How to Report a Leak to Thames Water

Reporting a leak to Thames Water takes a few minutes. What happens afterwards depends on one question, and it is worth settling before you pick up the phone: which side of the property boundary is the water escaping from. If it is theirs, they locate and repair it on their own timescale and at no cost to you. If it is yours, the report starts a clock, and the obligation to fix it within four weeks is yours.

That distinction is the whole of this subject, and it is where most of the misinformation sits. Everything below is taken from Thames Water's own published help pages, because third party sites carry a good deal of out of date material about repair schemes and free replacements that their current pages simply do not say.

Who Is Responsible for Which Pipe

Thames Water's pipe responsibility page sets the boundary out plainly. They own and maintain the water mains and the communication pipe that links your supply pipe to their mains. You own the supply pipe from the boundary of your property into your home, which is usually under private land such as a garden or driveway, and you own every internal pipe, appliance and fitting.

Shared supply pipes, which are common in London

Where a single pipe serves more than one property, Thames Water states that you and your neighbours hold joint responsibility for maintaining the shared part and for any associated costs. In a converted terrace or a Victorian house split into flats this is the normal arrangement rather than the exception, and it is worth establishing before a leak, not during one. A shared pipe also makes location work more valuable, because the point at which the leak sits along the run determines who is contributing to the repair.

Tenants and landlords

Thames Water's position is that repair responsibility rests with the landlord, and that a tenant should notify them promptly and in writing. Writing matters here for the same reason it does anywhere else: the four week clock and any later dispute both turn on the date the leak was reported, and a text or an email is a date while a doorstep conversation is not.

Reporting a Leak in the Street or on a Pavement

This is the easy case. Thames Water invite customers to report leaks they see while out and about, through the report a problem section of their website, and it is the fastest route because it goes straight into their system rather than through a call queue.

What to include so the report is actionable

• The nearest full postal address or a precise description of the location, not just a street name.
• Where exactly on the highway: carriageway, footway, verge, or a specific cover or hydrant.
• Whether water is running, bubbling up or simply keeping an area permanently wet.
• Roughly how long it has been there, if you know.
• Whether it is affecting traffic, pedestrians or a property.
• A photograph, which resolves most ambiguity about location and scale.

What happens after you report it

Thames Water publish their leak repair process as four stages: locating the leak, investigating it so a leakage team can assess what needs fixing and how urgent it is, planning the logistics with councils and other utilities, and then repairing and resurfacing. They say they repair urgent leaks on the mains and pipes that belong to them as soon as they can, and they prioritise on four factors: the amount of water being lost, the effect on customers' water supply, the complexity of the job and the location.

Two things follow from that. No specific timescale is published, so a small pavement weep that is losing little water and affecting nobody can legitimately sit for some time behind larger jobs. And the third stage, coordinating with councils and other utilities, is often the slow one rather than the repair itself, particularly on a busy road. If a reported leak appears to have been forgotten, the useful thing to ask for is the job reference and the current prioritisation, rather than simply reporting it again.

Reporting a Leak on Your Own Property

Report it the same way, but understand what you are starting. Thames Water's arranging leak repair page states that when you have a leak on your property you must fix it within four weeks of finding it, or of them reporting it to you. That is a duty on the property owner, not a service level on the water company.

The four week rule and what happens if it is missed

Their published position is direct: if you do not arrange repair within four weeks, they may serve legal notice under Section 75 of the Water Industry Act 1991, which gives them the power to carry out the repair and charge you for it. There is a second consequence that people miss. A leak repaired under a Section 75 notice is expressly excluded from the leak allowance, so missing the deadline can cost you both the repair charge and the bill adjustment.

What Thames Water Will Not Do for You

This is the part that third party advice most often gets wrong, and it is worth being exact about. Thames Water's own pages do not offer a general free repair or free replacement of a customer's supply pipe. What their arranging leak repair page directs customers to do is check their home buildings insurance policy first, because if it covers emergency plumbing or leaks the insurer may help arrange the repair and cover the cost, and otherwise to engage a leak detection specialist or plumber.

What they do say about choosing a contractor

They recommend using an approved WaterSafe contractor, recognised by water company schemes including APLUS, WaterMark and WIAPS, so that the work meets the required standard and protects drinking water quality. They also state plainly that your contract will be with the approved plumber or contractor and not with Thames Water, and that they cannot give assurance of availability or guarantee the work. In other words, the recommendation is a register, not a referral, and the commercial relationship is entirely yours.

Where help does exist

There is one meaningful exception in their published material. Customers registered on their financial support schemes may be able to get assistance with repair costs. If money is the obstacle, that is the conversation to have with them rather than letting the four week period run out. Our note on who is responsible for a Thames Water leak covers the boundary in more detail, and our guide to an underground supply pipe leak covers the practical side of a buried pipe.

The Leak Allowance and How to Qualify

A leak on your supply pipe registers on your meter, so a long running one produces a bill for water that never reached the house. The leak allowance is the mechanism for adjusting that, and it is conditional rather than automatic.

How the adjustment is calculated is also published: they compare your historic usage over a comparable period against the volume recorded by the meter while the leak was running. That makes your own meter readings valuable evidence, particularly a reading taken before the leak was suspected. Our guide to the Thames Water leak allowance after a high bill works through the application itself.

Proving Whose Leak It Is, and Where That Goes Wrong

Before reporting anything, it is worth doing the test that decides which conversation you are about to have. Close every outlet in the property, including the toilet fill valves and any outside tap, then read the meter, leave it untouched for an hour or more with nothing used, and read it again. Movement means water is being lost downstream of the meter. Our guide to reading your water meter to check for a leak sets out the method and the common errors.

What the meter test cannot tell you

It cannot tell you where the leak is, only that there is one somewhere past the meter. That matters because the meter is usually at or near the boundary, so a positive result covers everything from the boundary box across the garden or driveway and through the whole house. It also cannot distinguish a leak from a passing toilet fill valve, which is the single commonest false positive and accounts for a large share of unexplained meter movement. And it says nothing at all about a leak on Thames Water's side of the meter, which will not register on it, so a wet patch in the front garden with a static meter points at the communication pipe rather than at yours.

Where reports commonly go wrong

• Reporting a wet patch as a street leak when the meter is moving, which sends the wrong team and wastes the four weeks.
• Assuming a dry meter clears the property. A leak below the meter chamber on a shared run can behave ambiguously, and stored systems complicate the reading.
• Repairing before recording anything. Photograph the excavation, the pipe and the failure, because the allowance and any insurance position both depend on evidence you cannot recreate afterwards.
• Treating a verbal report to a landlord or a neighbour as a report. Only something with a date on it counts.
• Waiting for a bill before claiming the allowance. The three month window runs from the repair date, not from the bill.

What to Do, and in What Order

The sequence that keeps every option open is short, and none of it is technical:

• Run the meter test with every outlet closed, and photograph both readings with the time visible.
• If the meter is static and water is surfacing outside, report it as a suspected leak on their side and ask for a job reference.
• If the meter is moving, report it, note the date, and treat the four week period as having started.
• Check your buildings policy for a trace and access clause and for any emergency assistance cover, since Thames Water direct customers to their insurer first.
• Locate the leak before excavating. On a buried supply pipe crossing a garden or drive, the difference between a located repair and an exploratory trench is substantial, and our note on a water leak in a garden or driveway covers how those are narrowed down.
• Keep the invoice, the job number and your meter readings together, and apply for the allowance within three months of the repair.

The one thing not to do is nothing. The four week duty runs whether or not the leak is inconvenient, the water continues to register on the meter throughout, and a Section 75 notice removes both the choice of contractor and the allowance at the same time.