5 Reasons Your Aircon Is Leaking Water Inside

Every aircon produces condensation when it cools air. That water collects in a drain pan and flows out through a drain pipe. When the pipe gets clogged with dust, algae, or slime, the water backs up and overflows inside your room.

This is the cause in most indoor leak cases. It builds up gradually — you might notice the dripping gets worse over weeks. A routine chemical wash or drain flush clears it. If left too long, the standing water can damage the drain pan itself.

You can sometimes spot this early. If water pools around the indoor unit or drips from one corner, the drain is likely blocked. The fix is straightforward and usually part of a standard service visit.

The evaporator coil sits behind your aircon filter. When it gets coated in dust, airflow drops and the coil temperature falls below normal. Ice forms on the coil surface. When the ice melts, the sudden rush of water overwhelms the drain pan.

Frozen coils also happen when the aircon runs on very low temperature settings with reduced airflow — like when the filter is clogged or the fan speed is set too low. The leak tends to be intermittent: heavy dripping when the ice melts, then nothing for a while.

A chemical wash cleans the coil and restores normal airflow. If the coil keeps freezing after cleaning, the issue may be low refrigerant or a faulty sensor — both need a technician to check.

The drain pan catches all the condensation before it reaches the drain pipe. Over time, the pan can crack from age, or shift out of position if the unit was bumped or poorly reinstalled after servicing.

When the pan is cracked, water leaks out before it reaches the drain pipe. When it is misaligned, water pools on one side and spills over the edge. Either way, the drip pattern is usually consistent — always from the same spot.

A cracked pan needs replacement. A misaligned pan can often be repositioned during a service visit. If your unit was recently serviced and the leak started right after, a misaligned pan is worth checking first.

When refrigerant levels drop — usually from a slow leak in the copper piping — the evaporator coil gets too cold. Ice forms on the coil, and when it melts, the water volume exceeds what the drain system can handle.

This looks similar to a dirty coil freeze, but the key difference is that cleaning does not fix it. If your aircon was recently serviced and the coil is clean but ice still forms, low refrigerant is the likely cause.

A technician can confirm this with a pressure check. Topping up the gas is a temporary fix — if the refrigerant leaked out once, it will leak again unless the leak point is found and sealed.

On very humid days, moisture from the air condenses on the cold outer surface of the indoor unit. This looks like the aircon is leaking, but the water is forming on the outside of the casing, not coming from inside.

This is more common when the room temperature is high and the aircon is set very cold. The bigger the temperature gap between the room and the unit surface, the more condensation forms.

It is not a fault — it is physics. Reducing the temperature gap helps. If the condensation is excessive or happens daily, poor insulation around the piping connection may be letting cold air escape, which a technician can wrap and seal.

If the leak is minor and started recently, check your filter first. A clogged filter is something you can clean yourself, and it may resolve a coil freeze. Run the aircon in fan mode for a couple of hours to let any ice melt, then restart in cooling mode.

Call a technician if the leak persists after cleaning the filter, if ice on the coil keeps returning, or if water is coming from an unusual spot. A leak that started right after a service visit also warrants a callback.

Do not ignore a persistent leak. Water damage to walls, ceilings, and furniture adds up fast — and standing water inside the unit accelerates corrosion of internal parts.