HDB bedroom drip after years of use: drain choke behind trunking
A Tampines bedroom unit began dripping after years of normal use. The flat had older trunking and the leak appeared only after longer runtime. That made the drain route the first serious check, not the gas side.
By Team Snowflake | Reviewed 15 Jun 2026
Case summary
Panasonic Wall-mounted12 years oldHDBTampines, Singapore
- Concern
- Client worried the indoor tray was cracked because water appeared near the trunking.
- Found
- Drain choke behind the trunking causing water backup
- Key check
- Checked drain flow and the trunking route before blaming the unit tray
- Result
- The unit ran through a longer cooling cycle without dripping. The case avoided a tray replacement and left a clearer sign to watch: slow drain flow at the trunking route after overnight use or longer afternoon cooling.
What we were told
The bedroom aircon dripped after running through the night. Short use did not always show the leak. Water appeared near the trunking, and the suspected issue was a cracked indoor tray after years of use. The intermittent timing made a quick visual check unreliable.
What we checked
A leak that appears after longer runtime often means water is slowly backing up. We checked the indoor pan, then tested the drain flow through the trunking route. The older route mattered because a small choke can hold enough water to overflow only after sustained cooling.
The pan was not visibly cracked.
Drain flow was slow when water was introduced.
Sludge was lodged behind a trunking section.
The leak point matched where water collected during the drain test.
What we found
The drain line was choked behind the trunking. Water left the indoor unit, then slowed at the hidden section and backed up during longer operation. Because the issue took time to show, quick on-off testing could make the unit look fine. The fault was drainage, not a gas problem and not proof that the indoor tray had failed. The mature HDB route simply needed to be opened enough to clear the blockage and confirm flow. The first wet point also showed that water was escaping after it entered the drain route, not before.
What fixed it
We cleared the choke, flushed the drain route, and ran water through it until flow was steady. We also explained which wet point to watch if the issue returned. If future leakage appears at a different section, the next step would be tracing the remaining route, not assuming the same choke. For this visit, the correct scope was drain clearing and route confirmation, not replacing the indoor unit. That kept the repair proportional to what the drain test actually showed.
Outcome
The unit ran through a longer cooling cycle without dripping. The case avoided a tray replacement and left a clearer sign to watch: slow drain flow at the trunking route after overnight use or longer afternoon cooling.
What this case teaches us
Older HDB leaks often need the drain route checked, not just the unit front
- Water can back up from a hidden drain choke even when the indoor tray is intact.
- In mature estates, older trunking routes may hide low points, sludge, or old joints that only show up after longer runtime.
- Before accepting a tray or unit replacement, ask whether drain flow was checked through the full route.
Related reading
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