Concealed pipe leak vs surface leak — how do I tell?
A Singapore answer for HDB, condo and landed homes — the meter test you can do tonight, and what a licensed plumber checks before anyone hacks a wall.
Concealed pipe leak vs surface leak — how do I tell?
In a Singapore flat, a surface leak shows water at a pipe you can reach — under a basin, at a valve, along a visible run. A concealed leak shows no water at the pipe at all: the clues are a damp patch, bubbling paint, a musty smell, or a PUB meter that still turns with every tap closed.
The distinction matters because the two leaks fail differently. A surface leak is usually a joint, a fibre washer or a flexible hose, and it is repaired where you can see it. A concealed leak is a run buried in a wall, floor screed, ceiling void or cabinet base, so the water travels before it shows — which is why the first sign is often a stain on a neighbour's ceiling rather than a puddle in your own flat.
Symptom to cause: what is actually leaking
| What you notice | Most likely cause | What a licensed plumber checks |
|---|---|---|
| Damp patch or darkened paint on a wall, no water on the floor | Concealed supply or waste joint inside the wall | Meter test first, then moisture readings along the wall to follow the run |
| Stain spreading on the ceiling below a bathroom | Waste pipe or trap above the ceiling board | Ceiling void or access panel, trap and joint check before opening anything |
| Musty smell, cabinet base soft or lifting | Slow seep into screed or cabinet carcass | Moisture meter, isolate the branch, check the joint behind the unit |
| PUB meter turns with every tap closed | Supply-side leak, concealed runs first suspect | Meter test, then isolate the riser to narrow which branch is passing |
| Water appears only when a fixture is used | Waste-side leak, not the supply pipe | Run one fixture at a time and watch the trap, waste arm and floor trap |
| Visible drip under a basin or at a valve | Surface leak — joint, washer or hose | Fitting and hose condition, re-make or replace the part on the spot |
Updated 31 Oct 2026. Table is diagnostic guidance, not a remote diagnosis — a concealed joint can only be confirmed on site.
The meter test you can do before calling anyone
Close every tap, and turn off anything that fills by itself — washing machine, water dispenser, storage heater inlet. Then look at the PUB meter. If the dial keeps moving with nothing open, water is passing somewhere and a concealed supply run is the first suspect. If the dial is still, the leak is more likely on the waste side, which usually shows up only when a fixture is used.
Photo the reading, wait fifteen minutes, photo it again. That pair of photos is the single most useful thing you can send us, because it separates supply from waste before anyone visits.
What happens when you engage AOT
Send the photos and your postcode on WhatsApp. If the fault is visible — a dripping valve, a leaking hose, a joint under the basin — we give a from-price before attending and repair it on the spot. If the run is concealed, we survey first from $50, do the meter test and moisture readings, isolate the branch, and only then quote the opening and repair. Pipe and joint leak repair starts from $80. Labour only — parts and GST are extra.
Coverage is islandwide Singapore, Monday to Saturday 08:00–17:00. We are not a 24-hour service, so we will tell you honestly when we can attend.
Common questions
How do I tell a concealed pipe leak from a surface leak?
A surface leak shows water at a pipe you can reach — under a basin, at a valve, along a visible run. A concealed leak shows no water at the pipe: you see a damp patch, bubbling paint or a musty smell on a wall, floor or ceiling, or the PUB meter still turns with every tap closed.
How do I do the meter test for a concealed leak?
Close every tap and turn off the washing machine and water dispenser, then look at the PUB meter. If the dial keeps moving, water is passing somewhere with nothing open — that is a supply leak, and concealed runs are the first suspect. If the dial is still, the leak is likely on the waste side.
Do I need to hack the wall to find a concealed leak?
Not to find it. The meter test, moisture readings and isolating one branch at a time narrow the run first, so any opening is made where the leak actually is. What gets opened depends on the pipe material and how the run was installed.
Can a concealed pipe leak be repaired without hacking?
Sometimes — an exposed section at a riser, a service yard or a cabinet base can be re-made without opening the wall. If the leak sits inside a wall, floor or ceiling, an opening is needed and the scope and price are quoted after the survey, before any work starts.
How much does concealed leak detection cost in Singapore?
AOT starts with a site survey from $50 and pipe or joint leak repair from $80. Concealed work is quoted after the survey once the run is located, and the price is confirmed before work starts. Labour only — parts and GST are extra.
Related: pipe and joint leak repair · why a floor trap smells · pipe repair · full from-rates
Meter still turning with everything closed?
Send two meter photos fifteen minutes apart and your postcode — we will tell you whether it reads like supply or waste.