How far back will Thames backdate the rebate?

Six years, which Thames spells out as the current financial year plus a further five, where you can provide evidence. No rule forces this. The regulator leaves the length of any refund to each company, so the answer is Thames’ policy rather than your entitlement.

Does it cost anything to apply to Thames?

No. Applying is free. A drainage survey costs a few hundred pounds and is almost never needed, because Thames checks its own records first and will look at the property itself if it is unsure.

What if Thames turns me down?

Complain to Thames first and let it run through both stages. If that gets nowhere, the Consumer Council for Water handles complaints for free. For a binding decision the route since 14 May 2026 is the Dispute Resolution Ombudsman, which took over dispute resolution for the water industry when the previous service was stopped on 24 April 2026.

Rainwater drainage · Thames

The Thames Water surface water drainage rebate

Thames Water bills you for taking rain off your roof and driveway into the public sewer. If your rainwater goes into a soakaway, a ditch or a stream instead, you are paying for a service you do not get, and Thames will stop charging you for it.

Go to the Thames rebate page

What you stop paying

£47.70

a year, metered or not

Backdated

6 years

rolling window from the date you apply

Cost to apply

Nothing

no firm needs to be involved

What Thames charges in 2026-27

£47.70 a year. How it is worked out: flat rebate, stated directly for metered and unmetered households.

The sewer map is the sticking point here more than the photographs. If Thames has a surface water sewer recorded near your property, expect to be asked to show where your rainwater goes instead.

How far back Thames will refund

Six years, which Thames spells out as the current financial year plus a further five, where you can provide evidence.

Nothing obliges Thames to refund anything beyond the current charging year. The regulator leaves the decision to each company, so what you read above is a policy rather than a right, and it can change. The one thing the regulator does expect is that a company which already knew your home was not connected should refund from the point it knew.

What Thames asks you to send

Thames asks you to prove it to their satisfaction, and checks its own sewer maps as well. It will refuse where its maps show a surface water sewer near the property.

Before you spend money on a drainage survey, apply and see what happens. Companies check their own sewer records first, and several will send someone to look at the property at their own cost. A survey costs a few hundred pounds, which is several years of the charge itself.

How to claim it from Thames

Walk round the outside and follow each downpipe. One that ends at ground level near the wall is a soakaway. One that runs across the garden into a manhole is a sewer connection
Check the drainage plan from when you bought the place, if you have one
Open the Thames rebate page and start the application
Send exactly what they ask for, and nothing extra. The section above has their own wording
Ask in writing for the refund to be backdated as well as the charge stopped. Companies sometimes do only the second half
Keep a copy of the date you applied, because the backdating is measured from it

Apply to Thames

If Thames says no

Run the complaint through both of Thames’ own stages first. If it is still unresolved, the Consumer Council for Water will take it up for free. That step gives you a free, independent review rather than a binding ruling.

For a decision the company has to follow, the route changed this year. The consumer body was told to stop running its own dispute service on 24 April 2026, and on 14 May 2026 the industry appointed the Dispute Resolution Ombudsman in its place. That service is free, and it is an interim arrangement until the government sets up a statutory water ombudsman.

Common questions

How much is the Thames Water surface water drainage charge?: £47.70 a year, read from Thames Water’s own household charges scheme for 2026-27. How it is worked out: flat rebate, stated directly for metered and unmetered households. That is the amount you stop paying if your home turns out not to drain to a public sewer.
How far back will Thames backdate the rebate?: Six years, which Thames spells out as the current financial year plus a further five, where you can provide evidence. No rule forces this. The regulator leaves the length of any refund to each company, so the answer is Thames’ policy rather than your entitlement.
What evidence does Thames want?: Thames asks you to prove it to their satisfaction, and checks its own sewer maps as well. It will refuse where its maps show a surface water sewer near the property.
Does it cost anything to apply to Thames?: No. Applying is free. A drainage survey costs a few hundred pounds and is almost never needed, because Thames checks its own records first and will look at the property itself if it is unsure.
What if Thames turns me down?: Complain to Thames first and let it run through both stages. If that gets nowhere, the Consumer Council for Water handles complaints for free. For a binding decision the route since 14 May 2026 is the Dispute Resolution Ombudsman, which took over dispute resolution for the water industry when the previous service was stopped on 24 April 2026.

This is one of about a dozen things households overpay quietly

Rainwater drainage is the sort of charge nobody reads because it sits inside a bill that arrives whether you read it or not. Untap walks through the others in the same afternoon: council tax banding, unclaimed tax relief, deposits that were never protected. Free, and we never take a share of what you get back.

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Other water companies

See every company in one table, and how the rebate works

Charges are for the 2026-27 charging year, 1 April 2026 to 31 March 2027, and come from Thames Water’s own household charges scheme. Backdating and evidence wording comes from the same document. Companies republish these every April, so the scheme is always the final word. Untap helps people in the UK find money they are already owed. We do not apply on your behalf and we do not take a share of anything you get back.