How-to
The Meter Test: Check for a Hidden Leak in 30 Minutes
Use your water meter to find a hidden leak at home. A simple 30-minute DIY test that needs no tools and could save you hundreds on your water bill.
Published 29 June 2026
Why a Hidden Leak Is Worth Finding Today
A slow, hidden leak can waste thousands of litres of water before it shows up as a damp patch or a swollen water bill. The good news is that your water meter — fitted to the vast majority of homes in the TW postcode area — is a surprisingly accurate detector. You do not need any special tools, and the whole test takes about 30 minutes.
Before You Start
You will need:
- Access to your water meter (usually in a small plastic box set into the pavement outside your front boundary, or occasionally inside near the stopcock)
- A torch if the meter box is dark
- A pen and paper, or your phone camera
- 30 minutes during which nobody in the household uses any water
Make sure you account for appliances too. Check that your washing machine, dishwasher, and ice maker are all switched off and mid-cycle is not running. Even a dripping tap inside the house will skew the result, so do a quick walk-round first.
Step 1 — Locate and Open the Meter Box
The meter box lid usually lifts with a flathead screwdriver or simply by pressing a tab. Inside you will find the meter itself. Brush away any debris or standing water so you can read the dials clearly.
Step 2 — Note the Reading
Most meters in this area display a row of black digits (cubic metres used) followed by red digits (litres). Write down or photograph the entire reading, including the red digits.
Some older meters have a small triangular or star-shaped leak indicator dial — a separate pointer that spins even when very little water moves. If this is already turning with all taps off, that alone confirms a leak.
Step 3 — Wait 30 Minutes (Use No Water)
This is the critical part. Thirty minutes of zero water use gives the meter enough time to register even a slow drip. Avoid:
- Flushing the toilet
- Running a tap
- Using any water-fed appliance
If you have an automatic garden irrigation system, make sure it is paused.
Step 4 — Read the Meter Again
Return to the meter and note the new reading. Compare it with your earlier figure.
Interpreting the result
| Change in reading | What it suggests |
|---|---|
| No change at all | No detectable leak on the supply pipe |
| Small increase (a few litres) | Possible slow leak — worth investigating further |
| Noticeable increase | A leak is very likely present |
Even a difference of 5–10 litres over 30 minutes points to a leak that could amount to 240+ litres a day.
Step 5 — Narrow Down the Location
If the meter test shows movement, the next step is to work out whether the leak is on the supply pipe between the meter and your stopcock, or inside the property.
- Turn off your internal stopcock (usually under the kitchen sink or where the pipe enters the house).
- Wait five minutes, then check the meter again.
- If the meter stops moving — the leak is inside your home (toilet cistern, a tap, a radiator valve, or a pipe joint).
- If the meter keeps moving — the leak is on the underground supply pipe between the meter and your stopcock. This section is your responsibility as a homeowner and will need a plumber.
Common culprits inside the home
- A constantly running toilet cistern (add a few drops of food colouring to the cistern — if colour appears in the bowl without flushing, the flapper valve is leaking)
- A dripping tap or showerhead
- A slow weep from a radiator valve
- A pinhole in a pipe behind a wall or under a floor
What to Do If You Find a Leak
Some internal leaks — a worn tap washer or a toilet flapper — are straightforward DIY fixes. Others, particularly underground pipe leaks or anything hidden behind walls, need professional leak detection equipment and repair.
If your meter is still moving after you have isolated the stopcock, or if you can hear water running but cannot locate the source, it is worth calling a plumber sooner rather than later. Underground leaks can undermine foundations and lead to much more costly repairs if left.
When It Becomes an Emergency
Call us straight away on 07725 479493 if:
- Water is visibly pooling in your garden or rising through your floor
- You can hear running water inside a wall or ceiling
- You have lost pressure across the whole house suddenly
- The meter reading is rising rapidly
We cover the TW postcode area 24 hours a day, seven days a week. A calm conversation with our team will help you decide whether you need someone out immediately or whether it can wait until the morning.
The meter test costs nothing and takes half an hour. If it gives you a clean result, you have peace of mind. If it flags a problem, you have caught it early — and that is almost always better than waiting.