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First confirm that water is actually passing through the metered supply: turn off every tap and water-using appliance, photograph the meter reading, use no water for at least an hour, then compare the reading. If it moves, check toilets, irrigation, pool or tank top-ups, water-heater discharge, appliances and visible pipework before calling the leak hidden. If the meter stays still, damp may instead come from rain, drainage, waterproofing or condensation. Do not excavate or open walls from a stain alone; a licensed or registered plumber can isolate branches and use acoustic, pressure, tracer, moisture or thermal methods to locate the supply leak with less damage.
This guide is written for South Africa, Australia, New Zealand. Always check local codes, product specifications, licences, and site conditions.
Separate metered leaks from look-alike moisture
The meter confirms water moving through that particular supply. It cannot by itself prove where the water goes, and it may not register roof, stormwater, drainage, waterproofing or condensation faults.
Meter moves with every outlet off
The low-flow indicator turns or the recorded digits increase during a controlled no-use period.
Next checkRepeat the check after confirming toilets, irrigation, appliances, pool and tank top-ups are idle. If movement remains, arrange systematic plumbing isolation and leak location.
Meter stops but a damp patch remains
No metered flow is detected, yet staining changes with rain, showers, humidity, air-conditioning or drainage use.
Next checkInvestigate roof, wall, shower, waste, condensate and ground moisture rather than assuming a pressurised supply leak.
Meter moves intermittently
The indicator is still for periods, then runs even though nobody intentionally opens a tap.
Next checkCheck toilet refill cycles, irrigation schedules, ice makers, water treatment, pumps, pool or rain-tank top-up and hot-water discharge before testing again.
Wet or unusually green ground
One area stays soft, warm, washed out or greener than nearby ground during dry weather.
Next checkKeep people away from unstable ground and buried services. Mark the area and obtain professional leak detection and service-location information before excavation.
Warm floor or hot-water system cycles
A floor zone feels warm, energy use rises, the heater reheats unexpectedly or a discharge pipe runs.
Next checkTreat it as a possible hot-water or safety-control fault. Do not cap a relief or overflow pipe; use an appropriately qualified plumber or service technician.
Sudden active water entry
Water is spreading, a ceiling bulges, a hose or pipe is spraying, or moisture approaches electrical equipment.
Next checkKeep people clear, isolate water and electricity only when safe, and call the appropriate emergency plumber or utility. Do not wait for a one-hour meter test.
Prepare a controlled no-use test
The test is useful only when every legitimate water user is accounted for and the correct meter serves the property.
- Confirm the meter serial number against the bill or utility record and check whether it serves only your property.
- Tell every occupant not to open taps, flush toilets or use water during the test period.
- Switch off or pause irrigation, washing machines, dishwashers, ice makers, water treatment, pool fillers and rain-tank top-up systems according to their instructions.
- Wait for toilets and storage systems to finish filling, then photograph every meter digit and low-flow indicator without disturbing the meter valve or seal.
- Record the start time, end time, meter readings, weather and any equipment that could not be disabled.
- Keep the main private shut-off accessible for an emergency, but leave the meter supply open during the initial test unless the utility instructs otherwise.
- Do not open electrical panels, hot-water safety controls, concealed cisterns, ceilings or underground services as part of this first check.
Choose the next test from the evidence
Confirm the leak before locating it. The correct next step depends on whether the meter moves, whether the moisture follows water use and which system owns the suspected pipe.
| Evidence | What it suggests | Best next action |
|---|---|---|
| Meter moves steadily during no-use test | Active use or leak on the metered supply | Eliminate automatic users, then ask a plumber to isolate fixtures, branches and the private service |
| Meter moves in short cycles | Toilet, top-up valve, irrigation, treatment or appliance operation | Observe timing and isolate one known device at a time using its approved control |
| Meter does not move; stain worsens in rain | Roof, gutter, wall or stormwater entry | Follow the roof-leak and damp-diagnosis pathway rather than opening a water pipe |
| Meter does not move; stain follows shower or drain use | Waterproofing, seal, trap, waste or drainage leak | Stop using the fixture and arrange wet-area or drainage diagnosis |
| Meter moves after the building shut-off is closed | Possible leak between meter and private shut-off, or a valve that does not isolate | Do not dig; ask the utility and licensed plumber to confirm the ownership boundary and test the service |
| Meter stops after one fixture or branch is isolated | Leak lies downstream of that control | Keep the branch off if safe and have the exact system professionally located and repaired |
Deeper guidance
Confirmation and location are separate jobs
The meter test answers whether water moved through the supply during a controlled period. It does not identify the pipe, prove that water entered the building fabric or distinguish a toilet from an underground service. Location comes next through fixture elimination, branch isolation and evidence from the damp area. Keeping these stages separate avoids unnecessary cutting and false confidence.
Slow and intermittent leaks need repeatable records
A small toilet leak or top-up valve may run only when the level falls, while an underground supply leak may run continuously. Photographing the low-flow indicator, digits and timestamps is more useful than saying the meter looked as though it moved. Smart-meter history can reveal overnight patterns, but it still needs comparison with irrigation, appliances and occupancy.
Moisture instruments need context
A moisture meter compares readings in a material; a thermal camera shows temperature differences; acoustic tools listen for energy from escaping water. None independently identifies every leak. Sun, heating, metal, insulation, rain and normal pipe temperatures can mislead. A defensible diagnosis combines instruments with supply isolation, plans, pipe material and the observed water path.
Documentation can protect the repair and the account
Utilities in all three target regions publish property leak tests, responsibility boundaries and, in some areas, concealed-leak relief policies. Eligibility differs and may require prompt licensed repair, invoices and meter photographs. Keep records from the first abnormal bill through post-repair verification rather than trying to reconstruct them after a claim is questioned.
Step by step
Check the bill and the meter identity
Compare recent actual readings with the same season and normal occupancy, while accounting for guests, irrigation, pools, building work and estimated bills. Confirm that the meter serial number matches the account and whether a sectional-title, strata, body-corporate or multi-unit meter is shared. A high bill can result from changed use or an estimated-reading correction, so do not diagnose a leak from cost alone.
Run the first no-use meter test
Turn off every tap and pause all water-using equipment. Once toilets and tanks have finished filling, photograph the complete meter. Use no water for at least one hour, then take a second photograph from the same angle. South African, Australian and New Zealand utilities commonly recommend this comparison. Any increase means water passed through that meter; it does not yet identify the outlet or prove a concealed pipe failure.
Repeat the test after eliminating automatic users
Check toilet bowls for silent trickling and use a food-colouring test where appropriate. Review irrigation schedules, pool and rain-tank top-ups, reverse-osmosis reject water, water softeners, evaporative coolers, ice makers and appliances. A device that cycles briefly can be missed during a quick glance. Pause one known system at a time using its normal control, then repeat a shorter observation to see whether the pattern changes.
Inspect visible supply and discharge points
Use dry tissue around accessible tap tails, flexible hoses, isolation valves, washing-machine and dishwasher connections. Look beneath cabinets and around toilets, water heaters, pumps, tanks and filters. Follow any geyser, cylinder or solar-system discharge pipe to a safe visible point, but never cap it or operate a safety valve speculatively. Fresh deposits, corrosion, swelling or recurring damp are useful evidence even without an active drip.
Map indoor and outdoor symptoms
Record the exact edge and height of stains, warped flooring, swollen cabinetry, musty odour, peeling paint, warm floor areas and sound of water. Outside, note wet soil, subsidence, washed sand, cracked paving and unusually vigorous growth during dry weather. Compare the pattern with rainfall, irrigation, hot-water use and the meter test. Keep children and vehicles away from ground that may be undermined.
Use controlled isolation only within safe boundaries
A plumber may close the building's private main or individual fixture and branch controls while watching the meter. If the meter keeps moving after a sound building shut-off closes, the private service between meter and building becomes a stronger suspect, but the valve itself may not seal and ownership boundaries vary. Do not turn sealed utility valves, force seized controls or excavate around the meter.
Distinguish supply leaks from drains and weather
A pressurised drinking-water leak normally registers on its meter, while a roof leak, failed shower membrane, waste-pipe leak, air-conditioner condensate or groundwater may not. A stain that appears only during rain, showering or draining needs that system tested under controlled conditions. This distinction prevents repairing a sound supply pipe while the actual water path continues.
Commission non-destructive leak location
Give the specialist the meter photographs, calculated change, pipe material, plans, symptom map and isolation results. Depending on the system, they may use pressure testing, acoustic correlation, listening equipment, tracer gas, thermal imaging, moisture mapping or targeted inspection openings. No single tool proves every leak; ask how the reading links to the suspected pipe and where the repair opening should be made.
Repair, verify and retain evidence
Use the appropriately licensed or registered person for the pipe, heater, waterproofing or drainage work. Repeat the same no-use meter test after repair and check the area under comparable conditions. Keep the invoice, diagnosis, before-and-after meter photographs, product details and utility correspondence. Some providers offer concealed-leak allowances only when eligibility, prompt repair and documentation requirements are met.
Expert tips
- Do not close the meter valve during the first leak test; doing so prevents the meter from recording flow through the private system.
- A smart-meter alert is a useful warning, but confirm automatic equipment and inspect the property rather than assuming the sensor has located the leak.
- Never cap a hot-water relief, overflow or discharge pipe to stop apparent water loss; it may be a safety path.
- Thermal cameras show temperature patterns, not water itself. Sun, heating, pipes and insulation can create false patterns without moisture confirmation.
- Avoid blind drilling, cutting or excavation: electrical, gas, drainage and structural services may be close to the suspected pipe.
- If a tenant or unit owner has a shared meter, notify the owner or body responsible for common plumbing before arranging invasive work.
Common questions
How do I use my water meter to check for a hidden leak?+
Turn off every tap and pause every appliance, toilet, irrigation, pool and tank system that can use water. Photograph all meter digits, use no water for at least one hour, then compare. Movement confirms water passed through that meter, but you still need to eliminate legitimate automatic use and locate the responsible system.
Does a moving water meter always mean a pipe is leaking?+
No. A running toilet, irrigation valve, pool top-up, rain-tank top-up, water treatment system, appliance or hot-water discharge can also create metered use. Repeat the test after accounting for each automatic user. Persistent unexplained movement then supports professional isolation and leak detection.
Can I have a hidden leak if the water meter does not move?+
Yes, but it may not be a pressurised leak on that metered supply. Roof water, failed waterproofing, a waste pipe, condensate, groundwater or an unmetered private source can create hidden moisture without moving the meter. Compare the damp pattern with rain and fixture use.
Where should I look first after the meter confirms a leak?+
Start with toilets, irrigation, pool and tank top-ups, water-heater discharge, appliances, filters, pumps and visible connections. These can be silent or intermittent. If none explains the movement, give the evidence to a qualified plumber who can isolate branches before opening finishes.
Can a leak be between the water meter and the house?+
Yes. If a sound private building shut-off is closed and the meter still records flow, the service pipe between the meter and that valve becomes a stronger suspect. The valve may also fail to isolate, and utility ownership boundaries vary, so ask the utility and plumber to confirm before excavation.
What tools do professionals use to find concealed leaks?+
Depending on pipe material and location, they may combine pressure testing, acoustic listening or correlation, tracer gas, thermal imaging, moisture mapping and targeted inspection. Each method has limitations, so the result should agree with meter and isolation evidence before destructive access.
Is a hidden water leak an emergency?+
Treat spreading water, a bulging ceiling, spraying pipe, unstable ground, hot-water safety discharge, or moisture near electricity as urgent. Keep people clear and isolate services only when safe. A slow confirmed meter loss still needs prompt action because damage and water charges continue.
Sources & further reading
We link to official building-code, government and public-health material where a technical or safety claim needs authoritative context. Local rules and adopted code editions can change.
- City of Cape TownDIY guide to finding and fixing water leaksMunicipal step-by-step guidance for isolating a tap, replacing the correct washer and checking the repair without overtightening.↗
- Overstrand MunicipalityDetect water leaksSouth African municipal guidance for confirming unexplained household use with a controlled meter-reading test.↗
- Sydney WaterLeak detectionAustralian utility guidance on meter testing, private-pipe responsibility, licensed repairs and concealed-leak escalation.↗
- Urban UtilitiesHow to check for leaks on your propertyDetailed Australian checklist covering meters, toilets, appliances, irrigation, pool and tank top-up systems.↗
- Water CorporationHow to detect a water leakUtility guidance cross-checking meter tests, smart-meter alerts and professional leak-detection escalation.↗
- WatercareHow to check for leaksOfficial step-by-step meter and property leak checks used before recommending pressure equipment.↗
- Staggs PlumbingHow to detect a hidden water leak in your homeCurrent contractor guide used for content-gap discovery around fixture elimination, branch isolation and non-destructive locating methods.↗
Stop if the work involves structural uncertainty, hazardous materials, heights, live services, gas, serious water damage, or regulated work. Local rules differ—use an appropriately licensed professional where required.