Yishun flat leaked after servicing: drain pipe reconnected with poor fall
A Yishun flat near the reservoir stayed dry for years, then leaked at a trunking joint soon after a routine service. The mature estate has mixed-age trunking throughout. A pipe reconnected with too little fall is often behind a leak that starts right after a visit.
By Team Snowflake | Reviewed 11 Jul 2026
Case summary
Gree Wall-mounted10 years oldHDBYishun, Singapore
- Concern
- The homeowner worried the trunking pipe itself had cracked or corroded, which would mean opening up the ceiling to fix.
- Found
- The drain pipe was reconnected after servicing with too little fall at the trunking joint, so water drained too slowly and eventually backed up and overflowed
- Key check
- Checked the pipe's fall at the trunking joint before assuming the pipe itself had cracked
- Result
- The leak stopped completely once the pipe's fall was corrected at the joint. The homeowner avoided an unnecessary ceiling opening and pipe replacement for a fault that was never actually there.
What we were told
The homeowner said the flat had never leaked before and started dripping at a trunking joint about a week after a routine service. The drip was slow and steady, always in the same spot. Nothing else in the home had changed around that time.
What we checked
We treated the timing as the strongest lead rather than assuming the trunking pipe had cracked. A pipe failure usually shows a wet patch that grows quickly. A leak that starts gradually after a service more often points at something disturbed during reassembly, such as a joint reconnected without enough fall for water to drain away properly.
The trunking pipe itself was intact, with no cracks, corrosion, or visible damage anywhere along it.
The pipe at that joint sat almost flat, with barely enough fall for water to drain toward the outlet.
Water was sitting in that low section of pipe instead of draining away, and slowly backing up toward the joint.
No other part of the drainage route showed any sign of blockage or separate damage.
What we found
During the last service, the pipe was disconnected at the trunking joint to check the line. It was reconnected without restoring its original fall. With barely any slope left, water could only drain away slowly instead of running straight through. Each time the unit produced condensate, some of it sat in that flat section rather than clearing. Once enough collected, it backed up and overflowed at the joint, which made it look like the pipe itself had failed.
What fixed it
We disconnected the joint, re-laid the pipe with a proper fall toward the outlet, and reconnected it so water drains away rather than sitting in the line. We did not recommend replacing the pipe, since it was never actually damaged. We advised checking the fall at every reconnected joint after future servicing, not just the fittings themselves, since this step is easy to rush.
Outcome
The leak stopped completely once the pipe's fall was corrected at the joint. The homeowner avoided an unnecessary ceiling opening and pipe replacement for a fault that was never actually there.
What this case teaches us
A leak at a trunking joint after service often means poor pipe fall, not a cracked pipe
- A drip that starts near a trunking joint right after a visit often means a reassembly gap, not pipe damage.
- A pipe reconnected with too little fall lets water sit and back up, which can look just like a leak in the pipe itself.
- Ask whether the pipe's fall was checked and restored at the joint before quoting any pipe replacement.
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