Older HDB Trunking Drip: Perished Gasket at the Access Panel

A drip along trunking leads to talk of replacing the run through a finished wall. Whether the pipe is cracked or something on it is.

By Team Snowflake | Updated 24 Aug 2026

Teaching case based on recurring Snowflake service patterns; identifying details are combined.

How this presents

Water escaping partway along a trunking run in an older flat, at a point where a removable access panel sits. The pipe either side of it looks sound. The line drains normally when tested.

Setup: Daikin Wall-mounted13-15 yearsHDBQueenstown
Misread as: Cracked pipework that will need the whole run replaced through a finished wall.
Check first: The access points and seals along the run, checked before the pipe itself

What else produces this

A line that drains normally and still lets water out is losing it rather than backing up, and that loss has a specific location. Continuous pipe fails far less often than fittings designed to be taken apart, because those rely on a seal rather than a bond. Inspecting the access points along the run answers the question faster than examining the pipe. On an older installation those seals are the oldest thing in the whole system.

Normal drainage on test rules out a blockage and turns the search into a search for a leak.
Water escaping at a removable access point places the loss at a fitting rather than in the pipe.
A perished gasket at that panel explains how water passes a joint the pipe itself never touched.
Sound pipe either side confirms the run does not need replacing.

Why it happens

Access points seal with a gasket rather than a bond, and gaskets harden and shrink with age. Once one has perished it no longer presses against the mating face, so water finds its way past whenever the line is running. The pipe on either side is unaffected because it was never a joint. The failure belongs to the part that was built to be opened, and it is the part nobody inspects.

What resolution involves

The gasket is replaced and the panel refitted properly, which restores the run without touching the pipe. It is worth checking every other access point on the same installation at the same visit, since they are the same age and in the same condition. Replacing them all together costs very little and removes the next three call-outs.

How to tell it worked

Water put through with the cover still off, and every access point along the run watched instead of just the one that leaked. Others of the same age are usually not far behind it.

Before you approve a quote

The parts built to open are the parts that perish

Continuous pipe rarely fails. Access points, couplings and seals fail because they rely on a gasket.
A line that drains normally and still leaks has a loss at a fitting, not a blockage.
Replace every seal of the same age at one visit. They are all at the same point in their life.

Questions this case answers

Water at the aircon trunking but not under the unit: where is it coming from?

From an access point along the trunking run, usually where a removable panel sits. The gasket there hardens and shrinks with age, stops pressing against the mating face, and lets water past whenever the line is running.

Does a trunking leak mean the indoor tray has cracked?

No. The line drains normally when tested, and water leaving it partway along points to a failed seal at an access point rather than a cracked tray or pipe. The pipe either side of the fitting looks sound.

How old does trunking have to be before the seals give out?

Age matters less than condition, since heat, sunlight and movement harden the seals. When one coupling fails, the rest are usually the same age and in the same condition, so replacing them all at one visit costs little more.

What photo helps most when reporting an aircon leak?

A close-up of the wet point along the trunking, with the access panel in view. It shows whether water is escaping at a fitting rather than mid-pipe, and it confirms the line still drains normally, so the visit can be planned around a gasket.

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Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.

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