Why is my aircon leaking water all of a sudden?

Usually because a drain that has been narrowing for years has finally closed. Nothing changed overnight in the aircon — the blockage simply reached the point where the water could no longer get past it.

Can I still use the aircon while it is leaking?

Better not to. It will keep producing water with nowhere to send it, and the wall behind the unit takes it. Switch it off and get the drain cleared.

Will a general service stop the leak?

In most cases yes, because the service includes vacuuming the drain pipe and clearing the tray, which is exactly what a blocked drain needs. If we open it up and find something else, we tell you before doing anything else.

Do I need a chemical overhaul to fix a leaking aircon?

Usually not. An overhaul is for a unit that no longer cools properly or smells even after cleaning. A leak on its own is a drainage problem, and a service is the right job.

How do I stop it happening again?

Servicing every three months keeps the drain clear before it closes. It is the same reason it is worth cleaning a kitchen trap before it blocks rather than after.

We offer same-day servicing, subject to team availability. If it is urgent — a leak, or a unit that has stopped altogether — tell us and we will try to fit you in. Otherwise we book you the next available slot, usually the following day. We are open 8am to midnight every day including public holidays. A leak counts as urgent — tell us and we will try to get to you today.

Aircon leaking water in Singapore

Water dripping from the indoor unit almost always means the drainage path is blocked, not that the aircon is broken. Dirt and mould build up in the tray and drain pipe, water backs up, and it spills into the room. Clearing it is a general service, not a repair.

Written by Wilson Lee, owner and lead technician at LM Brothers Aircond · 10 years in the trade · Reviewed 21 August 2026

Aircon drainage channel packed with black sludge, the usual cause of a leaking unit

Why it happens

An aircon does not make water on purpose, but it always makes water. Warm room air hits a cold coil, the moisture in it condenses, and it runs down into a tray under the coil and out through a pipe. In Singapore that can be several litres a day.

The tray and the pipe stay wet, all year, in the dark. That is ideal for mould and slime, which slowly close the pipe up. Once the water cannot get out fast enough, the tray fills and overflows at the nearest edge — usually the front of the unit, straight down your wall.

So the leak is a symptom of a dirty drain, not a fault in the aircon. The unit is doing exactly what it was designed to do; the water just has nowhere to go.

Water outside is normal. Water indoors is not.

The outdoor unit dripping, or a steady trickle from the drain pipe outside, is the system working correctly. On a humid day that can be a surprising amount of water.

Water anywhere inside the room is not normal — not from the front vent, not down the wall, not pooling on the floor. It will not clear up on its own, and running the unit while it leaks soaks the wall behind it.

What causes it, and what fixes each one

A blocked drain pipe
The most common cause by a wide margin. Years of condensation leave a layer of black sludge inside the pipe until it finally closes. The water backs up into the tray and over the edge.
The fix: The pipe is vacuumed clear from the outlet and the tray is cleaned out. This is part of a general service, so in most cases the leak and the overdue clean are the same job. Aircon general servicing in Singapore
A drainage tray full of dirt
Even with a clear pipe, a tray packed with debris holds water where it should be draining and pushes the overflow forward into the room.
The fix: The tray is removed, cleared and washed as part of the service. Aircon general servicing in Singapore
A frozen coil melting
If the coil ices up, the ice sits outside the tray. When the unit stops and the ice melts, that water lands wherever it likes. Icing itself is usually a filthy filter or low gas, so the leak is the second problem, not the first.
The fix: We find why it is icing before touching the water. If it is dirt, it is a clean. If the gas is low, we look for the leak rather than just refilling it. Aircon repair in Singapore
The unit is not sitting level
A unit knocked out of level, or a bracket that has shifted, tips the tray the wrong way. Rare, but it is the one cause a clean will not fix, and it usually shows up after an install or a wall repair.
The fix: The mounting is checked and reset so the tray falls toward the drain again. Aircon repair in Singapore
A cracked or disconnected drain pipe
If the pipe has split, or come loose above a false ceiling, the water leaves the system before it reaches the outside — often appearing on a ceiling some distance from the unit.
The fix: The run is traced and the damaged section replaced. This one is a repair, and we quote it before starting. Aircon repair in Singapore

The same aircon drainage tray and blower wheel before and after cleaning: mould and grime on the left, clean parts on the right

What you can check yourself

Turn it off first: Switch the unit off at the remote and put a towel or a basin under the drip. Leaving it running while it leaks soaks the wall and does not help anything.
Check whether the outdoor pipe is running: Find where the drain pipe exits outside. If it is bone dry while the indoor unit is wet, the water is stopping somewhere in between — that is a blockage, and it is the usual answer.
Take the filters out and rinse them: The front cover lifts open and the filters slide out. Rinse them under a tap, let them dry, put them back. If the unit was icing because of a choked filter, this can stop it happening again — and it costs nothing.
Look at where the water is coming from: Front vent, one end of the unit, or the ceiling nearby? Telling us that on WhatsApp genuinely narrows it down before anyone travels.

When to call someone

The drain pipe outside is dry while the unit is dripping inside.
You can see ice on the pipes or on the coil.
Water is staining the ceiling or coming from somewhere other than the unit itself.
It has leaked before, been cleared, and come back within a few months.
The wall or skirting is already wet — that stops being an aircon problem and starts being a damp problem.

What it costs

Most leaks are cleared as part of a general service: $50 for one unit, and less per unit if you do several at once. No GST, and the work carries a 90-day warranty.

If it turns out to be a repair rather than a clean, the call-out to diagnose is $50 — and that is free if we do the job. You get one quoted number covering parts and labour before anything starts.

What we will not do is sell you a chemical overhaul for a blocked drain. If a service fixes it, that is what you get.

See the full price list