Water Meter Running With No Taps On

First, make sure it is your meter and it really is moving

Before you look for a leak, check the meter serial number against the one on your bill. In terraced streets and blocks of flats, meters sit side by side and it is easy to read a neighbour’s. Then look at the flow indicator, the small star or cog wheel on the dial. If that is turning, water is passing. If only the last red digit has changed since yesterday, someone in the house may simply have used water overnight.

Size it quickly by watching the litres digit for one full minute. One litre a minute is 60 litres an hour and over 1,400 litres a day, which is a serious leak and will show on your bill. A flow indicator that turns slowly but never moves the litres digit in a minute is a drip, usually a cistern or a tap. Our guide on how to read a water meter explains the digits and the longer half-hour test.

Things in the house that use water on their own

Go round the house in this order. Each check takes a minute or two, and the first four account for most running meters.

• Toilets: listen for a faint hiss and look for a ripple at the back of the pan. A worn fill valve or flush valve seal lets water run through continuously
• Cistern overflows: look outside for a small pipe dripping from the wall below a bathroom
• Loft cold water tank: if the float valve sticks, the tank fills to its overflow and water runs out of a pipe at the eaves
• Combi or system boiler: a filling loop left slightly open lets mains water into the heating, pressure climbs, and the relief valve dumps it through a copper pipe outside
• Unvented cylinder: water running into the tundish, the small open funnel on the discharge pipe near the cylinder, means a relief valve is letting by
• Water softener regenerating, a fridge with a plumbed ice maker, or an outside tap with a hose left on

If the tundish on an unvented cylinder is passing hot water, turn off the boiler or immersion heater that heats the cylinder and get it looked at. That valve is a safety device and continuous hot discharge is not normal.

The stopcock test: inside or outside the house?

Once you have ruled out the obvious, close your internal stopcock and watch the flow indicator again. This splits the problem in two.

If the indicator stops, the water is going somewhere inside the house. Work through the list above again with a torch, then look for damp patches on ceilings under bathrooms, swollen skirting boards, warm spots on a solid floor (a hot pipe leaking under screed) and water under the kitchen units. A heating system that needs topping up every few days with no visible leak points the same way. The page on hidden leak signs lists what to look for room by room.

If the indicator keeps turning with the stopcock closed, water is escaping between the meter and the house. That is the supply pipe, usually buried under the front garden, path or driveway. You will often see nothing at all, especially on clay soil, which is why a meter is often the first thing to give it away. Wet ground that never dries or a patch of greener grass on the pipe route are clues; if the wet patch is out in the pavement instead, Thames Water takes leak reports for its side of the boundary. A stopcock that does not fully close gives the same result, so confirm the valve actually shuts by opening the kitchen cold tap; it should run dry within a few seconds.

Who fixes it, and what it typically costs

Everything on your side of the boundary is normally the owner’s responsibility, including the supply pipe from the outside stop tap or meter chamber to the house. The water company is responsible for the pipe from the main to the boundary. If the meter sits in the pavement, the boundary still decides it: a leak on the length inside your property line is yours, and one out in the pavement is normally the water company’s to fix. Our guide to mains water pipe responsibility sets out where the line falls.

Inside the house, most causes are small jobs. A replacement cistern fill valve or flush valve seal is a common repair, as is closing and replacing a passing filling loop, freeing a stuck float valve in a loft tank, or replacing a relief valve. Market prices for these generally sit in the low hundreds of pounds including the part.

A supply pipe leak is bigger. The leak has to be found, normally by listening equipment or tracer gas, then dug out and repaired, or the whole run replaced. As a rough market guide, a single excavation and repair often costs a few hundred pounds, and a new supply pipe laid by moling under the garden commonly runs well past £1,000, more where hard landscaping has to come up. The leak repair service covers both, starting with a £60 call-out, and the repair price is agreed with you on site before any work starts.

Claiming back the wasted water

Most water companies offer a leak allowance, a credit for water lost through a leak rather than used, provided you fix it promptly and can show the repair. It is aimed mainly at hidden leaks such as the underground supply pipe; faults you could have seen inside the house, like a running toilet or a dripping tap slowly wasting water, are often excluded, and some companies allow only one claim. Read your company’s terms before assuming you are covered, keep the invoice, and take meter readings before and after the repair. Our page on water leak costs and your bill goes through the process.

When a running meter cannot wait

Treat it as urgent if the litres digit moves visibly while you watch, if you can hear water running in a wall or under the floor, if a ceiling is staining, or if the flow is on the supply pipe near the house walls, where it can wash out soil under foundations. In those cases close the stopcock and leave it shut except when you need water. If the stopcock will not close, or the leak is before it, the only shut-off is the outside stop tap; see the external stopcock guide.

A slow toilet leak can wait until the morning. Turn off the small isolation valve on the cistern supply after each flush until it is fixed.