Aircond leaking water: what to check first
Why an indoor aircond drips, the drain and airflow faults behind it, the checks you can do safely, and when to call a technician.
What usually causes it
A clogged condensate drain line is the most common cause of an indoor aircond leaking water. Dust, algae and sludge can slowly build up inside the drain until the line clogs.
Poor airflow can freeze the evaporator coil, and the coil drips as the ice melts. A dirty filter is often the reason for that poor airflow, so a frozen coil often points back to the filter.
Providers also name bad installation, low refrigerant, and a damaged condensate pan or pump as other causes of a leak.
Checks you can do safely
Switch the unit off at the isolator before touching anything beyond the filter.
Pull out a dirty disposable filter and replace it. A minor drain clog can be cleared with a brush, vinegar, or a 1:10 bleach dilution.
Water from a leak can stain walls, feed mould on the surfaces it reaches, damage electrical components, and create a shock risk.
When to call a technician
Leave refrigerant, compressor, and electrical work to a qualified technician rather than attempting it yourself.
Call one for a deep clog, a frozen coil, or a refrigerant problem. Providers also name bad installation and a damaged condensate pan or pump as causes.
Updated 4 Oct 2026