Thames Water leak allowance: who gets one, and how to claim

What the allowance actually is

Your meter records every litre that passes it, including the litres that went into the ground. The leak allowance is Thames Water crediting your account for the difference between what you would normally have used and what the meter recorded while the leak was running. It is an adjustment to a bill, not a payment for the repair and not compensation for damage.

Two things follow from that. First, it only exists if you are on a meter. An unmetered bill is based on rateable value, so a leak does not change it and there is nothing to credit back. Second, where Thames Water bills you for wastewater as well, the credit is applied to both the water and the wastewater side. If a different company handles your wastewater, Thames Water tells them so they can apply their own adjustment.

It is also discretionary. Thames Water's published wording is that they "may" cover the cost of the lost water, and their code of practice says claims are considered individually. Meeting every criterion puts you in a strong position. It does not entitle you to a credit.

The two deadlines that decide most claims

Almost everything turns on dates, and there are two.

• Four weeks to fix it. The leak has to be repaired within four weeks of Thames Water first notifying you, or of the leak otherwise being identified. That clock starts on the letter or the call, not on the day you got round to reading it.
• Three months to claim. The allowance has to be claimed within three months of the repair date. Thames Water are explicit that this applies even if no bill has arrived yet — waiting for the bill before you claim is one of the commonest ways people time themselves out.

The four-week window is also the window before Thames Water can start using statutory powers. If nothing is done, they can serve a formal notice and then an enforcement notice, repair the pipe themselves under the Water Industry Act 1991, charge you for the work, and decline to consider you for a full allowance. A leak repaired under a Section 75 notice is excluded from the allowance outright.

What they ask you to prove

Thames Water have to be able to confirm the leak was actually fixed. There are only two accepted routes:

• A plumber's details and invoice, if a private contractor did the work.
• A Thames Water job number, if they did the repair themselves.

Their code of practice also refers to insurance documents as proof of repair where a third party fixed the leak for you. What matters is that the paperwork names the property, names who did the work, and makes clear what was repaired and when. An invoice that reads "plumbing works" with no date and no address gives the assessor nothing to tie to your meter readings. If you are getting a repair done and you intend to claim, say so to whoever is doing it — a compliant invoice costs nothing extra at the time and is very hard to reconstruct afterwards. We cover what a good one contains in more detail on the evidence you need for a leak allowance claim.

Where the form is, and what it asks

There are two submissions, in order, and people frequently do only the first. You tell Thames Water the leak is fixed using their leak fixed form. Then you complete the leak allowance form, which is linked from their leak allowance page under Help and advice. The allowance form is the one that actually starts the claim.

Before you open it, have these to hand:

• Your account number and the supply address.
• The date the leak was first identified or notified to you, and the date it was repaired.
• The repairer's name and invoice, or the Thames Water job number.
• Meter readings. Thames Water compare readings from before, during and after the leak. Readings are the part of the form most often left blank, and they are the part the calculation depends on. If you are not sure where your meter is or how to read it, start here.
• A plain description of the leak: where it was, how it showed itself, how long it had likely been running.

Fill in every section. Their own guidance is that the more they know about the leak, the more accurately and quickly they can work out the allowance. Your direct debit and billing date carry on as normal while the claim is assessed — the claim does not pause the account.

Online form or the PDF download

Most people search for the leak allowance form expecting a single download. There are two versions. The online form is reached from the Thames Water leak allowance page. There is also a published paper form as a PDF, which you can print, complete and return. The paper version is useful for one reason even if you apply online: it shows you every field in advance, so you can collect the dates and readings before you start.

Two details in the PDF catch people out:

• It asks for two meter readings taken after the repair, at least 14 days apart. That is how Thames Water see your normal use once the leak has stopped. If you submit the day after the repair, you will not have the second reading yet, so plan the timing around it rather than waiting until the last week of the claim window.
• The paper form states the claim deadline as 90 days, while the web page says three months. The two are not always the same length. Work to the shorter one.

Beware of third-party sites offering to "submit your leak allowance form" for a fee. The application is free and goes directly to Thames Water. Our step-by-step guide to filling in the leak allowance form walks through each section, and how the leak allowance is calculated shows how to check the credit once it arrives.

How the credit is worked out

If the property has its own supply and its own meter, the sum is straightforward. Thames Water compare your consumption over a comparable earlier period against what the meter recorded during the leak, price the difference, and credit that amount. Where there is no history to compare against — a new occupier, a newly fitted meter — they substitute typical consumption for a household of that size and occupancy, and they can adjust afterwards if your real usage turns out to be very different.

Their code of practice allows backdating to when the leak started, to a maximum of two years. That matters for the slow underground losses that never surface: a weeping supply pipe can run for a year before anyone notices the bill has drifted.

If the adjusted bill still does not look right to you, say so. They will review the allowance and give you a decision. If the claim is turned down altogether, what to do when a leak allowance is rejected sets out how to answer the stated reason rather than resubmitting the same form.

What usually gets a claim refused

These are the exclusions Thames Water publish, in the order they bite:

• The repair took longer than four weeks from notification, without Thames Water having agreed otherwise.
• The claim came in more than three months after the repair date.
• No usable proof of repair — no invoice, no plumber's details, no job number.
• The leak was fixed under Section 75, or you were charged for work Thames Water carried out under their statutory powers.
• You were already told the supply pipe needed replacing — including if that advice went to a previous owner — and it was never done.
• The leak was caused by your negligence, or you knew, or should have known, there was a leak and did not repair it.
• It was an internal leak beyond your internal stopcock. Thames Water say they do not usually allow for these, except where in their opinion you could not reasonably have known about it. A dripping overflow in a loft you never go into is a different case from a running toilet on the ground floor.

One distinction worth knowing: for internal pipework, the allowance is available on one occasion only. For leaks on the water supply pipe itself, you can claim as many times as you need. So if you have had a kitchen leak credited before, a later supply pipe leak is still claimable. Where the water company draws the line between its own leakage and yours is explained in what the water industry counts as a leak.

If you rent

Tell your landlord immediately and check the tenancy agreement for who is responsible for repairs. If you are billed for the water, you are the one who claims. Thames Water's leakage terms say they will still consider a full allowance for a tenant who told the landlord and the landlord failed to get it repaired inside the four weeks, provided the tenant cooperated with getting it fixed quickly. Keep the messages that show when you reported it.

Our part in this, and what it is not

We repair the leak. The allowance is between you and Thames Water, and we have no influence on their decision — anyone who tells you they can guarantee you an allowance is selling you something. What we can do is make sure the claim is not lost on paperwork: the invoice names the property, states the date, describes what was found and what was repaired, and is issued the same week.

Most allowance-relevant leaks are on the private section of the supply pipe between the boundary stopcock and the house, which is your liability to repair. That is a mains supply pipe repair. Work is charged at our hourly rate, agreed before we attend, with no call-out fee; if we do not find the leak you do not pay for the time we spent looking. The rate is on the pricing page.

And to be clear about what the allowance is not: it does not cover the repair bill, it does not cover damage to your floors or your neighbour's ceiling, and it does not cover a leak on Thames Water's side of the boundary — that one is their repair and their water, and there is nothing to claim.