If you are asking why is my air conditioner leaking water, you are not alone. Water leaks are one of the most common air conditioning issues in Australian homes, particularly with wall-mounted split systems. While condensation is a normal part of how an air conditioner works, water dripping indoors, pooling on the floor, or staining walls is a clear sign something is wrong and needs attention.
Quick summary: the most common reasons an air conditioner leaks water
- Blocked condensate drain line
- Dirty or clogged air filters
- Frozen evaporator coil
- Cracked or rusted drain pan
- Incorrect installation or unit not level
- Low refrigerant levels
Below, we break down each cause in detail so you can understand why your air conditioner is leaking, what it means, and what to do next.
1. Blocked Drain Line Causing Water to Leak Indoors
The most common reason for an air conditioner water leak is a blocked condensate drain line.
As your air conditioner cools your home, it pulls moisture from the air. That moisture flows into a drain pan and exits the system through a small pipe. Over time, dust, mould, algae, and general debris can build up inside this pipe.
When the drain becomes blocked, water backs up and leaks from the indoor unit instead of draining away safely.
Common signs
- Water dripping from the indoor wall unit
- Puddles forming underneath the system
- Musty or damp smells when the unit is running
If the blockage is not cleared, the leak will continue and may cause wall or ceiling damage.
2. Dirty Air Filters Restrict Airflow and Lead to Leaks
Dirty or clogged air filters are another major reason an air conditioner is leaking water.
When airflow is restricted, the evaporator coil becomes too cold and can freeze. Once the system turns off, the ice melts quickly and produces more water than the drain system can handle, leading to overflow.
Common signs
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Weak airflow from the vents
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Ice forming inside the indoor unit
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Water leaking shortly after the air conditioner switches off
Regular filter cleaning is one of the simplest ways to prevent water leaks and improve system efficiency.
3. Frozen Evaporator Coil Creating Excess Water
A frozen evaporator coil is a frequent cause behind repeated questions like why air conditioner water leak keeps coming back.
Freezing can occur due to:
- Poor airflow
- Dirty coils
- Low refrigerant levels
- Running the system on very cold settings for long periods
When the ice melts, large amounts of water are released at once. If the drain tray or pipe cannot cope, water leaks into the room.
Common signs
- Ice visible behind the front panel
- Water leaking after the system has been turned off
- Reduced cooling performance
This issue often points to deeper system problems that require professional inspection.
4. Damaged or Rusted Drain Pan Allowing Water to Escape
The drain pan sits underneath the evaporator coil and collects condensation before it flows into the drain pipe.
In older systems, the drain pan can crack, warp, or rust. When this happens, water leaks straight out of the unit instead of draining correctly.
Common signs
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Persistent leaking even when the drain line is clear
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Rust stains or corrosion near the indoor unit
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The air conditioner is more than 8 to 10 years old
A damaged drain pan cannot be repaired permanently and usually needs replacement.
5. Incorrect Installation or Poor Levelling After Install
If your air conditioner is leaking water not long after being installed, the issue may be installation-related.
Indoor units must be mounted with a slight tilt so water flows naturally towards the drain pipe. If the unit is not level, water can pool in the drain pan and overflow into the room.
Common signs
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Leaks started shortly after installation
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Water dripping from one side of the unit
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No signs of blockages or freezing
This is why correct installation matters. If you are unsure whether your system has been installed correctly, it is worth reviewing your options with a professional installer. You can learn more about proper setup and system positioning on our air conditioning installation options.
6. Low Refrigerant Levels Causing Ice and Water Leaks
Low refrigerant does not directly create water, but it often leads to coil freezing, which then causes water leaks when the ice melts.
Refrigerant levels should remain stable. If they drop, it usually means there is a leak in the system, which requires licensed repair.
Common signs
- Poor cooling performance
- Ice on the indoor coil or refrigerant pipes
- Hissing or bubbling sounds
- Ongoing water leaks despite cleaning filters and drains
Running the system with low refrigerant can cause serious damage and should be addressed quickly.
Is Any Water from an Air Conditioner Normal?
Yes, condensation is normal. Your air conditioner is designed to remove moisture from the air, and that water should drain safely outside.
What is not normal is:
- Water dripping inside the home
- Damp walls or ceilings
- Pools of water forming below the unit
If you see these signs, your air conditioner leaking water needs attention.
When to Call an Air Conditioning Professional
You should arrange professional help if:
- The leak keeps returning
- Ice is visible inside the unit
- Cooling performance has dropped
- You suspect refrigerant issues
- Water damage is occurring inside your home
Ignoring a leaking air conditioner can lead to electrical faults, mould growth, and costly repairs.
Need Help Fixing an Air Conditioner That Is Leaking?
If you are still wondering why is my air conditioner leaking water, the safest option is to have it inspected by an experienced technician. Most causes are straightforward to fix when caught early.
If your system is leaking, not cooling properly, or due for professional assessment, get in touch with our team and get a free quote today!
