Aircon Leaking Water

Water dripping from the indoor unit — what causes it and how fast it is fixed.

Your air conditioner produces litres of water a day; that is normal, because cooling air condenses moisture out of it. What is not normal is that water appearing on your wall, ceiling or floor instead of outside. Nine times in ten the cause is a blocked condensate drain, and it is a same-visit fix. This guide explains the causes in order of likelihood and what to do before the technician arrives.

Quick answer

An air conditioner leaking water inside is usually caused by a blocked condensate drain line, a dirty drain pan, or a frozen coil melting. Turn the system off to stop the water, place a towel or container under the unit, and book a technician. Clearing and flushing a condensate drain in Sydney costs $180–$350 and takes under an hour.

Key takeaways

  • Blocked condensate drain is the cause in the large majority of cases
  • Turn the unit off immediately — running it keeps producing water
  • A frozen coil that melts can look identical to a drain blockage
  • Ducted systems can leak into ceilings unseen; stains mean call now
  • Annual servicing that flushes the drain prevents almost all of these calls

What to do right now

  • Switch the air conditioner off at the remote and, if water is heavy, at the isolator
  • Put down a towel or shallow container to catch the drip and protect flooring
  • If water is near power points or light fittings, keep clear and switch that circuit off
  • Photograph any ceiling stain — it helps us locate a ducted drain fault faster
  • Do not poke wire or skewers into the drain outlet; it damages the pan

The causes, most likely first

  • Blocked condensate drain: dust, mould and slime build a plug, water backs up out of the pan
  • Dirty or cracked drain pan: corrosion or a hairline crack lets water escape before it drains
  • Frozen coil melting: a dirty filter or low gas freezes the coil, then it thaws all at once
  • Incorrect drain fall or a kinked line: installation fault, water never flows away properly
  • Failed condensate pump: common where the drain must be pumped upward
  • Poor insulation on refrigerant pipework: condensation forms on the pipe itself, not the pan

How we fix it

We clear the blockage with nitrogen or a wet vacuum, flush the line, clean and sanitise the drain pan, then verify fall along the full run and watch it drain under load. Where the pan is cracked or the line was installed without adequate fall, we quote the correct fix rather than clearing it and letting you call again next summer.

Ducted systems: the leak you cannot see

A ducted unit sits in the roof space, so a blocked drain dumps water onto insulation and ceiling plaster instead of onto your floor. Brown staining, sagging plaster or a musty smell in a hallway are the warning signs. These are worth acting on immediately — plaster repairs cost far more than the drain clear.

Aircon water leak repair cost in Sydney

Typical pricing for condensate and water-leak repairs.

ItemTypical price
Condensate drain clear, flush and pan sanitise$180 – $350
Drain pan replacement$350 – $700
Condensate pump supply and fit$300 – $550
Re-run or re-pitch of drain line$350 – $900
Pipework insulation repair$180 – $350
Deep clean where mould has formed in the pan and coil$250 – $450

Includes GST and labour. Ceiling or plaster damage from an unnoticed ducted leak is repaired by a trades partner and quoted separately.

Frequently asked questions

Is water leaking from my aircon dangerous?

The water itself is condensate, not dirty water, but it damages plaster, flooring and cabinetry quickly and is a genuine risk near electrical fittings. Switch the unit off and get it looked at promptly.

Why does my aircon only leak on humid days?

Humid air produces far more condensate, so a partly blocked drain that copes on a dry day overflows on a muggy one. It is still a blockage — humidity just exposes it.

Can I clear the drain myself?

You can gently clear the outdoor drain outlet of debris. Anything beyond that risks cracking the pan or pushing the blockage further in, and it will not clean the biofilm causing it.

How do I stop it happening again?

An annual service that flushes the condensate line and sanitises the pan prevents nearly all repeat leaks, and it also catches the filter and coil issues that freeze coils.

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