Shop unit drip traced to algae-blocked drain pipe, not internal leak
Aircon case in Little India, Singapore: water leakage traced to drain pipe blocked by thick algae growth in the warm and humid pipe run, causing water to back up and overflow from the indoor unit after targeted diagnosis checks.
Case details
What client reported
Water keeps dripping from the indoor unit onto the display shelves. Staff mopped it up but it comes back every day. The previous contractor said the unit casing might be cracked.
What we found
The drip pattern was consistent with a drain backup, not a housing crack. The drain pipe ran along a warm ceiling section before reaching the external outlet.
- Indoor unit drain pan was full but not damaged
- No visible crack or deformation on the unit housing
- Drain pipe running along the warm ceiling had no flow at the outlet end
- Disconnecting the pipe revealed thick algae growth blocking the interior
The drain pipe ran through a warm, humid space above the ceiling tiles. Over time, algae built up inside the pipe until flow stopped completely. Water backed up into the drain pan and overflowed from the indoor unit.
What we did
The indoor unit itself is fine — no crack, no internal leak. Flushing the drain pipe and applying an algae inhibitor at the drain pan inlet should restore normal drainage. Periodic drain flushes during servicing will prevent recurrence.
After the drain pipe was flushed and treated, water flowed freely to the outlet. The dripping stopped and the unit ran dry through the rest of the day. No parts were replaced.
Timeline
Day 1
Indoor unit dripping water onto shop merchandise daily
Day 1
Disconnected and flushed the drain pipe to confirm algae blockage before investigating the drain pan or pump
Day 1
Drain pipe flushed and algae cleared — dripping stopped immediately
What we learned
Why warm drain pipe runs breed algae blockages.
- Drain pipes running along warm ceilings or enclosed spaces in commercial units create ideal conditions for algae growth inside the pipe.
- When algae thickens enough to block flow, water backs up into the drain pan and overflows from the indoor unit — mimicking an internal leak.
- Flushing the drain line and applying algae treatment at the source clears the blockage without any indoor unit repair.
Best next step
If your unit is behaving similarly, start with the service path that fits this case before approving broader scope.
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