Why is your aircon leaking water?
Woke up to a puddle under your wall unit, or a drip landing on the sofa? It looks bad, but the cause is usually simple.
Every aircon makes water. As warm, humid air passes over the cold coil, moisture condenses and drips into the drain pan. Singapore adds to the load. Meteorological Service Singapore data, as cited in Billy Aircon’s 2026 guide, puts average relative humidity above 80%.
From the pan, the water should flow out through the condensate drain line. That’s usually a PVC drainage pipe running along the trunking to a drain or the aircon ledge. A leak means the water is not getting out the way it should.
Here is the normal path:
- Warm air hits the cold coil and turns to water.
- The water drips into the drain pan.
- It flows down the condensate drain line.
- It exits at a drain or the aircon ledge.
Aircon water leak repair starts from S$60. We find the cause first, then give you a fixed quote. That way, you know the price before any work begins.
Aircon Servicing Jurong is the Jurong service of Cool Earth Aircon, which Brian started in 2007.
Common causes of aircon leaks
| Cause | What you may notice | What we do |
|---|---|---|
| Choked drain line | Drips from the indoor unit, often worse at night | Flush and vacuum the drain line |
| Dirty drain pan | Leak returns soon after servicing, sludge in the pan | Clean and reseat the drain pan |
| Wrong pipe slope or worn insulation | Water stains on the wall, drips along the trunking | Correct the slope or re-wrap the pipe |
Leak repair starts from S$60, with a fixed quote once we know which one it is.
Choked drain line
Dust, mould and slime collect in the drain line until water backs up into the pan and spills out of the indoor unit. This is the most common cause. According to HomeJourney’s 2026 guide to Singapore aircon leaks, clogged drain lines account for about 60% of cases.
We flush the line and use a vacuum pump to pull out the blockage. Most blocked lines show a few signs first:
- Drips or a steady trickle from the underside of the indoor unit
- A musty smell from the unit
- Water that appears after the aircon has run for a while
Dirty drain pan
In older units, jelly sludge builds up in the pan and blocks the outlet. A light build-up can be cleared on the spot. Heavy sludge usually means the unit needs a chemical overhaul to clean the pan properly.
Wrong pipe slope
Water needs a steady downward slope to drain. VD Aircon Services notes that Singapore’s industry minimum drainage gradient is 1%, which means 1 cm of drop for every 100 cm of pipe.
If the pipe sags or runs flat, water sits in it and backs up. We check the pipe slope along the run and correct it.
Quick check: Look along the trunking. A visible dip, or a stretch that runs level, is often where the water is pooling.
Worn pipe insulation
Bare copper pipe sweats in Singapore’s humidity. Water forms on the pipe and drips down the wall or off the ledge. Replacing torn pipe insulation stops it.
Don’t ignore ledge drips. Sky Blue Aircon’s 2026 guide says HDB guidelines make owners responsible for keeping aircon water off neighbours’ ledges and common areas. Sweating pipes usually show up as:
- A damp patch on the wall below the pipe run
- Drips falling off the ledge
- Wet trunking
Faulty drain pump
Ceiling cassette units and some ducted units use a drain pump to lift water out. When the pump fails, water drips from the ceiling. Our commercial aircon servicing covers these units.
Leaks in older Taman Jurong flats
Many flats in Taman Jurong and older parts of Boon Lay still run units on old piping and long trunking runs. Penang Travel Tips notes that Taman Jurong was developed in the late 1960s and early 1970s. Some flats have had a lot of years to wear down.
Over time, insulation tears, pipes sag, and sludge builds in the drain. We see these leak jobs in Taman Jurong often. In an older HDB flat, we check the whole path from pan to outlet, not just the first blockage we find.
A full check covers:
- The drain pan and its outlet
- The condensate drain line
- The pipe slope along the trunking
- The pipe insulation
- The outlet at the drain or ledge
If you live in Jurong West or Jurong East with 2 to 4 wall-mounted units, a leak in one is a good prompt to have the others looked at too. Units installed together tend to age together.
What to do while you wait
Here’s what helps until we arrive:
- Switch the unit off if water is near sockets or wiring.
- Put a towel or tray under the drip.
- Do not pour chemical cleaners into the unit, as residue can make blockages worse.
Angi warns that even diluted bleach can damage your pipes and your aircon. Our guide on cleaning aircon filters yourself explains what is safe to do at home.
Stay off the ledge too. Helpling’s guide advises against climbing onto an aircon ledge or leaning out of a window to check the drain.
Still dripping? Get in touch with Aircon Servicing Jurong for aircon water leak repair from S$60. We’ll find the cause first, and you’ll get a fixed quote before we start.
