--- title: "Commercial Water Bill Rebate Calculator [2026] | Form H/01 | SoakawayCalculator.co.uk" source_url: "https://soakawaycalculator.co.uk/water-bill-rebate" retrieved_by: "AnswerRail Edge Engine v1.2.7-v27 (https://answerrail.com)" level_of_detail: "standard" token_payload_reduction: "84%" raw_html_bytes: 100387 compiled_body_bytes: 16032 entities_extracted: 6 currency_recall_static_html: "95%" monitored_currency_tokens: 40 faq_answer_recall_static_html: "57%" monitored_faq_answers: 7 link_recall_static_html: "100%" monitored_content_links: 16 rfc_compliance: "RFC 9110" last_verified_at: "2026-11-07T17:47:48.996Z" cache_age_seconds: 0 origin_cache_control: "public, max-age=0, must-revalidate" --- > **Canonical Source:** [https://soakawaycalculator.co.uk/water-bill-rebate](https://soakawaycalculator.co.uk/water-bill-rebate) > > *Free commercial water bill audit calculator for UK businesses, garden centres, dealerships, and industrial yards. Check eligibility for Surface Water Drainage (SWD) exemption and Form H/01 backdated rebates.* ### Organization: SoakawayCalculator.co.uk (UK Drainage & Stormwater Advisory Desk) | Field | Value | | :--- | :--- | | **Organization** | SoakawayCalculator.co.uk (UK Drainage & Stormwater Advisory Desk) | | **Official Website** | https://soakawaycalculator.co.uk | | **Overview** | UK civil engineering & statutory building control advisory desk for stormwater soakaway attenuation and drainage fields. | ### Entity: Soakaway Calculator UK | Property | Detail | | :--- | :--- | | **Type** | WebSite | | **Name** | Soakaway Calculator UK | ### Entity: Soakaway Calculator UK | Property | Detail | | :--- | :--- | | **Type** | WebApplication | | **Name** | Soakaway Calculator UK | ### Entity: UK BRE Digest 365 & Approved Document H3 Soil Infiltration & Rainfall Rates | Property | Detail | | :--- | :--- | | **Type** | Dataset | | **Name** | UK BRE Digest 365 & Approved Document H3 Soil Infiltration & Rainfall Rates | | **Description** | Standardised geotechnical percolation parameters (f, Vp) and 10-year / 30-year design storm depths across UK local planning authorities and soil classifications.... | ### Frequently Asked Questions (FAQ) **Q: How far must a soakaway be from a house foundation?** > A: Under Building Regulations Approved Document Part H3 (paragraph 3.25) and BS EN 752-4, a soakaway must be installed at least 5.0 metres away from any building foundation or habitable structure, and at least 2.5 metres from property boundary lines, to prevent ground destabilisation and structural subsidence. **Q: What is the standard BRE Digest 365 percolation test procedure?** > A: BRE Digest 365 requires excavating a trial pit of representative depth (typically 1.5m to 2.5m) and measuring water fall from 75% full to 25% full depth (t_75-25). The test must be filled and observed three consecutive times to simulate pre-saturated soil conditions. The soil infiltration rate f is calculated as the storage volume V_75-25 divided by effective internal surface area a_p50 multiplied by t_75-25. **Q: What happens if soil percolation test fails due to heavy clay?** > A: If the soil infiltration rate f is less than 1 x 10^-6 m/s (or Vp > 100 s/mm in BS 6297), a conventional soakaway is infeasible and will trigger Building Control failure. Under the statutory Part H3 surface water hierarchy, you are legally entitled to bypass infiltration and apply for a Section 106 connection to a surface water or combined public sewer, or discharge to an attenuation tank with a hydro-brake flow restrictor. ### Step-by-Step Procedure: How to Conduct a BRE Digest 365 Percolation Test for Building Control #### 1. Excavate Trial Pit Excavate a trial pit to the proposed soakaway invert depth (typically 0.3m wide by 1.0m to 2.0m long). Ensure the base is level and not smeared. #### 2. Fill with Water to Inflow Level Fill the trial pit rapidly with clean water to the proposed effective storage level (at least 300mm depth). #### 3. Measure 75% to 25% Drain Time Record the exact time in seconds taken for water to fall from 75% depth to 25% depth (t_75-25). #### 4. Repeat for 3 Consecutive Runs Refill the pit immediately and record times for Run 2 and Run 3 to verify soil infiltration under saturated conditions. Load typical sector figures: Garden centreVehicle yardWarehouseBuilders merchantHoliday parkCare home / school Water wholesalerUnited UtilitiesSevern Trent WaterYorkshire WaterNorthumbrian WaterSouth West WaterThames WaterAnglian WaterSouthern WaterWessex WaterWelsh Water (Dŵr Cymru)Scottish Water (Non-Household)Site area band model Water retailer (biller)Water PlusCastle WaterWave UtilitiesBusiness StreamEverflow WaterPennon Water Services / Source for BusinessClear Business WaterOther Licensed NHH RetailerCompany issuing your bills Surface rainwater drainage arrangement 100% Off-Mains: Soakaways, Attenuation Basin or Infiltration Boreholes100% surface water discharges into private soakaways or SuDS on site. 100% Off-Mains: Riparian Ditch, Stream, River or Canal OutfallDirect storm pipe to stream, canal, or uncharged private ditch. Split Site: Roof Connected, Large Permeable Gravel/Grass Yard or Partial SoakawayGravel yard, unpaved ground, or soakaways with some roof to sewer. 100% Connected to Public Surface / Combined Street SewerAll roof downpipes and yard runoff discharge into public sewer. Total site boundary area (m²)Full Land Registry perimeter area Permeable / off-mains area (m²)Gravel, soakaway, or unpaved surface Current annual SWD charge (£)Auto-estimate from tariff band Estimated: **£4,950/yr** (Band 5 (1,500 - 6,999 m²)) Years in occupation (5 years)1 year continuous occupation2 years continuous occupation3 years continuous occupation4 years continuous occupation5 years continuous occupation6 years continuous occupationLimitation Act statutory ceiling (up to 6 yrs) Optional: Pre-fill company name, postcode or SPID No water bill to hand? Leave Sewerage SPID blank — you can add it anytime in your unlocked Form H/01 workspace. Company / Trading name Site postcode Sewerage SPID (optional) Notification email ✓ OFWAT WRC FORM H/01 ELIGIBLESEC 142 WIA 1991 Estimated statutory reduction £3,530 / year + £17,650 backdated Band 5 (1,500 - 6,999 m²) → Band 4 (750 - 1,499 m²) Wholesaler charging basis United Utilities (Site-area bands) 5-year cumulative benefit £35,300 Statutory filing form Ofwat WRC Form H/01 30% utility broker fee saved £10,590 retained Preview full 3-schedule Form H/01 specimen → Download Form H/01 Rebate Pack (£245) One-off £245 fee · 0% commission · Instant VAT receipt · 30-day eligibility refund guarantee if your bill carries no reducible SWD charge. Direct retailer applications are £0. Ofwat Form H/01 Statutory BasisWRC Schedule 2 - Primary statutory authorityWIA 1991 s.142 - Non-sewered ground ratio80% Off-Mains (3,600 m²) - Retrospective claim ceiling5 Years (Limitation Act 1980) - Included dossier schedulesNotice · m² Plan · Dye Protocol DWG WRC-H01Live Cadastral Site-Area Apportionment Schematic Ofwat Form H/01 Schedule 2 ### Rebate filing route comparison | Filing route | Upfront cost | Backdating scope | Technical schedules | Net proceeds | | --- | --- | --- | --- | --- | | 1\. Bare retailer webform | £0 upfront | Capped at 1 April current year | None (ratepayer evidence) | 100% of current year only | | 2\. Contingency water broker | £0 upfront | Up to 6 statutory years | Provided by broker | 70%–75% (25%–30% fee deducted) | | 3\. Self-serve Form H/01 Dossier | £245 one-off | Up to 6 statutory years | Complete Schedules 1, 2 & 3 | 100% (keep £1,500–£5,000+ broker fee) | ## UK wholesaler drainage charging models & statutory limits Non-household surface water drainage charging policies across all 11 UK regional undertakers for the 2026/27 tariff year. | Wholesaler | Charging model | Partial yard reduction? | Standard webform limit | Evidenced Form H/01 window | | --- | --- | --- | --- | --- | | United Utilities | Site-area banding (Bands 1–8) | Yes (Carves out yard m²) | Up to 6 years | United Utilities wholesale scheme supports up to 6 years retrospective adjustment where physical non-connection (BRE 365 soakaway, French drains, unpaved gravel) is evidenced. | | Severn Trent Water | Site-area banding (Bands 1–8) | Yes (Carves out yard m²) | 1 April current year | Retailer portal applications default to 1 April of the current charging year; formal historical Form H/01 apportionment and physical evidence unlock multi-year retrospective review up to 6 years. | | Yorkshire Water | Site-area banding (Bands 1–8) | Yes (Carves out yard m²) | 1 April current year | Bare retailer applications default to 1 April of current charging year; verified Form H/01 site area surveys with historic non-connection proof support claims back to lease start (max 6 years). | | Northumbrian Water | Site-area banding (Bands 1–8) | Yes (Carves out yard m²) | 1 April current year | Direct band reductions for permeable surfaces; bare portal requests default to 1 April current charging year unless formal historic aerial/BRE 365 evidence is submitted. | | South West Water | Site-area banding (Bands 1–8) | Yes (Carves out yard m²) | 1 April current year | Allows partial area reductions where permeable/soakaway areas are surveyed and proven off-mains. Defaults to 1 April of current year; up to 6 years with formal Form H/01 technical pack. | | Thames Water | Rateable value (RV) / Metered | No (Requires 100% soakaway) | 1 April current year | Billed on Rateable Value (RV) or meter tier. 100% surface water disconnection to soakaway required for full SWD cancellation. Bare forms default to 1 April; up to 6 years with dye test evidence. | | Anglian Water | Rateable value (RV) / Metered | No (Requires 100% soakaway) | 1 April current year | RV-based or meter-based SWD tariff. Complete disconnection of roof & hardstanding to soakaways/ditches required for 100% abatement. Defaults to 1 April; 6 years with technical proof. | | Southern Water | Rateable value (RV) / Metered | No (Requires 100% soakaway) | 1 April current year | RV/meter tariff structure. Full exemption granted once verified that no surface water enters Southern Water sewerage system. Defaults to 1 April; up to 6 years with historic evidence. | | Wessex Water | Rateable value (RV) / Metered | No (Requires 100% soakaway) | 1 April current year | Standard tariff allows complete SWD exemption if roof and yard surface drainage is managed 100% via infiltration or watercourses. Defaults to 1 April; retrospective credit up to 6 years. | | Welsh Water (Dŵr Cymru) | Rateable value (RV) / Metered | No (Requires 100% soakaway) | 1 April current year | Welsh non-household rules require 100% surface water drainage to off-mains soakaways or watercourses for complete SWD charge removal. Defaults to 1 April; up to 6 years backdated with proof. | | Scottish Water (Non-Household) | Rateable value (RV) / Metered | No (Requires 100% soakaway) | Up to 5 years (Scotland) | Scottish NHH market tariffs charge drainage via RV. Full drainage exemption available when premises demonstrate zero public sewer connection. Up to 5 years backdating in Scotland. | ## Water bill rebate topic index Specific guidance and pre-configured calculation profiles for regional suppliers and commercial site categories. ### Regional wholesalers (A–S) - [United Utilities](/water-bill-rebate/united-utilities) United Utilities charges commercial premises using seven site-area bands starting at £112/yr up to £38,500/yr. Businesses with soakaways, gravel yards, or ditch outfalls can reduce charging bands and claim up to 6 years in backdated credits under Form H/01 rules. - [Severn Trent Water](/water-bill-rebate/severn-trent) Severn Trent charges non-household drainage across 8 site-area bands from £98/yr to £21,500/yr. Excluding permeable yards, soakaways, or retention areas cuts charges by £490 to £8,900/yr. Formal Form H/01 submissions unlock multi-year retrospective reviews. - [Yorkshire Water](/water-bill-rebate/yorkshire-water) Yorkshire Water bills business drainage across 6 site-area bands ranging from £145/yr to £14,500/yr. Businesses with private soakaways or extensive unpaved hardstanding can re-band their site under Form H/01 and claim multi-year retrospective adjustments. - [Northumbrian Water](/water-bill-rebate/northumbrian-water) Northumbrian Water calculates commercial drainage across 7 site-area bands from £85/yr to £11,500/yr. Proving that external yards, parking bays, or warehouses drain to soakaways eliminates or significantly cuts the tariff under Form H/01 market rules. - [South West Water](/water-bill-rebate/south-west-water) South West Water applies 5 commercial site-area bands from £110/yr to £9,800/yr. Businesses in Devon, Cornwall, and Dorset with soakaways or unpaved display ground can re-band under Form H/01, saving £1,450 to £5,850 per year. ### Regional wholesalers (S–Y) - [Thames Water](/water-bill-rebate/thames-water) Thames Water bills non-household drainage primarily via Rateable Value (RV) or fixed meter size tiers. Disconnecting 100% of surface runoff into soakaways or attenuation eliminates charges entirely, saving London and Thames Valley premises £400 to £6,500/yr. - [Water Plus](/water-bill-rebate/water-plus) Water Plus is the UK’s largest non-household water retailer, billing customers across United Utilities and Severn Trent regions. Businesses with private soakaways or permeable yards can instruct Water Plus to lodge Form H/01, securing £500 to £12,000+ in annual and backdated credits. - [Castle Water](/water-bill-rebate/castle-water) Castle Water bills thousands of commercial ratepayers across Thames Water and Scottish Water networks. If your premises drain rainwater into private soakaways or watercourses, Castle Water must update CMOS to eliminate the SWD charge, unlocking substantial backdated credits. - [Wave Utilities](/water-bill-rebate/wave-utilities) Wave Utilities serves non-household customers primarily across Anglian and Northumbrian Water territories. Businesses with soakaways or extensive aggregate yards can reduce or cancel drainage charges via Wave under Ofwat Form H/01 procedures. - [Business Stream](/water-bill-rebate/business-stream) Business Stream provides water retail across Scotland, Yorkshire, and Southern Water areas. Commercial premises discharging rainwater into soakaways or natural watercourses can claim up to 5 years (Scotland) or 6 years (England) in backdated drainage refunds. ### Commercial property sectors - [Garden Centres & Nurseries](/water-bill-rebate/garden-centres-and-nurseries) Garden centres are among the most overcharged commercial water customers. Expansive gravel yards, poly-tunnels, and outdoor plant display beds drain naturally into subsoil rather than sewers. Site-area re-banding routinely drops bills by £2,000 to £8,000/yr plus 5-figure backdated refunds. - [Car Dealerships & Vehicle Yards](/water-bill-rebate/car-dealerships-and-vehicle-yards) Car showrooms with large external vehicle display forecourts or unpaved storage yards are frequently assigned to punitive drainage bands. By proving that external yard runoff infiltrates via permeable ground or private soakaways, dealerships save £1,800 to £4,500 annually. - [Builders Merchants & Aggregates](/water-bill-rebate/builders-merchants-and-aggregates) Builders merchants and aggregate stockyards feature extensive unpaved hardcore and gravel ground that absorbs rainfall. Water retailers mistakenly bill the entire perimeter, costing businesses £3,000 to £14,000/yr in unwarranted drainage levies. - [Industrial Estates & Warehouses](/water-bill-rebate/industrial-estates-and-warehouses) Modern and rural industrial estates often feature private attenuation basins, crate soakaways, or ditch outfalls built during development. If your warehouse roof drains to soakaways, you are entitled to a 100% drainage rebate saving £1,200 to £6,000/yr. - [Caravan & Holiday Parks](/water-bill-rebate/caravan-and-holiday-parks) Covering multiple hectares of grass, parkland, and gravel roadways, holiday parks are frequently placed in the highest drainage tariff bands (£15,000–£38,000+/yr). Carving out non-draining grass acreage drops tariffs drastically and secures major retrospective rebates. - [Care Homes & Schools](/water-bill-rebate/care-homes-and-independent-schools) Campus facilities with large landscaped gardens, sports grounds, and dedicated soakaway infrastructure regularly pay thousands in erroneous drainage tariffs. 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