Underground water leak detection on your supply pipe
Underground water leak detection locates a leak on the supply pipe buried between the property boundary and the house, the pipe the owner is responsible for under every main water company in the region, and marks the spot to dig on the surface above it. West Country Leak Detection traces these leaks for homes across South West England.
Who owns the buried pipe between the street and your house?
The buried supply pipe running from the street boundary to the house is the homeowner's to look after in every main water company area of the South West, while the water company is responsible for the main and for the communication pipe that links the main to it.
Two terms carry the whole question. The communication pipe runs from the water main to the boundary and belongs to the water company; the supply pipe is the part of the service pipe the company does not own, under regulation 1 of the Water Supply (Water Fittings) Regulations 1999. Thames Water, for example, looks after the water mains and the communication pipe joining each supply pipe to them. Each company words the boundary its own way.
| Water company | Where the company's pipe ends | The owner's supply pipe |
|---|---|---|
| South West Water | At the boundary of the street the main is laid in, which in most cases is the property boundary | From that boundary to the internal stop tap, usually under the kitchen sink |
| Bournemouth Water | The same wording as South West Water, under its own name | From the boundary of the street the main is laid in to the internal stop tap |
| Bristol Water | The property boundary | Everything inside the property boundary, the owner's or the landlord's to locate and repair |
| Wessex Water | Generally the boundary of the street and the property, with external stop taps and meters | From its communication pipe to the house, even where the owner does not own the land |
| Severn Trent | The edge of the highway, with the underground stop tap most properties have there | The customer service pipe, from that stop tap into the house |
| Thames Water | The communication pipe joining the supply pipe to its mains | From the property boundary into the home, usually under a garden or drive |
Your supplier depends on your postcode, and several areas are split between companies. You can check which water company supplies your area, or use the postcode checker Wessex Water points to on its find your water supplier page.
When one supply pipe serves more than one home
A supply pipe shared by several properties is the joint responsibility of every owner connected to it, the Consumer Council for Water says, and South West Water, Wessex Water and Thames Water all treat the shared length that way, with each branch belonging to the home it serves.
When the supply pipe is long or the main is far away
A house set back from the street has a very long supply pipe, and South West Water says the owner is responsible for all of it, even where it passes through other people's property. Where the main is not in the road outside, South West Water extends the boundary of the street by 18 metres from the centre of the road. The meter is no guide either: Thames Water's household code says its position does not determine who owns the pipe.
Tenants report a leak to the landlord. Wessex Water tells tenants to let the landlord know as soon as possible and check the tenancy agreement, and Thames Water puts the duty to fix leaks on the landlord.
How does a water meter reveal a leak on the supply pipe?
A water meter points to a leak on the supply pipe when its dial keeps moving with every tap off and the internal stop tap closed: Wessex Water says the leak is then most likely outside the property, and Bristol Water says it could be between the meter and the internal stop tap.
Stop using water and watch the meter dial
Turn off every tap and water-using appliance. Wessex Water says a dial still turning while no water is used means there is most likely a leak.
Close the internal stop tap
Shutting the internal stop tap cuts the house off from the supply pipe, so water still registering on the meter is most likely escaping before it reaches the home.
Read the meter dial again after the time your company gives
South West Water's leaks page asks for two readings an hour apart, every dial included, and WaterSafe also says readings one hour apart. A dial that has stopped points back inside the house.
Timings differ by company. South West Water's code of practice says to turn appliances off for a couple of hours, and warns that a storage tank filling up can move the dial without any leak.
Swindon homes on Thames Water's smart meters send their readings to Thames Water automatically, and once a meter is fitted, Thames Water checks remotely for leaks before activating it.
What does a sudden rise in a metered water bill mean?
A sudden rise in a metered water bill can mean water is leaking after the meter, and once the leak is repaired each of the region's main water companies offers a leak allowance, on conditions that start with repairing it within a set time.
Wessex Water lists an unexplained increase in your bill among the signs of a leak, and WaterSafe lists an unusually high water bill among the signs of a leaking supply pipe. If the bill was abnormally high because of a leak that has since been repaired, Ofwat says you may be able to claim an allowance for the water lost.
| Water company | Repair the leak within | Other conditions |
|---|---|---|
| South West Water | 30 days of its contact with you about the leak | Supply pipe leaks; no more than two allowances at the same property |
| Bournemouth Water | No single figure: its own pages disagree, so read its leak allowance page | Passes details to the sewerage company for a similar adjustment |
| Bristol Water | 21 days of being made aware of it | Reduces the bill once the repair is made |
| Wessex Water | 28 days under a Private Leakage Notification | A meter, a claim within six months, readings straight after the repair and two weeks later |
| Severn Trent | Its 28-day period | Once only, supply pipe leaks only, two readings two weeks apart after the fix |
| Thames Water | Four weeks | Proof of repair, and a claim no more than three months after the repair |
Ask the sewerage company as well. The Consumer Council for Water points out that leaked water often drains into the ground and never reaches the sewer, so an allowance on the sewerage charge is worth asking for too.
How is a leak on a buried supply pipe pinpointed?
A leak on a buried supply pipe is pinpointed by listening along the pipe's route with ground microphones, or, where the leak is quiet, by filling the drained pipe with tracer gas and finding where it rises through the surface.
| Method | How it works | Its limit |
|---|---|---|
| Acoustic listening | Acoustic listening follows the noise a leak makes on a pipe under pressure, using a listening stick against the pipe or a fitting, or a ground microphone set down on the surface above it, and the leak sits close to the spot where that noise peaks. | With no pressure in the pipe, or no sound from the leak, there is nothing to hear, and Sewerin's advice in that case is tracer gas. |
| Tracer gas | For tracer gas testing the pipe is drained, sealed and filled from a cylinder with a mixture of 95% nitrogen and 5% hydrogen, then a hydrogen detector is swept across the surface until it finds where the gas coming up from the leak is strongest. | How quickly the gas surfaces depends a great deal on the ground above the pipe, INFICON says, so no time is ever promised. |
Sewerin's acoustic method touches a listening stick to the pipe or a fitting at several points, takes the stretch between the two loudest as the rough position, then pins the exact spot with a ground microphone. Hydrogen is the smallest and lightest molecule there is, and in Sewerin's account it climbs quickly to the surface through concrete, tarmac, block paving or grass.
The aim is one marked place to dig, located before plaster or paving is broken. How long the gas takes to surface depends on the ground, INFICON says, so no time is ever promised.
What do South West water companies offer when the leak is on your side?
South West water companies offer help on their own terms: South West Water, Bournemouth Water and Bristol Water each give up to half an hour of free leak detection, Thames Water may fix a supply pipe leak for free in some cases, and each company sets its own conditions.
| Water company | What it offers | Conditions and its own page |
|---|---|---|
| South West Water | Up to half an hour of free leak detection with advice, a contribution once the repair is confirmed, and a subsidy towards replacing the leaking supply pipe within 30 days | Homeowners only, one contribution while you own the property; South West Water's help page |
| Bournemouth Water | Up to half an hour of free leak detection with advice, and contributions towards a repair or replacement | Amounts and terms differ across its own pages; Bournemouth Water's help page |
| Bristol Water | Up to half an hour of free leak detection with advice, a subsidy once a repair is confirmed, and a larger subsidy for replacing the supply pipe within 21 days | One payment per leaking pipe, receipts or invoices needed; Bristol Water's help page |
| Wessex Water | Confirming where the leak is if you are unsure, advice on next steps, and guidance through the leak allowance | Contact your insurer right away; Wessex Water on leaks outside your property |
| Severn Trent | A free repair under its scheme for a leak it discovers while installing a meter | Subject to the scheme's terms; Severn Trent on your water supply |
| Thames Water | It may be able to fix a supply pipe leak for free when no insurance or home emergency cover pays and you cannot pay a professional | At its discretion, with limits on pipe length and size; Thames Water leak fix terms |
Inside the home, South West Water's LeakBot page says its customers get leak location and repair visits from LeakBot's plumbers at no cost to them; read the terms on South West Water's LeakBot page.
Every one of these schemes is the water company's own. West Country Leak Detection is a separate service, and each scheme's conditions and time limits belong to the company that runs it.
What happens after the supply pipe leak is marked?
After the supply pipe leak is marked, the owner arranges the dig and the repair within the water company's time limit, keeps the invoice for any contribution or allowance, and reads the meter afterwards as the company asks.
- Repair within the time allowed: South West Water's leakage notice sets anything from 10 to 30 days, Bournemouth Water usually allows 28 days, Wessex Water 28 days from a Private Leakage Notification, Severn Trent a 28-day period and Thames Water four weeks once a leak is confirmed.
- Choose who repairs it: Wessex Water recommends a member of an Approved Contractors' Scheme, such as the WaterSafe Register.
- Read the meter after the repair: Wessex Water asks for readings straight after the repair and again two weeks later.
An older pipe may be lead. South West Water says lead was often used before the 1970s, for the supply pipe or inside the home, and Bristol Water says a home built before 1970 could have lead pipes; replacing the supply pipe on your side is the owner's job in both companies' areas.
If your insurer is paying for the access, ask how trace and access cover for the dig applies to your policy before the dig starts.
Which other leaks can be traced at the same property?
Leaks on the household water pipes indoors and on the central heating can be traced at the same property, as can a leak an insurer needs traced for a claim.
- A meter that stops once the internal stop tap is closed sends the search indoors, to water leak detection inside the house.
- A boiler gauge that keeps falling is a separate circuit, traced by central heating leak detection.
- A claim on home insurance is covered under trace and access when your insurer needs the leak found.
Each of them is introduced under leak detection across the South West.