Water Meter Moving With Everything Off? The One-Hour Test
Your water meter is a free leak detector of forensic quality — it measures every litre entering the property, including the ones escaping through a fault. If you suspect a hidden leak, the one-hour meter test settles the question definitively, and a few variations narrow down where the water is going. Here's the full method.
Running the test properly
Close every outlet and silence every consumer: taps off, appliances idle, no toilet flushes, ballvalve-fed tanks full and shut off cleanly (a trickling toilet invalidates everything — fix or isolate it first). Read the meter, photographing the dials including the small sweep hand or digits. Wait one hour minimum without using any water. Read again. Any movement is water escaping between the meter and your outlets. No movement: your supply side is tight, and any damp has another explanation.
Narrowing the location with valve logic
A positive test becomes a location exercise with your stopcock: close the internal stopcock and repeat the test. Meter still moving — the leak is on the underground supply pipe between the meter and the house (your responsibility, and often insurance-relevant). Meter stops — the leak is inside, downstream of the stopcock. Inside leaks narrow further by isolating branches where valves exist: cold storage feeds, the hot cylinder's cold feed, appliance valves — each closure that stops the meter points at that branch.
Reading the rate
The movement speed matters. A sweep hand crawling barely perceptibly is a weep — real, worth fixing, rarely an emergency. Steady visible rotation is a running fault: a passing toilet valve, a weeping cylinder connection, an underground pinhole — book detection promptly. Fast movement with everything genuinely off is a significant escape doing damage somewhere; treat it with urgency and consider isolating overnight until it's found.
What the test can't see
The meter only witnesses metered water: it cannot see waste-side leaks (a leaking trap or soil connection passes no new water), heating circuit losses on a sealed system (watch the boiler pressure gauge for those), or rainwater ingress. A dry meter test with persistent damp redirects the investigation to those categories — which is itself valuable, since it rules out the entire pressurised supply in one hour.
| Result | Meaning | Next step |
|---|---|---|
| No movement in an hour | Supply side tight | Investigate waste/heating/rain |
| Moves; stops with stopcock closed | Internal leak downstream | Branch isolation → detection |
| Moves even with stopcock closed | Underground supply pipe leak | Professional detection; insurer |
| Fast movement, all off | Significant live escape | Urgent — isolate overnight |
The cost of leaving it
Plumbing faults rarely improve with seasoning: drips scale up their seats and become replacements, small leaks soak fabric silently and become ceilings, and marginal components fail completely at the least convenient hour — usually a cold one. The economical moment to fix a diagnosed fault is while it's still minor, on a standard-rate weekday visit rather than the emergency call it's rehearsing to become.
Frequently asked questions
How accurate is the meter test?
Extremely — meters register very small flows. Its main failure mode is user error: a toilet quietly refilling mid-test. Isolate anything you can't trust before starting.
My meter has a small spinning disc — what is it?
A low-flow indicator, designed to show tiny flows a slow dial can't. Any rotation with everything off is escaping water, however slow.
Who's responsible for a leak on the supply pipe?
From the boundary/meter into the house is normally the property owner's pipe. Water companies often assist or have policies for a first repair — worth asking — and trace-and-access insurance cover frequently applies.
Can a leak exist with a negative meter test?
On the pressurised supply, no — the meter would see it. Waste pipes, heating circuits and rainwater paths leak without the meter's knowledge, which is exactly what a negative test tells you to check.
Where this guide's advice ends
Written guidance has a natural limit: it can tell you what usually causes a symptom, but only eyes on your actual pipework can confirm it. If what you're seeing doesn't quite match any pattern described here, or matches several at once, that ambiguity is itself diagnostic information worth giving an engineer. Our vetted local plumbers do this triage daily — and an honest one will tell you on the phone if your problem sounds like a cheap fix, a bigger job, or (occasionally) not a plumbing problem at all.