Aircon Leaking Water? Don’t Ignore This — 5 Causes & Instant Fixes

💧🛠️ From blocked drain pipes to dirty filters—diagnose and stop your air conditioner from dripping water inside your home

You wake up one morning and notice a damp patch on your ceiling. Or worse—water is actually dripping from your indoor aircon unit onto your floor. You grab a bucket, place it underneath, and wonder: “Is this normal? Will it stop on its own? How much damage is this causing?”

Let me answer those questions right now: No, it’s not normal. No, it won’t stop on its own. And yes, it’s damaging your ceiling, walls, and potentially your health through mould growth.

I’ve seen this hundreds of times. A small drip that homeowners ignore for weeks becomes a ceiling collapse costing R5,000-R15,000 to repair. The good news? Most aircon leaking water problems have simple DIY fixes—especially if caught early.

In this guide, I’ll walk you through 5 common reasons why your air conditioner is leaking water inside your home. For each cause, I’ll explain how to diagnose it and how to fix it—step by step. And when you need professional help, I’ll tell you exactly when to call.

For more troubleshooting help, check same-day aircon repair services and our maintenance checklist. If you have an emergency leak, use our emergency services. Ready to stop that drip? Let’s go.

💧 Why Air Conditioners Produce Water (Normal vs Problem)

First, understand this: all air conditioners produce water. It’s a normal part of the cooling process. Here’s why:

Your aircon pulls warm, humid air from your room. It passes this air over freezing-cold evaporator coils. Moisture in the air condenses on these coils (like water droplets on a cold glass of iced tea on a hot day). This condensation drips into a drain pan and flows out through a condensate drain pipe to the outside of your home.

Normal operation: You might see a small amount of water dripping from the outdoor drain pipe—this is good. It means your aircon is removing humidity from your home.

Problem operation: Water dripping from the INDOOR unit onto your floor or ceiling. This means the condensate isn’t draining properly. It’s backing up and overflowing inside your home.

🚨 Emergency Steps (Stop Damage Immediately)

If water is actively dripping from your indoor unit, take these steps RIGHT NOW to prevent ceiling and floor damage:

Now let’s diagnose why your aircon leaking water problem is happening and how to fix it.

🚰 Cause #1: Blocked Drain Pipe (The #1 Culprit)

This is the most common reason for aircon leaking water inside your home. The drain pipe blockage prevents condensation from flowing outside.

How to diagnose:

• Water is dripping from the indoor unit
• The outdoor drain pipe (plastic tube from the outdoor unit) has little or no water coming out
• The leak started suddenly, not gradually
• You haven’t cleaned the drain line in over a year

Why this happens: Over time, algae, mould, dust, and slime build up inside the drain pipe. This creates a condensate drain blockage. Water backs up, overflows the drain pan, and leaks into your home.

DIY fix (15-30 minutes):

1. Turn off the aircon (remote and isolator switch)
2. Locate the drain pipe exit outside your home (small white or clear plastic tube near outdoor unit)
3. Use a wet/dry vacuum or a small shop vac to suck the blockage out from the outside end
4. If you don’t have a vacuum, try blowing compressed air through the pipe or using a flexible drain cleaning brush
5. Pour a mixture of 1 part bleach to 10 parts water down the pipe to kill algae (wear gloves)
6. Flush with clean water to ensure the pipe is clear
7. Restart the aircon and check if the leak stops

Alternative DIY method (for accessible indoor drain pans): Some aircons have an access point near the indoor unit where you can pour water/vinegar directly into the drain pan to flush the line. Check your unit’s manual.

If the blockage is deep or you can’t access the pipe, call a professional. Read blocked drain causes and repair guide for more information.

🧹 Cause #2: Dirty Air Filter (Indirect but Common)

A dirty filter doesn’t directly cause leaks—but it creates conditions that do. This is why aircon dripping water fix often starts with filter cleaning.

How to diagnose:

• You haven’t cleaned your filter in months
• The aircon has been icing up (you’ve seen ice on the unit)
• The leak is intermittent—sometimes leaks, sometimes doesn’t
• Airflow from the unit feels weak

Why this causes leaks: A blocked air filter restricts airflow across the evaporator coils. Restricted airflow causes the coils to get TOO cold—below freezing. Ice forms on the coils. When the ice eventually melts (when the unit cycles off or you turn it off), a large volume of water floods the drain pan all at once. The pan overflows, causing a leak.

DIY fix (5 minutes):

1. Turn off the aircon
2. Open the front panel and remove the filter
3. Vacuum or wash the filter with warm soapy water
4. Let it dry completely (don’t install wet)
5. Reinstall the filter
6. If there was ice, run the fan only (no cooling) for 2-4 hours to melt all ice before using cooling again

Read our complete filter cleaning guide and maintenance checklist for ongoing prevention.

💨 Cause #3: Low Refrigerant (Gas Leak)

Low refrigerant (gas) is another indirect cause of water leaks—it creates the same freeze-thaw cycle as dirty filters.

How to diagnose:

• The aircon has been cooling poorly or not cooling at all
• Ice forms on the copper pipes or indoor unit
• You hear a hissing sound (possible leak)
• The thick insulated pipe isn’t cold to the touch
• Your electricity bill has increased significantly

Why this causes leaks: Low refrigerant pressure causes the evaporator coils to become too cold (below freezing). Ice builds up on the coils. When the ice melts (during defrost cycles or when you turn the unit off), the water volume overwhelms the drain pan, causing an overflow leak.

Is this DIY? NO. Refrigerant handling requires SAQCA certification (legal requirement). It’s illegal to handle refrigerants without a license. Low refrigerant always means you have a leak that must be repaired.

Professional fix: A certified technician will locate and repair the leak, then recharge the system with the correct amount of refrigerant.

Typical cost: R800-R1,500 for leak detection + R800-R2,500 for gas refill. Read our complete gas refill cost guide and refrigerant leak signs guide.

🧼 Cause #4: Dirty Evaporator Coils

Dirty coils can cause water to “jump” off the coils instead of flowing smoothly into the drain pan.

How to diagnose:

• You can see visible dirt, dust, or mould on the metal fins when you open the front panel
• The leak is persistent even after cleaning the filter and drain line
• The aircon is several years old and has never had a professional deep clean

Why this causes leaks: Dirty or greasy coils prevent condensation from flowing smoothly into the drain pan. Water droplets cling to the dirt, then drip off randomly—sometimes missing the drain pan entirely and falling into your home.

DIY fix (cautious approach):

1. Turn off the aircon at the isolator switch
2. Remove the filter and front panel (if possible)
3. Use a soft brush to gently remove loose debris from the coils
4. Spray a specialized evaporator coil cleaner (available at hardware stores, R150-R300) onto the coils
5. Wait as directed, then rinse gently with a spray bottle (not pressure)
6. Wait for coils to dry completely before reassembling and restarting

Read our complete coil cleaning guide for detailed instructions.

🔧 Cause #5: Poor Installation (Wrong Slope or Damaged Pan)

Sometimes the ac water leak isn’t your fault—it’s an installation problem from day one.

How to diagnose:

• The aircon has leaked since it was installed (not a new problem)
• You’ve tried all other DIY fixes (drain cleaning, filter cleaning) and nothing worked
• The unit doesn’t appear level (use a spirit level on the bottom of the indoor unit)
• The drain pan underneath the coils is cracked or rusted (visible if you can access it)

Why this causes leaks:

• Wrong slope: The indoor unit must tilt slightly toward the drain pipe side (about 5mm slope). If it’s level or tilted the wrong way, water pools and overflows.
• Cracked drain pan: The plastic or metal pan under the coils can crack over time (or be cracked during installation). Water leaks through the crack.
• Disconnected drain pipe: The drain pipe may have come loose from the drain pan connection.

Is this DIY? Maybe (for slope adjustment only).

• Slope adjustment: You can often adjust the mounting bracket to create the correct slope. Loosen the wall bracket screws slightly, tilt the unit, retighten.
• Cracked drain pan or disconnected pipe: Call a professional. The indoor unit needs to be removed from the wall to access and replace the drain pan.

Professional fix: Drain pan replacement costs R800-R2,000 for parts plus labour (R500-R1,000). Re-sloping costs R300-R600 if done by a technician.

Read our installer selection guide to avoid poor installation in the future. For existing installations, request quotes from local technicians to assess and fix the problem.

📞 When to Call a Professional (Don’t DIY These)

After trying the DIY fixes above, if your air conditioner is leaking water persistently, call a professional. Also call immediately if you experience any of these:

Emergency water leak services: If water is actively damaging your ceiling, use our emergency services and read our emergency aircon leak guide.

Related reading: leak detection services and blocked drain causes and repair.

🛡️ Prevention: Keep Your Aircon Dry Inside

The best way to avoid why is my air conditioner leaking water inside panic is regular maintenance. Here’s a simple prevention schedule:

Read our complete aircon maintenance checklist and drain line cleaning guide. Schedule professional servicing through free inspections and maintenance services.

💰 Cost of Repair vs Cost of Ignoring a Water Leak

This is where many homeowners make a costly mistake. They see a small drip and think, “It’s not that bad. I’ll deal with it later.” Then the ceiling collapses.

❓ Frequently Asked Questions About Aircon Water Leaks

✅ Final Thoughts: Don’t Ignore the Drip

A small drip from your aircon might seem harmless. But that drip is a warning sign. Ignore it, and you could face ceiling collapse, mould growth, electrical damage, and thousands in repairs.

Key takeaways for aircon water leak troubleshooting:

• A blocked drain pipe is the #1 cause (80% of leaks): Clean it with a wet vacuum and flush with vinegar every 3 months.
• Dirty filters cause freeze-thaw cycles: Clean filters monthly to prevent ice buildup that floods the drain pan.
• Low refrigerant is a common indirect cause: If you have ice AND water, call a professional for leak detection and gas refill.
• Ceiling leaks are emergencies: Water pooling on ceiling boards can cause collapse within days. Act immediately.
• Prevention is cheap and easy: R50 of vinegar per year prevents R5,000-R15,000 in ceiling repairs.
• Professional help is worth it: If DIY doesn’t work, call a technician before the damage spreads.

Your action plan: First, turn off the aircon and place buckets. Second, try the DIY drain cleaning method (wet vacuum from outside). Third, clean your filter. Fourth, if the leak continues, request quotes from local repair technicians. For emergency leaks, use our emergency services and read our emergency leak guide.