Surface water drainage rebates: are you paying for a connection you do not use?

Separate the three parts of sewerage

Ofwat’s household guide distinguishes foul sewage, surface-water drainage from your property, and highway drainage from public roads and pavements. They are different services. A home may still use the foul sewer for toilets and washing while its rainwater drains elsewhere.

Removing a property surface-water charge does not remove the highway-drainage charge. Being metered does not by itself determine eligibility: the question is where the rainwater drains and how your supplier bills the service.

Sources: Ofwat: household sewerage and drainage charges

What the supplier needs to establish

Trace the evidence, not just the nearest visible gutter. Roofs, driveways, paths and shared areas can have different drainage arrangements. Severn Trent’s household guidance asks about all rainwater, including direct or indirect drainage into public sewers; it specifically says water butts do not qualify.

Thames asks for supporting evidence such as drainage plans or relevant building-work documents. Ask which documents the company accepts before paying for a survey. Do not enter chambers or modify drainage to test a billing assumption; request the company’s investigation route if the layout is unclear.

• Check the sewerage provider named on the bill.
• Check whether the rebate is already applied.
• Gather existing drainage plans, development information and relevant photos.
• Ask about shared areas and indirect connections.
• Keep a copy of the application and written decision.

Sources: Severn Trent: household drainage rebate conditions; Thames Water: evidence and application

How much could the annual saving be?

Use the actual surface-water component confirmed by the supplier. In an illustrative £780 combined bill made up of £300 water, £390 other sewerage and £90 property surface-water drainage, removing the last component reduces the total to £690. The annual saving is £90, or £7.50 a month over twelve equal payments.

That is an 11.5% reduction in the combined bill after rounding, not a 100% reduction in sewerage. A direct debit may also include debt or credit adjustments, so compare the amended annual charge as well as the monthly collection.

Backdating is not a single national promise

Thames’ 2026/27 charges scheme defines its maximum as the current financial year plus five earlier financial years, with evidence that no surface water drained to its sewers during the relevant period. That is more specific than assuming six complete years at today’s charge.

Severn Trent says applications are considered individually; the checked web page does not fully display the dates following its “later of” wording. Ask it to confirm the start date in writing rather than importing Thames’ rule.

Illustration only: if three fully eligible earlier years had actual charges of £60, £65 and £70, the possible adjustment for those years would total £195. Multiplying the current £90 charge by three would overstate that illustration by £75. Do not include years when someone else paid the bill without checking entitlement.

Sources: Thames Water: 2026/27 charges scheme, section 9.5; Severn Trent: household drainage rebate conditions

Apply directly and question an unexplained rejection

Ofwat says using a billing agent cannot secure a larger surface-water reduction than asking your company directly. Read any proposed fee against the actual saving. If the supplier rejects a claim, ask which connection or evidence explains the decision and use its complaints process if needed.

CCW lists disputes about surface-water and highway-drainage reductions among the billing issues it can consider. Keep the bill, application, plans, decision and complaint reference. This rebate is separate from means-tested water support and from a leakage allowance.

Sources: Ofwat: applying directly versus billing agents; CCW: billing complaints it can consider