Service 02
Leak detection: read the evidence before opening anything
Water follows the path of least resistance, not the shortest one. The stain, the smell, and the damp baseboard are all downstream of the actual failure — so the work is to narrow the possibilities before a single finished surface is touched.
Design conceptMethod
Narrowing from the whole house to one line
Detection is elimination. Each step removes a large part of the system from consideration, which is what keeps the eventual opening small.
Confirm water is actually leaving the system
The meter test settles this. A meter that moves with everything off proves a supply-side loss; a meter that holds still points instead to drainage, condensation, or an intermittent source.
Separate supply from drain
Supply leaks are continuous because the line is always pressurised. Drain leaks are episodic and appear only while something is draining. Timing the appearance of water usually answers this without any tools.
Isolate by zone
Closing individual fixture stops and, where present, branch or unit valves lets whole sections be ruled out one at a time. In a condo, the in-unit valve is often the fastest way to tell whether the loss is yours at all.
Trace upstream from the evidence
Water travels along framing, pipe runs, and slab edges. The wet area marks the exit. Following the likely run backwards, checking for the highest point of moisture, points toward the entry.
Open the smallest useful access
Once the run is identified, a single access point usually confirms it. The goal is one small opening in the right place rather than several in plausible ones.
Signals
What different clues usually mean
Read this as a shortlist of possibilities, not a diagnosis — several of these overlap in real houses.
Observation → what to consider
| What you observe | What it commonly indicates |
|---|---|
| Meter creeps with all fixtures off | Supply-side loss: buried line, slab, irrigation, or a leaking toilet valve. |
| Warm patch on a tile or concrete floor | Possible hot-side slab leak; the hot line loses heat into the slab. |
| Sound of running water with nothing on | Pressurised loss somewhere in the walls or slab, or a toilet fill valve cycling. |
| Ceiling stain below a bathroom | Drain, trap, or shower pan above; note whether it darkens during use. |
| Damp only after heavy rain | Envelope intrusion rather than plumbing — roof, window, or wall penetration. |
| Water under the sink after use only | Trap joint, drain tailpiece, or the sink rim seal, not the supply. |
| Sweating pipes and cool damp cabinet | Condensation, especially on cold lines in an unconditioned cabinet. |
| Bill up sharply with no habit change | Worth a meter test the same day; small continuous losses add up fast. |
Toilets are the quiet culprit
Document before you dry
What this page is not
If water is actively running
Questions
About finding hidden leaks
How do I do a meter test properly?
Turn off every fixture and appliance that uses water, including ice makers and irrigation timers. Note the meter reading or the position of the small leak indicator dial. Wait fifteen to thirty minutes without using any water, then read again. Any movement means water is leaving the system somewhere between the meter and the fixtures.
What does a slab leak feel like?
Commonly a warm patch on the floor if it is on the hot side, the sound of running water when nothing is on, unexplained damp at the base of a wall, or a jump in usage without a change in habits. None of these is proof on its own, which is why the meter test comes first.
Can a leak be behind a wall with no visible stain?
Yes, particularly on concrete-block construction where moisture can travel down inside the wall and exit at the slab edge or outside. A stain tells you where water left the wall, not where it entered — which is why tracing works upstream from the evidence rather than opening the drywall at the wet spot.
Is high humidity ever mistaken for a leak?
Frequently. Condensation on cold supply lines, on toilet tanks, and around air conditioning drain lines produces real water in real places. The tell is that condensation tracks with weather and air conditioning use, while a leak tracks with water pressure or fixture use.
Working out what your plumbing problem actually is?
Note what you can observe — where the water shows up, when it started, and what you already tried, then call. The assistant can also check open times and schedule a visit once you confirm the details.