Home › Guides · Updated 21 October 2026

How to use your water meter to find a hidden leak

A step-by-step water meter leak test: how to read the dials, how to tell whether a leak is inside your home or on the underground supply pipe, who pays for the repair and how to claim a leakage allowance.

A bill that suddenly jumps, a meter that never stops ticking, or a patch of lawn that stays wet in dry weather can all point to a hidden leak. If you have a water meter, it is the best free leak detector you own. This guide shows how to run the test that the Consumer Council for Water (CCW) recommends, how to narrow down where the leak is, and what happens next.

Step 1: rule out the obvious

Before testing the meter, look for visible leaks. CCW's self-help leak test suggests checking:

• overflow pipes from cold water tanks and toilet cisterns, often visible as a drip outside;
• taps and appliances that drip or don't turn off properly;
• outside taps left running.

A toilet that keeps running into the pan is one of the most common silent wasters. Our guide to fixing a toilet that keeps running walks through it, and a dripping tap is usually a quick fix too.

Step 2: find and read your meter

Meters may be inside, often under the kitchen sink near the stop tap, or outside in a chamber under a small cover in the pavement or driveway. If you can't find it, your water company can tell you where it is.

If your meter is outside, CCW advises only checking it if it is safe to do so, and warns not to try to lift a heavy metal cover. Lift a light cover with a screwdriver blade and remove any polystyrene insulation to see the meter face, which may be some way below ground.

CCW explains that meters record in cubic metres. Black or white numbers show whole cubic metres; red numbers or dials show fractions. The red dials are the ones that reveal small leaks, because they move first.

Step 3: the overnight test

CCW's steps for checking for a leak are simple:

1. Turn off all taps and appliances that use water: washing machine, dishwasher, combi boiler hot water, garden hoses and any water softener regeneration.
2. Take a photo or write down the meter reading, including the red digits.
3. Wait a few hours, or overnight, without using any water. Don't flush the toilet.
4. Take a second reading.
5. If the second reading is higher and you're sure no water was used, you may have a leak.

Some systems refill quietly after you stop using water, such as a toilet cistern or a cold water storage tank in the loft. Wait at least half an hour after last using water before taking the first reading so they have finished filling.

Step 4: inside or outside?

If the meter moved, the next step is to work out where the leak is. The CCW leak test explains:

• If your meter is inside your home, the leak must also be inside the premises, after the meter.
• If your meter is outside, turn off your internal stop tap and repeat the test. If the meter still moves, there could be a leak between the meter and the internal stop tap: the underground supply pipe. If it stops, the leak is inside the property after the stop tap.

CCW's leak test notes that if your stop tap is missing or won't work, you'll need one fitted before you can carry out this step. If you're not sure where yours is, see our guide to finding and turning off your stopcock.

Finding a leak inside the house

Work through the house methodically with the meter as your guide:

• Check the toilet cistern overflow and listen for a hiss. A few drops of food colouring in the cistern that show up in the pan without flushing indicate a leaking flush valve.
• Look under sinks, behind the washing machine and dishwasher, and around the boiler.
• Check the loft tank and its float valve if you have one.
• Look for damp patches, stained ceilings, lifting floors or a musty smell, which can point to a pipe leak under the floor or in a wall.
• If you can isolate parts of the system, such as with service valves on individual taps and appliances, close them one at a time and watch the red dial.

For hidden pipe leaks, a plumber with acoustic or thermal detection equipment may be needed. CCW suggests the WaterSafe scheme as a way of finding trusted plumbers in your area.

Who pays to fix it?

Responsibility depends on where the leak is. According to Ofwat, the water company is responsible for the water main and the communication pipe up to the property boundary, while the supply pipe from the boundary to the first stop tap or fitting inside the property is normally the property owner's. CCW adds that the water company is also responsible for the meter, if there is one, and for the external stop tap usually found in the footpath.

So a leak inside your home, or on the supply pipe in your garden, is normally yours to repair. Ofwat says you should contact your water company to find out if it offers help with subsidised or free repairs, and that each company must have a code of practice on household supply pipe leaks. CCW says some companies offer one-off assistance with locating and repairing a supply pipe leak, though the conditions vary.

Our guide to who is responsible for which water pipes explains the boundaries in more detail, including shared supply pipes.

Claiming a leakage allowance

If a leak pushed up a metered bill, you may not have to pay for all of the lost water. Ofwat says that if your bill was abnormally high because of a leak that has since been repaired, you may be able to claim an allowance for the cost of water lost. CCW notes that after a repair your company should offer a leakage allowance, and that it is usually a one-off.

Be aware that allowances generally depend on the leak being hidden. CCW's leak test notes that where a leak is visible, such as a running tap or overflow, a water retailer will usually not grant an allowance. Keep the plumber's invoice and before-and-after meter readings as evidence. CCW also suggests checking whether your home insurance covers the cost of lost metered water.

Make it a habit

• Note your meter reading when you go away and again when you return.
• Repeat the overnight test every few months, and whenever a bill looks high.
• Insulate exposed pipes before winter; our guide to frozen and burst pipes explains how.

Sources and further reading

• CCW: Why is my water bill high?
• CCW: Self-help leak test (PDF)
• CCW: What can I do if I suspect there is a leak on my private water supply?
• CCW: Who is responsible for my water pipes?
• Ofwat: Responsibility for pipes and pumping stations
• WaterSafe: find an approved plumber

Facts and links checked on 21 October 2026. Spotted an error? Tell us and we will correct it.