Older HDB trunking drip: cracked drain coupling in original route
A Queenstown HDB room had water appearing along the trunking, not directly under the fan coil. In older flats, that detail matters. The leak can start inside the drain route instead of from the visible indoor unit.
By Team Snowflake | Reviewed 15 Jun 2026
Case summary
Mitsubishi Electric Wall-mounted13 years oldHDBQueenstown, Singapore
- Concern
- Client thought the indoor unit tray might be cracked and replacement might be needed.
- Found
- Cracked drain coupling inside the original trunking route
- Key check
- Traced the wet point along the trunking before blaming the fan coil
- Result
- The trunking stayed dry after the coupling was replaced and the drain flow was checked. The customer avoided replacing a working indoor unit, and future leaks can be traced from the first wet point instead of guessing from the unit front.
What we were told
Water appeared along the bedroom trunking after the aircon ran for a while. The fan coil itself did not drip from the front edge, but the wall below the trunking became damp. The concern was a cracked tray.
What we checked
We started by finding the first wet point instead of opening the whole unit immediately. The water line began along the trunking route, which suggested the drain path was involved after the water had already left the indoor unit. We removed only the necessary cover sections to avoid disturbing the older route more than needed.
The fan coil drain pan was not overflowing at the front edge.
The first visible wet point was inside the trunking route.
A drain coupling had cracked where the pipe changed direction.
The surrounding insulation was damp but the wall damage was still limited.
What we found
The drain coupling inside the trunking had cracked with age. Condensate left the indoor unit normally, then leaked from the damaged joint before reaching the discharge point. That made the symptom appear away from the fan coil, which is why the tray looked suspicious at first. The older drain route was the weak point, not the cooling coil or the indoor unit body. Replacement would not have solved the hidden joint unless the route was repaired too.
What fixed it
We replaced the cracked coupling, dried the damp section, and checked the drain fall before closing the trunking. We explained that the repair had to follow the water path, not the most visible unit. The customer was advised to monitor the same first wet point after a full cooling cycle. If water returned elsewhere, the next check would be the remaining drain route rather than a new indoor unit quote.
Outcome
The trunking stayed dry after the coupling was replaced and the drain flow was checked. The customer avoided replacing a working indoor unit, and future leaks can be traced from the first wet point instead of guessing from the unit front.
What this case teaches us
Trunking leaks need the first wet point traced
- Water at the trunking does not prove the indoor unit is leaking from its tray. The drain route can fail after the water leaves the fan coil.
- Older Queenstown flats may still have original drain routes with joints hidden behind covers. Those joints should be checked before replacement is discussed.
- Send photos of where the water first appears. That tells the technician whether to inspect the unit body, the drain coupling, or the trunking route.
Related reading
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