Every aircon removes moisture from the air while cooling. That water collects in a tray inside the indoor unit and runs outside through a drain pipe. When water drips into the room, something is stopping it from draining.
Common causes
- Blocked drain: dust, slime or insects block the drain pipe. This is the most common cause.
- Dirty filters: poor airflow lets the coil freeze; when the ice melts it overflows the tray.
- Unit not level or drain without a fall: an installation issue — water can’t flow to the outlet.
- Low refrigerant: causes icing on the coil and pipes, then dripping as it melts.
- Failed condensate pump: cassettes and ducted units often pump water up and away; if the pump stops, water overflows.
What to do
- Switch the aircon off and dry the area.
- Clean the filters.
- Check the drain outlet outside: when cooling, it should drip steadily. If it is dry, the drain is probably blocked.
- Book a technician to flush the drain, check the unit is level and check for icing or a gas leak.
Is it normal for an aircon to drip water outside?
Yes. Water dripping from the drain pipe outside while cooling is normal — on humid days it can be a steady trickle.
Can I keep using an aircon that leaks water?
It’s better not to. Water can damage walls and ceilings, and it is close to electrical parts. Switch it off and have the drain cleared.