Why is my Daikin aircon leaking water from the indoor unit?
Water coming out of a Daikin indoor unit is almost never a fault inside the unit. It is the drain path. Where the water appears, and when it started, tells you which part of that path has given way.
By Team Snowflake | Updated 18 Aug 2026
The water is condensate that did not reach the drain
Your Daikin pulls moisture out of the room air. That is what cooling does. Warm air meets a cold coil, water drops out of it, and the tray underneath catches it. From there it should run away down a pipe.
A leak means that water stopped somewhere along that route. The coil is still doing its job. The drain is not.
This is why a leaking Daikin often still cools normally. Owners find that confusing, and it is actually the most useful clue on the whole page. If the room is still getting cold while water drips, the cooling side is fine.
It also sets the order of investigation. The drain path is cheap and quick to check. The unit is not. Nothing should come apart until the drain has been ruled out.
Where it appears narrows it in one look
Three positions cover most leaks, and each points somewhere different. Look before you wipe anything.
Water at the bottom edge of the indoor unit means it backed up and spilled over the tray lip. The blockage is at the tray outlet or in the first stretch of pipe.
A ceiling or wall stain away from the unit means the water left the unit and escaped later. Something along the concealed run is holding it: a dip in the pipe, a joint, or a section squeezed out of shape.
Water at a trunking seam is usually the sweating pipe described above, or a perished seal on an access panel.
| Where the water shows | Most likely source | What it is not |
|---|---|---|
| Where the water showsBottom edge of the indoor unit | Most likely sourceTray outlet or first pipe section, blocked | What it is notA refrigerant problem |
| Where the water showsCeiling stain away from the unit | Most likely sourceA dip, joint or crushed section in the hidden run | What it is notThe unit overflowing |
| Where the water showsTrunking seam | Most likely sourceBare pipe sweating, or a failed panel seal | What it is notDrain water, in many cases |
| Where the water showsOnly on humid days | Most likely sourceA narrowed drain the unit can outpace | What it is notA full blockage |
| Where the water showsIn bursts after the unit stops | Most likely sourceIce melting off the coil | What it is notA drain fault |
Two things to note before you call
Whether the drip is steady or comes in bursts. A steady trickle while the unit runs points at a restriction. Bursts after shutdown point at ice melting off the coil, which is a different fault.
The date it started, and what happened the week before. Servicing, renovation, a shelf going up, a spell of wet weather. That detail solves a good number of these.
If it started soon after a service visit
A leak that begins within days of servicing is usually a reassembly issue. It is worth saying plainly, because the natural assumption costs money.
The instinct is that a fault was found and left behind. The likelier explanation is that a part went back slightly differently from how it came off.
The drain hose is the common one. Reconnected at a slightly upward angle, it still passes water at a steady trickle and backs up once volume rises. On units with a pump, a non-return valve fitted the wrong way round behaves even more oddly: fine while the pump runs, leaking between cycles.
How to raise it
Give the date of the service and the date the leak started. Ask for the drain path to be checked before anything else. That is a fair request and a competent technician will not push back on it.
Do not open with blame. Reassembly slips are ordinary and usually honest. The aim is dry walls, not an argument.
Cassette and ducted Daikins fail differently from wall units
Ceiling units carry a condensate pump. Wall-mounted units usually do not. That one difference changes both how they fail and how the leak shows itself.
A pump adds a reservoir, a float switch and a discharge line. All three silt up over years. The pump rarely fails outright. It slows down, or the float stops rising far enough to switch it on, and the unit floods on a humid afternoon while running perfectly well.
Ceiling units also run their drain flat for a stretch before it drops. Sludge settles along that flat section first. A wall unit usually has fall from the start, so it tolerates buildup that would stop a cassette.
What to do now
Photograph the water where it sits, before you wipe it. Stain patterns tell a technician more than a description, and they dry faster than an appointment arrives.
Switch it off if water is reaching a ceiling void, a wall cavity or anything electrical. Otherwise a drain leak is not an emergency. The water is clean condensate on the outside of a sealed system, and the unit is not damaging itself while it drips.
Put a towel down and leave the unit off until someone looks. Running it makes more condensate, and more condensate makes a bigger leak.
Then push back on any quote that starts with a chemical overhaul or a parts inspection. The drain path takes minutes to check and it is where the answer usually is. If it does turn out to be the unit, that will still be true afterwards.
What a proper drain clear involves
The line gets flushed from the tray end and cleared from the outlet end, so the blockage moves out rather than further in. The tray is cleaned, because the sludge that blocked the pipe came from there and will do it again. Where a pump is fitted, the reservoir and the float are cleaned too.
Then it gets tested under load. The unit runs long enough to make real condensate, and the drain is watched while it does. A line that passes a jug of water can still fail on the volume a working coil produces.
Ready to get started?
Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.