Updated 2026-10-10 · by Seepwise
Short answer: Watch when it drips. If it drips only while the aircon runs, it is almost always the aircon drain or the unit's condensate. If it drips after showers in the flat above, it is the floor slab's waterproofing. If it drips after rain, look at the roof or facade. If it drips steadily whatever happens, suspect a concealed pipe.
Seepwise writes these guides from HDB, MND and BCA sources and published Singapore price data; each claim links to where it comes from.
The four suspects, and how each one behaves
| Drips when | Where | Looks like | Likely source |
|---|---|---|---|
| The aircon is running | Near the indoor unit or its drain route | Clean water, steady drips | Aircon drain line or overflowing tray |
| After showers or floor washing upstairs | Under a bathroom or kitchen above | Brown-edged stain growing outward | Floor-slab waterproofing |
| After rain | Top floor, near walls or windows | Stain that grows with storms | Roof, facade or window |
| All the time, slowly | Along a pipe route | Damp that never dries, rising water bill | Concealed pipe |
Test it in a day
- Aircon test: run the aircon for an hour with nothing else happening. Drips start? Call an aircon technician.
- Upstairs test: ask your neighbour to shower and wash the bathroom floor. Stain grows within hours? It is the slab.
- Meter test: turn off every tap and watch the water meter. Still moving? A pipe is leaking somewhere.
- Rain test: note the stain before and after the next storm.
Why getting this right saves money
Each source needs a different trade. Calling a waterproofing specialist for an aircon drain wastes a visit; hacking a bathroom floor for a pipe leak wastes a floor. The responsibility rules also differ: in HDB flats the slab is shared between owners above and below, while the roof and facade are the Town Council’s (HDB).
If the tests do not settle it
A water leak detection visit combines moisture mapping, thermal imaging, dye tests and pressure tests, and gives you a written finding. Or start with the free leak source checker.
Bottom line
Timing tells you most of what you need: aircon, upstairs, rain or always. Request an inspection and say which pattern you see; the right specialist calls back.
Want this checked at your home?
A specialist calls you back to book an inspection.
Request received.
A specialist will contact you on the number you gave. If water is near electrics, switch off that circuit at the distribution board and keep clear until then.
More questions
Why is my aircon leaking water from the ceiling?
Usually a blocked or disconnected condensate drain line, or a dirty unit overflowing its tray. An aircon technician clears it; it is not a waterproofing job.
How can I tell a pipe leak from a slab leak?
A pipe leak keeps going when nobody upstairs uses water; a slab leak tracks their showers and floor washing. A pressure test on the pipe confirms it.
Which specialist do I need?
Aircon: an aircon technician. Pipe: a plumber. Slab, roof or wall: a waterproofing specialist. A detection visit tells you which.