Thames Water Leak Allowance After a Leak: How to Claim Back the Extra Water Cost

Discovering a hidden leak is stressful enough without receiving a water bill that is two or three times its normal size. Thames Water operates a leak allowance scheme that can reduce the portion of your bill caused by an undetected leak — but there are deadlines, evidence requirements and eligibility conditions you need to know about. This guide walks you through the process in plain terms.

This guide is general consumer information. Emergency Plumbers TW repairs leaks and provides written documentation of the fault. Your allowance application is your own claim, submitted directly to Thames Water.

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What Is the Thames Water Leak Allowance?

Thames Water’s leak allowance (sometimes called a “leakage allowance” or “goodwill adjustment”) is a discretionary reduction on your water bill to account for water lost through a leak you were not aware of. It is not a refund of repair costs — it only addresses the inflated water usage charge on your account.

Thames Water decides each case individually. There is no legal entitlement, but the scheme is well established and widely used across the TW postcode area.

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Am I Eligible?

Thames Water’s general eligibility criteria include:

• The leak was on your side of the boundary stop tap (i.e. on your property, not in the public main).
• The leak was undetected — not a dripping tap you knew about.
• You have had the leak repaired by a qualified plumber.
• You apply within 90 days of the repair being completed.
• You have not claimed a leak allowance in the previous 24 months at the same address.

Criteria can change, so always check the current terms on the Thames Water website before applying.

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The Four Key Steps

1. Get the Leak Repaired First

Thames Water will not consider an allowance while a leak is still active. The repair must be completed before you apply. Keep the plumber’s invoice — it is the primary piece of evidence you will submit.

Your invoice should clearly show:

• The date of the repair
• The address
• A description of the fault (e.g. “burst 15 mm supply pipe under kitchen floor”)
• The plumber’s name and, ideally, their company details

Repair within four weeks of discovering the leak wherever possible. A long delay between discovery and repair can affect how sympathetically Thames Water views the application.

2. Take Two Meter Readings at Least 14 Days Apart

After the repair is done, Thames Water typically wants to see that water consumption has returned to normal. Take a meter reading on the day of the repair and another at least 14 days later. Note the date and time of each reading and photograph the meter display.

This pair of readings demonstrates that the excessive usage has stopped and was caused by the leak, not by something else.

3. Gather Your Supporting Evidence

Before you contact Thames Water, have the following ready:

• Plumber’s invoice (dated, itemised, signed)
• Two post-repair meter readings with dates
• Photographs of the leak location, the damage, and any moisture readings if your plumber took them
• A copy of the bill you want adjusted
• Your Thames Water account number

If your plumber provided a written report describing the cause of the leak, include that too. The more clearly you can show that the excess water was lost through an undetected fault, the stronger your application.

4. Apply Within 90 Days of the Repair

Submit your application directly to Thames Water — by phone, online form, or in writing. The 90-day window runs from the date of repair, not from the date the high bill arrived. Missing this deadline is the most common reason applications are declined, so act promptly once the repair is done.

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What the Allowance Covers — and What It Does Not

What it can reduce	What it does not cover
The inflated water usage on your bill	The cost of the repair itself
Sewerage charges linked to the excess usage (sometimes)	Damage to floors, walls or belongings
Standing charges in some cases	Any insurance excess

Repair costs and property damage are separate matters between you and your home insurer. Thames Water’s scheme deals only with the water bill.

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A Note on Meter vs. Unmeasured Accounts

If you are on a metered supply, the allowance is straightforward: Thames Water can see the spike in your usage data. If you are on an unmeasured (rateable value) account, the process is different — contact Thames Water directly to discuss your options.

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How Emergency Plumbers TW Can Help

Our role is simple: find the leak, fix it, and give you a clear written record of what we found and what we did. That written record — cause of fault, photographs, moisture readings, scope of work — belongs to you and forms the backbone of your Thames Water application.

We cover the TW postcode area around the clock, including Twickenham, Richmond, Teddington, Isleworth, Hounslow, Feltham and Staines.

If you have a leak right now, the most important thing is to stop it quickly. The sooner the repair is done, the sooner the excess usage stops — and the stronger your allowance application will be.

Call us any time on 07725 479493. We will get to you, sort the leak, and make sure you have everything you need to take the next step with Thames Water yourself.