not inside. Water around the indoor unit means a clog, a cracked pan or a frozen coil melting.
How often should I clean the AC drain line?
A vinegar flush every few months during cooling season helps prevent algae clogs.