Aircon Leaking Water: Causes, Fixes, and When to Act

An aircon leaking water is never normal and always requires quick attention. A standard 9,000 BTU split-type unit in Singapore generates 1-3 litres of condensation every hour. That water is supposed to flow through a drainage tray, down a PVC pipe, and exit safely outside your home.

When any part of this chain breaks, the water takes the path of least resistance, often spilling directly onto your flooring.

Why aircons produce so much water

Air conditioners dehumidify as part of the cooling process. Warm, humid air hits the cold evaporator coil, causing water vapour to condense into liquid. Singapore’s average humidity around 80% forces units to extract massive amounts of moisture year-round. This places immense strain on drainage systems.

The 4 common causes

We categorize indoor water leaks into four mechanical failures:

• Blocked drainage pipes (60% of cases)
• Dirty evaporator coils (15% of cases)
• Incorrect installation tilt (15% of cases)
• Frozen coil thawing (10% of cases)

Cause 1: Blocked drainage pipe (60%)

Mould and bacterial biofilm grow rapidly in the dark, damp drainage pipe. Standard 16mm HDB drainage tubes are especially susceptible. As sludge builds, water backs up behind the blockage, overtops the tray, and spills from the unit.

Signs: Leak worsens the longer the aircon runs. No water or only a slow trickle at the external exit. Mouldy smell accompanies the drip.

Fix: High-pressure compressed-air flush clears the blockage in 30-60 minutes. Severe biofilm requires a full chemical wash to prevent recurrence. Standard flush pricing: S$80-S$150.

Cause 2: Dirty evaporator coil (15%)

A severely fouled coil prevents condensation from flowing cleanly into the drainage tray. Dust and grime alter surface tension, causing water to drip off the front of the coil instead of tracking down into the tray.

Signs: Water drips from the front of the unit. System struggles to reach set temperature. Visible dark residue on the fins behind the vent.

Fix: Deep chemical wash dissolves the grime and restores proper water flow. Surface-level servicing cannot penetrate deep enough.

Cause 3: Installation tilt problem (15%)

Indoor units need a slight downward angle toward the drainage outlet. If the unit is perfectly level or tilted backward, water pools in the tray and overflows.

Signs: Consistent leak from one specific side. Dripping has occurred since installation. System is relatively new.

Fix: Technician re-seats the unit with the correct 1% minimum gradient. Water is poured into the tray to verify the new flow rate. Our 90-day workmanship warranty covers this adjustment for units installed by iCare Aircon.

Cause 4: Frozen coil thaw (10%)

Ice builds on the coil when cooling issues drop evaporator temperature below freezing. When you switch off or select fan mode, the ice thaws rapidly and produces more water than the tray can hold.

Signs: Sudden leak coincides with cooling problems. Cracking or hissing sounds as ice forms. Frost visible on outdoor copper pipes.

Fix: Resolve the root cooling issue, whether it is a clogged filter, refrigerant leak, or failing compressor. See our aircon not cold guide for full diagnosis.

Immediate steps before the technician arrives

Isolate power to prevent electrical damage. Running a leaking unit risks shorting out the PCB, which costs S$150-S$300 to replace.

1. Switch off using both the remote and main wall breaker.
2. Catch the water with a bucket or thick towels under the drip.
3. Do not restart the unit.
4. Photograph exactly where the water escapes.
5. Check the external drainage exit to assess blockage severity.
6. WhatsApp us with photos and your postal code.

Why we often bundle chemical wash with leak repair

Drainage blockages are almost exclusively driven by biological biofilm. A compressed air flush temporarily clears the physical clog, but microscopic bacteria remain on the pipe walls. Without chemical treatment, the blockage recurs within three months.

Alkaline-based washes dissolve the protein-based slime that air pressure alone cannot dislodge. Comprehensive cleaning packages currently range from S$92.65 to S$114.45 per unit in Singapore, inclusive of 9% GST.

What the repair visit looks like

Step	Action	Time
1	Arrival and leak pattern confirmation	5-10 min
2	Drainage tray inspection for slime	10 min
3	High-pressure drainage pipe flush	15 min
4	Evaporator coil and blower inspection	10 min
5	Installation tilt check	5 min
6	Diagnosis and transparent quote	5 min
7	Same-day fix (standard components)	Variable

Total on-site time typically ranges from 60-90 minutes for a drainage flush. Bundled chemical wash extends the visit to over two hours.

The real cost of delay

A simple S$80 drainage repair ignored for a few days can result in massive secondary damage. Replacing water-damaged parquet flooring in Singapore costs S$300-S$700 per room. A few drops over one day is a minor annoyance, but continuous dripping for three days warps timber flooring and deeply stains ceilings. The true cost of delay is often 5-10x the repair itself.

Our repair service team handles these emergencies quickly. WhatsApp your leak photo and postal code to secure a same-day slot.