Why Is My Mini Split Leaking Water? (5 Instant Fixes to Save Your Wall)
You are sitting on your couch, and suddenly you feel a drop. You look up, and your mini split is crying. Water is dripping down the white plastic casing and ruining your drywall.
Panic sets in. Is the unit broken? Do you need to buy a new one? Don’t panic. In 90% of cases, a leaking mini split is a simple maintenance issue you can fix yourself in 15 minutes. It is rarely a mechanical failure.
In this guide, I will walk you through the 5 most common reasons for leaks and how to stop the drip before it destroys your paint.
Cause #1: The Clogged Drain Line (The Usual Suspect) 🦠
This is the culprit 80% of the time. Inside your unit, moisture collects in a “drain pan” and flows out through a small white tube to the outside. Over time, this tube gets clogged with mold, dust sludge, or even a spider web. When the water can’t get out, it overflows the pan and spills into your room.
✅ The Fix:
- Locate the drain hose outside (usually near the outdoor unit).
- Use a Wet/Dry Vac: Put the vacuum hose over the end of the drain line and suck for 30 seconds. This usually pulls the “slime plug” out.
- Flush with Vinegar: Pour a cup of distilled white vinegar into the drain pan inside to kill the mold.
Cause #2: Dirty Air Filters (Frozen Coil) ❄️
If your filters are caked with dust, the unit can’t “breathe.” When airflow is blocked, the evaporator coil gets too cold and freezes over. You will see actual ice on the coils. When the unit turns off, that ice melts all at once, overwhelming the drain pan.
✅ The Fix:
- Open the front panel.
- Take out the mesh filters.
- Wash them in the sink and let them dry.
- Need a deeper clean? You might need a full cleaning kit. 👉 Check out the Best Mini Split Cleaning Kits here
Cause #3: Low Refrigerant (The Ice Block) 🧊
Just like dirty filters, low refrigerant causes the coils to freeze into a block of ice. How do you know if it’s filters vs. refrigerant?
- Check the filters first. If they are clean but you still have ice, you have a refrigerant leak.
✅ The Fix:
You cannot fix this yourself. You need a pro to find the leak and recharge the system. Warning: Do not just “add gas.” You must find the leak first.
Cause #4: Cracked Drain Pan 💔
The drain pan is made of plastic. Over many years (10+ years), or if the unit was installed roughly, the plastic can crack. Water drips right through the crack instead of going into the hose.
✅ The Fix:
You can try to seal it with waterproof epoxy as a temporary fix, but you will likely need to order a replacement pan from the manufacturer.
Not sure which mini split system fits your situation?
👉 Start with 👉 The Ultimate Mini Split Guide (2026)
Cause #5: Bad Installation (The Slope) 📉
Gravity only works one way: Down. If your installer mounted the unit slightly crooked (tilting away from the drain hole), water will pool in the corner and spill over. Also, if the drain hose outside has a “loop” or goes uphill, the water will back up.
✅ The Fix:
- Put a level on top of your indoor unit. It should be perfectly level (or very slightly tilted toward the drain side).
- Check the hose outside to ensure it flows straight down.
Conclusion: Keep It Dry
A leaking mini split is annoying, but it’s usually just a cry for help: “Clean me!” Start with the Wet/Vac method on the drain line. That fixes almost everything.
Want to prevent this from happening again? Regular deep cleaning is the secret. 👉 See our Step-by-Step Guide to Deep Cleaning Your Unit
