Updated 2026-10-11 · AirconList
Short answer: Usually a clogged drain line: algae, mould and debris block it and the condensate overflows, which Singapore's humidity makes worse. Dirty filters can also freeze the coil and drip as it melts, and low refrigerant causes ice on the lines that drips after the unit switches off. Clean the filters first; if it still leaks, the drain line needs clearing.
The four usual causes
Helpling’s guide to aircon problems lists them (Helpling):
| Cause | The sign | The fix |
|---|---|---|
| Clogged drain line (the main cause) | Water dripping from the indoor unit while it runs | Clear the drain line; servicing usually includes flushing it |
| Dirty filters | Weak airflow, then dripping | Wash and dry the filters fully |
| Dirty evaporator coil | Ice on the coil, leaking, musty smell | A chemical wash |
| Low refrigerant | Ice on the pipes; dripping after switch-off | Find and fix the leak, then recharge |
Singapore makes the first one worse: high humidity means units here produce a lot of condensate water, so a slightly blocked drain overflows quickly.
What to do now
- Switch the unit off, and keep water away from sockets.
- Put a towel or container under the drip.
- Check the filters. If they are grey and clogged, wash them, let them dry fully, and refit.
- Watch it for a day. If it still drips, the drain line or coil needs a technician.
What fixing it costs
Most drain blockages are cleared during general servicing, which Helpling publishes at S$50 for 2 wall-mounted units. If the coil and drain tray are dirty, a chemical wash is S$80 a unit for 9k to 18k BTU and S$100 for 24k BTU (Helpling price list).
Stop it coming back
Regular servicing flushes the drain line before it blocks. Helpling suggests every three months for many Singapore homes (Helpling).
Find companies customers mention for leaks or get quotes.
Want an aircon company to quote?
Free. Tell us what your aircon needs; a company calls you back with a price.
Request received.
An aircon company will call you on the number you gave. If water is dripping near a socket, switch that aircon off until it is checked.
More questions
Is a leaking aircon dangerous?
Water near sockets and wiring is a risk. Switch the unit off and keep water away from electrics until it is fixed.
Can I clear the drain line myself?
Helpling describes using a wet/dry vacuum at the drain exit, or flushing an accessible line with equal parts water and vinegar. Turn the unit off first, and call a technician if it keeps clogging.
Why does it drip after I switch it off?
That is usually ice melting: from very dirty filters or coils, or from low refrigerant. Ask for a leak check before paying for a gas top-up.