Water Leaking from Your AC: Causes and Solutions

Water around your indoor HVAC unit is concerning—it can damage floors, ceilings, and walls. Here's what causes it and how to respond.

Why ACs Produce Water

Air conditioners remove humidity from indoor air. Moisture condenses on the cold evaporator coil and drips into a drain pan, flowing out through the condensate drain line.

When this drainage system fails, water ends up where it shouldn't.

Common Causes

Clogged Condensate Drain The #1 cause. Algae, mold, and debris block the drain line over time.

Fix: Clear the clog. You can try flushing with water or using a wet/dry vacuum. For stubborn clogs, call a technician.

Prevention: Pour a cup of bleach or vinegar down the drain annually.

Dirty Air Filter Restricted airflow causes the coil to freeze. When ice melts, it can overflow the pan.

Fix: Replace the filter and let the system thaw before running again.

Cracked or Rusted Drain Pan Older units have metal pans that rust. Any cracks or holes let water escape.

Fix: Replace the drain pan.

Improper Installation If the unit isn't level, water may not flow toward the drain.

Fix: Professional assessment and correction.

Low Refrigerant Causes the coil to freeze, similar to a dirty filter.

Fix: Professional diagnosis and repair of any leak plus refrigerant recharge.

Disconnected Drain Line The drain line can become disconnected or come loose.

Fix: Reconnect and secure the line.

Preventing Water Damage

Float Switch Many systems have a float switch that shuts off the AC if water backs up. Make sure yours is working.

Regular Maintenance Annual tune-ups should include drain line cleaning.

Secondary Drain Pans In attics or over finished spaces, a secondary pan with a separate drain or leak sensor adds protection.

Immediate Steps If You Find Water

1. Turn off the AC 2. Soak up standing water 3. Check if you can identify the source 4. Schedule service if you can't resolve it

Don't ignore water leaks—damage compounds quickly.