What smart water meter leak detection can tell you
A constant flow alert means your smart water meter has logged water passing through it in every reading over a stretch of time, usually overnight, when use would normally drop to nothing. It does not say where the water is going. That is the limit of smart water meter leak detection: the meter spots the pattern, and finding the cause happens at the property, starting with checks you can make yourself.
Smart meters record use through the day and night and send the readings on without anyone calling round, so a flow that never stops at 3am stands out in a way an occasional manual reading never could. The warning may arrive as a letter, an email, a text or a note on your online account. However it arrives, it means something in or around the house is using or losing water, and an hour of simple checks can narrow it down a long way.
Ordinary causes to rule out first
Often the cause is a fitting indoors that is quietly passing water. Work through the likely ones before you assume the worst. To check a toilet, wipe the back of the pan dry with tissue and look again after 20 minutes: a fresh damp line means the cistern is letting water through. Or tint the cistern water with a little food colouring and wait. Colour reaching the pan without a flush tells you the same thing.
If you can see your readings hour by hour, the shape of the overnight figures is a strong clue. A flat line at the same rate from midnight to morning points to water escaping all the time. Regular small steps suggest something that fills and stops, such as a cistern topping itself up as it leaks. One long block at the same time each night is often a softener or a watering timer.
A toilet cistern trickling into the pan, often too quietly to hear
A water softener cleaning itself in the small hours
A loft tank float valve that never quite shuts
An outside tap, a hose or a garden watering timer
A plumbed fridge or ice maker, or a dripping tap
Water running through the tundish, the open funnel by a hot water cylinder
Checking the meter yourself
Most meters live in a little chamber with a lid, set into the footpath outside or near the edge of the front garden, and some are fitted indoors, often below the kitchen sink. If the meter is hard to reach or to read, the readings on your water account do the same job, as long as they are recent.
Turn off every tap, appliance and timer, note the reading, wait half an hour and note it again. If the figure has gone up, shut the stop tap indoors and do the same again. If the count then stops, the water is going somewhere inside the house. If a boundary meter keeps counting, suspect the buried pipe between the two. If the stop tap will not turn by hand, leave it and tell us: forcing an old one can break it, and we need it working to test.
A few litres a day or a few litres an hour
The size of the flow says a lot about what to do next. A leak of 1 litre an hour adds up to 24 litres a day and close to 9 cubic metres in a year. At 5 litres an hour it is 120 litres a day, or about 44 cubic metres a year, all of it paid for through the meter whether anyone sees it or not. A few litres a day is often a fitting: a tap washer, a cistern valve or a float valve that sticks.
A few litres an hour, steady through the night, can be a cistern passing freely or a small hole or joint on a buried pipe. Tens of litres an hour may show as a line of greener or soggier grass, a damp verge or weaker taps, though in sandy or gravelly soil a leak that size can soak away and leave no mark. The slowest leaks on buried pipes are the hardest to trace, because a pipe losing a litre or two an hour makes very little sound.
No find, no fee on home water leaks covers one leak on a water main up to 30 m or the hot and cold supply pipes, at least half a litre a minute, where we also carry out the access and repair. That threshold works out at 30 litres an hour, so a leak of a few litres an hour falls below it, and a visit for a leak that size is charged at the agreed price whatever we find. Full conditions are on our terms page.
If the flow is on the supply pipe
When the meter is at the boundary and keeps counting with the stop tap shut, the water is most likely leaving the supply pipe between the two. The water company's responsibility usually ends at the boundary or at the meter, and the stretch running on into the house normally belongs to the owner. Ask your water company about its leak policy before anyone digs: some reduce the bill once a repair is done, and the details are theirs to explain.
A ground microphone, moved a step at a time over the route of the pipe, picks up the noise of water squeezing out under mains pressure, and the loudest point is where we look hardest. Plastic pipe and slow leaks can be quiet, so tracer gas, a hydrogen and nitrogen mix, may be put into the pipe and picked up where it rises to the surface. We want two different tests pointing at one patch of ground before we mark and photograph it, so the dig happens in one place.
What we need to know when you call
One of our first questions is how far it is from your meter to the stop tap indoors. A few metres of pipe under a front lawn is a very different job from a long run under a drive and a yard, or a meter on a verge at the end of a farm track. The price is fixed before you book and covers a set length of visit, a half day or a full one, so the more you tell us, the better we can judge which yours needs.
The flow figure on the alert or your account, in litres an hour
Whether the meter stops when the internal stop tap is shut
Where the meter is, and roughly how far it is from the stop tap
What covers the pipe: lawn, block paving, concrete or gravel
Whether you share the supply with a neighbour
Whether the home is yours, let to a tenant or standing empty
Your insurer and the water company
Check your home insurance before you book. A trace and access section, if your policy has one, exists for the job of finding a concealed leak and reaching it, and it is worth asking whether the insurer needs to approve the visit before it goes ahead. The written report we send covers the location, methods, readings and photographs. It follows once the bill has been settled, and whether to pay a claim is the insurer's call. Keep a copy for the water company too.