In Singapore's humid air, an aircon pulls a lot of water out of the room. That water collects in a tray inside the indoor unit and runs out through a drain pipe. When anything interrupts that path, it ends up on your wall or floor.
What to do straight away
- Switch the unit off.
- Put a towel or container underneath, and move electronics and furniture away.
- Wipe any water from the wall to avoid stains and mould.
The usual causes
1. Blocked drain line
This is the most common cause by far. Dust, slime and mould build up in the drain pipe until water backs up and overflows the tray. Units that haven't been serviced for a while are most at risk. A technician clears it by flushing or vacuuming the line, usually as part of a general service.
2. Dirty filters or coil
When airflow is restricted, the coil can get too cold and ice up. When the ice melts, more water arrives than the tray can handle. Clean filters and a serviced coil usually fix it.
3. Low refrigerant
Low gas can also make the coil freeze, with the same melting and dripping. If you see ice on the pipes, mention it to the technician. See signs your aircon needs gas.
4. Unit not level
If the indoor unit tilts the wrong way, water runs to the wrong end of the tray. This is common after a bracket shifts or after a poor installation.
5. Damaged tray or drain pipe
A cracked tray, a disconnected pipe or a pipe that runs uphill will leak. These need a technician to repair or reroute.
What you can safely check
- Remove and rinse the filters, then let them dry fully.
- Look for ice on the pipes or coil. If there is ice, switch off and let it melt before restarting.
- Check that the drain pipe outlet outside isn't blocked or submerged.
Don't poke wires or tools into the drain from inside the unit, and don't open electrical covers.
What the technician will do
Expect them to clear the drain line, clean the tray and coil, check the unit is level, and test that water flows out properly. If the tray or blower is very dirty, they may suggest a chemical wash or overhaul. Ask to see the problem before agreeing to extra work.
Stopping it from coming back
- Service units regularly, especially ones that run every night.
- Rinse filters every few weeks.
- Don't run the aircon with windows open, which adds humidity and water.
Find companies for general servicing or repair.