Where Otter works

See where local forecasts are available.

We map the areas served by England’s main water companies and all 23 Dŵr Cymru areas. The postcode checker can identify your usual supplier and local supply area. Forecast availability is shown separately because not every mapped area has enough data yet.

17main English water companies

129mapped local supply areas

36/101areas with a local forecast35 available now; 1 waiting for a fresh reading

9smaller suppliers missing exact site boundaries

How many people are covered

A local water forecast is available in areas covering 78% of England’s population.

Forecasts are available in 36 of 101 local supply areas across 16 of 17 water companies. Some cover the whole local system; others track one important reservoir, river or groundwater source and are labelled as partial.

The covered areas include large populations in London, Yorkshire and the North West. The percentage uses Census 2021 population data, so it is a guide rather than a live count. The postcode checker decides whether a particular address is covered.

Right now 35 areas are available, covering 77.1% of Census 2021 residents. Another 1 are paused because a required official reading is late or missing. They return automatically when the data does.

Experimental hosepipe-risk warnings are currently available for 8 water-company areas. Together they cover 58.7% of England’s population. These deliberately cautious warnings show current pressure rather than predicting a ban date or probability. Areas without a current warning remain clearly marked. Official water-company notices always take priority.

What the map covers

Main water-company areas are mapped. Some smaller sites are not.

Your postcode is checked against the official supply-area map to find the main water company and local supply area for your address.

Some new developments have a smaller independent water company. Ofwat keeps those site boundaries separately and they change over time. Until we can add every boundary, an address inside one of those developments may show the surrounding main supplier.

Environment Agency supply-area data ↗Ofwat smaller-supplier register ↗

How we choose the area for a warning

Use the company area unless official evidence shows a smaller one.

A postcode identifies the water company and local supply area. We then use the same area the company uses for restrictions. An official notice always overrides any forecast.

01Whole company

When one restriction covers all of the company’s customers.

02Group of areas

When one restriction covers several named supply areas.

03Local supply area

The normal choice when restrictions vary within a company.

04Smaller operating area

Only when an official notice clearly defines it.

Supplier	Usual warning area	Water-level area	Short-term warning area
Affinity WaterAffinity's 2012 and 2026 Central restrictions applied across Central zones 1–6; the key-well experiment must not be transferred to its Southeast or East zones.	Affinity Central zone group where applicable	Experimental warning	Background information
Anglian WaterThe statutory drought-planning default is a local supply area or larger; a smaller area needs specific evidence.	Water Resource Zone	Experimental warning	Background information
Bristol WaterThe published supplier geography contains one local supply area, so supplier and statutory planning scope are equivalent.	Whole supplier area	Waiting for usable data	Background information
Cambridge WaterThe published supplier geography contains one local supply area, so supplier and statutory planning scope are equivalent.	Whole supplier area	Research only	Background information
Essex & Suffolk WaterThe statutory drought-planning default is a local supply area or larger; a smaller area needs specific evidence.	Water Resource Zone	Research only	Background information
Northumbrian WaterThe statutory drought-planning default is a local supply area or larger; a smaller area needs specific evidence.	Water Resource Zone	Waiting for usable data	Background information
Portsmouth WaterThe published supplier geography contains one local supply area, so supplier and statutory planning scope are equivalent.	Whole supplier area	Waiting for usable data	Background information
SES WaterThe published supplier geography contains one local supply area, so supplier and statutory planning scope are equivalent.	Whole supplier area	Research only	Background information
South East WaterRestrictions have changed scope between Kent and a wider western/Sussex area, so those stages are separate decision areas.	Kent or western-and-Sussex zone group	Experimental warning	Experimental warning
South Staffs WaterThe published supplier geography contains one local supply area, so supplier and statutory planning scope are equivalent.	Whole supplier area	Research only	Background information
Severn Trent WaterThe statutory drought-planning default is a local supply area or larger; a smaller area needs specific evidence.	Water Resource Zone	Waiting for usable data	Background information
Southern WaterSouthern Water's Hampshire and Isle of Wight restrictions cover seven named resource zones under one Western-area decision process; Kent and Sussex do not inherit that warning.	Hampshire and Isle of Wight group where applicable	Available	Background information
South West WaterThe 2022 Colliford and 2023 Roadford restrictions followed resource-zone supply areas, while the July 2026 restriction was a smaller documented operational exception.	Water Resource Zone, with documented exceptions	Experimental warning	Experimental warning
Thames WaterThe published reservoir baseline represents the London local supply area; other Thames zones must not inherit that numerical outlook.	Water Resource Zone; London model where applicable	Experimental warning	Background information
United UtilitiesThe statutory drought-planning default is a local supply area or larger; a smaller area needs specific evidence.	Water Resource Zone	Experimental warning	Background information
Wessex WaterThe published supplier geography contains one local supply area, so supplier and statutory planning scope are equivalent.	Whole supplier area	Waiting for usable data	Background information
Yorkshire WaterRecent Yorkshire restrictions were supplier-wide and its integrated Grid zone serves more than 99% of customers.	Whole Yorkshire Water region	Available	Background information
Dŵr Cymru Welsh WaterThe statutory drought-planning default is a local supply area or larger; a smaller area needs specific evidence.	Water Resource Zone	Not ready	Not ready
Hafren DyfrdwyThe statutory drought-planning default is a local supply area or larger; a smaller area needs specific evidence.	Water Resource Zone	Not ready	Not ready
Veolia Water ProjectsThe statutory drought-planning default is a local supply area or larger; a smaller area needs specific evidence.	Water Resource Zone	Not ready	Not ready

Our test history contains 31 clearly defined restriction events across 12 water companies. When a restriction expanded in stages, each stage is kept separate. See the test data

Water company	Past restrictions spotted	False alarms avoided	Status
Yorkshire WaterWhole supplier region. The frozen regional threshold passed the recall-first later test checks and is served as watch/no-current-signal, never as a probability.	2/2 separate starts detected	14/16 historical quiet years stayed quiet	Warning available
Thames WaterLondon public preview; five non-London zones remain research only. The early preview caught every known London restriction start, including the held-back later test. Eleven quiet seasons would also have shown an early watch, which is accepted here because this is a deliberately cautious risk signal with a clear disclaimer, never a ban probability. A separate research-only Thames Valley build transfers the London-led company-wide policy arm and preserves Farmoor, Kennet, Wey and Stonor as distinct local systems. Exact-gauge measured Farmoor flow now supports the 2025 SWOX event, and exact Tilford flow reproduces the Guildford plan's 1976 example, but neither supplies an tested on later data local warning. Only London increases public warning reach.	1/1 temporal later test start detected; 4/4 total replay	14/25 quiet seasons stayed quiet; early warnings are intentional	Experimental warning
South East WaterEight zones; groundwater and operational pressures kept separate. Public experimental warning: dry weather creates a light alert, while a stronger warning requires supplier-weighted groundwater or reservoir confirmation. The slow-resource rule detected the held-back 2025 start 32 days ahead, and official operational alerts cover fast pressure episodes. This is an early risk warning, not a ban forecast or probability.	2025 slow-resource later test detected 32 days ahead; 4/4 combined replay	0/33 warning weeks in the separate 2024 quiet later test	Experimental warning
South West WaterStrategic reservoir systems and separate operational episodes. Public experimental warning for the four mainland supply areas: dry weather creates a light alert, strategic-reservoir stress creates a stronger warning in the storage-led zones, and official supplier alerts cover operational events. The Isles of Scilly remain unavailable because the mainland evidence is not transferred there. This is a risk warning, not a ban forecast.	2/2 slow-resource episodes detected; 2026 operations detected only at announcement	59/65 later 2024–2025 quiet weeks stayed quiet	Experimental warning
Affinity WaterCentral zones 1–6. Public low-confidence warning for Central zones 1–6: dry weather creates a light alert and sustained groundwater stress creates a stronger warning. It caught 2012 but missed the demand-led 2026 event, so the page explicitly marks short-term demand, transfers, treatment and operating pressure as not fully observed. This is a cautious risk alert, not a forecast.	1/2 starts detected; the 2026 demand-led event was missed	0/32 warning weeks in the later 2025 quiet period	Experimental warning
Cambridge WaterCambridge Water Resource Zone. The threshold frozen from the 1991 restriction missed the held-back 2026 demand-led event. A retrospective liberal threshold catches it but was chosen after the later test and falsely signals in 13 of 33 quiet seasons.	0/1 held-back start detected	31/33 pre-later test quiet seasons stayed quiet	Research only
Southern WaterHampshire and Isle of Wight. The frozen 28-day River Test recession rule caught the held-back 2025 and 2026 starts. Its one retained false alarm coincided with a real 2019 drought-permit application; it is served only as a watch, never a probability.	2/2 temporal later test starts detected	4/5 post-2019 no-ban seasons stayed quiet	Warning available
SES WaterWhole supplier Water Resource Zone. A frozen Chipstead-plus-six-month-rainfall rule replays the 2005 fitting episode and 2012 start. The new Bough Beech archive explains the only later false signal, but begins in 2016 and therefore cannot test event-era recall or make the retrospective architecture separate.	1/1 retrospective start detected; 0 held-back starts available	13/14 later no-ban seasons stayed quiet	Research only
Essex & Suffolk WaterEssex reservoir arm, Suffolk Rook Hall groundwater arm and Northern Central river-source map. The Essex reservoir arm signals six days before the 2026 start. The supplier-named Rook Hall arm replays the 1997 Suffolk start 365 days early and supplies live groundwater context for Hartismere and Blyth. Exact qualified Ingworth flow and two upstream Waveney proxy histories are complete, but the exact Ellingham Mill licence-flow series is not publicly exposed. No public coverage is added until the four-zone source replay is complete and separately tested.	2/2 known starts replayed retrospectively; 0 held-back starts; only Essex source-matched at the 2026 signal	The deliberately sensitive Rook Hall arm false-signals in 2019, 2022 and 2025	Research only
Anglian WaterEast region excluding Hartlepool; layered groundwater warning. Public experimental warning for Anglian's East region excluding Hartlepool: dry weather creates a light alert and persistent stress across supplier-linked groundwater sites creates a stronger warning. The development replay detected both known starts and stayed quiet throughout the later 2025 period. Missing demand and operating inputs are disclosed, and the level is never presented as a ban probability.	2/2 starts detected in development replay; 2026 first signal 179 days ahead	0/32 warning weeks in the later 2025 quiet period	Experimental warning
Bristol WaterSingle Bristol Water Resource Zone. The former historical reservoir replay has been removed. The 1975-76 event predates available data, the 1990 canal-failure restriction lacks a usable pre-event reading, and current supplier facts alone cannot validate a warning.	Historical reservoir replay removed	No reusable long reservoir history	Waiting for usable data
Northumbrian WaterKielder and Berwick-Fowberry systems separately. Northumbrian says it has never needed Level-2, Level-3 or Level-4 restrictions. Its Kielder supply area decision uses Whittle Dene, Northumbrian Derwent and Weardale trigger systems, while Berwick-Fowberry uses a separate groundwater trigger. The long public Kielder and Teesdale series do not reproduce that architecture, so there is neither an event-recall test nor a decision-complete quiet replay. Still needed: A approved covering the same dates history for the three Kielder trigger systems and Berwick groundwater, plus a future separately observable restriction start; no threshold can manufacture the missing positive outcome. Sources: Northumbrian Water Drought Plan 2022 ↗; Northumbrian Water Drought Plan 2022 appendix ↗	0 target-safe restriction starts available	Public Kielder/Teesdale histories do not represent all statutory trigger systems	Waiting for usable data
Portsmouth WaterSingle Portsmouth Water Resource Zone. Portsmouth last imposed restrictions in 1976. Its decision-leading Well X record spans more than 80 years, but the site's identity and absolute history are not shown; the public current page gives only an anomaly from average. That cannot reconstruct target-safe trigger crossings or test event recall. Still needed: A approved absolute Well X history with dated trigger curves and the 1976 pre-decision window, or a supplier-approved public surrochecks demonstrated against Well X. Sources: Portsmouth Water current resource position ↗; Portsmouth Water 2026 drought-trigger review ↗	0 target-safe restriction starts in the public-data era	Current public reporting exposes an anomaly, not the absolute trigger history	Waiting for usable data
South Staffs WaterSingle South Staffs Water Resource Zone. The 1976 restriction predates the public Blithfield archive. In 2025 the statutory Level-2 curve was crossed but South Staffs decided not to impose a TUB. The monthly public series also omits River Severn support, groundwater, demand and operations, so the curve remains research context and the corrected level backtest still publishes no forecasts.	0 target-safe restriction starts available	0/1 separately verified modern Level-2 no-ban counterexamples stayed quiet	Research only
Severn Trent Water1995 whole-supplier event; current Derwent Valley indicator represents only Strategic Grid East. The historical Derwent and Clywedog component replay has been removed. The separately reusable regional-total history begins in 2023, so it cannot reconstruct the 1995 event or enough quiet seasons for a warning model.	1995 component replay removed	separate regional-total history starts in 2023	Waiting for usable data
United UtilitiesStrategic Resource Zone layered reservoir context. Public low-confidence resource watch: current North West climate and regional storage are shown together, but the page states clearly that the usable reservoir archive begins after the 2010 ban and the warning is therefore untested against an implemented local ban. It is a broad early-risk alert, never a ban forecast or probability.	2010 start cannot be scored because resource history begins in 2016	216/227 diagnostic quiet weeks stayed quiet; warnings occurred in 2020 and 2025	Experimental warning
Wessex WaterSingle integrated Wessex Water Resource Zone. Wessex last imposed a hosepipe ban in 1976. In 2022 its reservoirs entered Level 2, but the overall integrated position stayed at Level 1b because groundwater remained stronger, and no ban was imposed. The retained Woodyates groundwater indicator cannot represent the mixed-system decision, while the wider historical resource state is not publicly covering the same dates. Still needed: A covering the same dates history of the integrated reservoir, groundwater, river, transfer and demand state extending to a restriction start. The planned wider reservoir feed alone will improve context but cannot supply the missing 1976 system state. Sources: Wessex Water Drought Plan ↗; Wessex Water WRMP24 drought review ↗	0 target-safe restriction starts in the public-data era	2022 is a verified reservoir-Level-2/no-ban counterexample	Waiting for usable data

8 of 12 tested company warnings are ready to show publicly. We checked all 17 English water companies; 5 do not have enough public history for a fair warning test. Available warnings cover 58.7% of Census 2021 residents. Research tests do not count toward that figure. Otter reports four warning levels and never gives a percentage chance of a hosepipe ban.

Forecasts by water company

Water-level forecasts and hosepipe warnings are checked separately.

All 17 companies are on the map. 16 have some forecast data. A water-level forecast can be available even while its separate hosepipe-warning test is still in an early preview.

AFW8 supply areas

Affinity Water

South East and eastern England

Main water sources: Groundwater-led
Local forecast: Partly available
Hosepipe warning: Experimental warning

Central zones 1–6 receive tested Lilley Bottom forecasts and a public low-confidence hosepipe-risk warning. The warning shows dry-weather pressure separately from groundwater confirmation and states that short-term operational pressure is not fully observed. Southeast/Dour receives a current Wolverton seasonal position and tested 90-day forecast; East/Brett remains blocked because the Lady Lane series ends in 2020.

See how it was tested

AWS27 supply areas

Anglian Water

East of England

Main water sources: Mixed reservoirs, rivers and groundwater
Local forecast: Partly available
Hosepipe warning: Experimental warning

Ruthamford North and South receive a tested 30-day East England reservoir forecast. Anglian's East region excluding Hartlepool also receives a public experimental warning that separates dry-weather pressure from sustained stress across supplier-linked groundwater sites. Missing demand and operating inputs are shown as limitations rather than hidden.

Postcode checker live · details above

BWX1 supply area

Bristol Water

Bristol and surrounding area

Main water sources: Reservoir-led mixed system
Local forecast: Partly available
Hosepipe warning: Waiting for usable data

The single Bristol supply area receives a passing 30-day Blagdon forecast rebuilt from Environment Agency reports and anchored to Bristol Water's current named-reservoir reading. It is one of four major reservoirs, not the complete reservoir group, canal, groundwater or operating position.

Postcode checker live · details above

CAM1 supply area

Cambridge Water

Cambridge and South Cambridgeshire

Main water sources: Groundwater-led
Local forecast: Available
Hosepipe warning: Research only

The one Cambridge supply area receives a seasonal index from all five official drought-trigger boreholes; its 30- and 90-day forecasts pass. A research-only fast-stress arm adds all four exact river gauges and the pre-event 110 Ml/d operational boundary, which detects the 2026 ban but lacks continuous historic demand and production data for full validation.

Postcode checker live · details above

ESW4 supply areas

Essex & Suffolk Water

Essex and Suffolk

Main water sources: Mixed reservoir and river system
Local forecast: Partly available
Hosepipe warning: Research only

The Essex supply area receives tested 30- and 60-day combined Hanningfield and Abberton forecasts from a reproducible official history. The failed 90-day forecasts is not shown. A seasonal-decile restriction transfer remains research-only after a 2025 false alarm and cannot represent the three Suffolk zones.

Postcode checker live · details above

NWL2 supply areas

Northumbrian Water

North East England

Main water sources: Reservoir and river system
Local forecast: Partly available
Hosepipe warning: Waiting for usable data

The Kielder supply area receives tested 60- and 90-day Kielder forecasts anchored to Northumbrian Water's current Northumberland (including Kielder) reading. The 30-day forecasts and the separate Berwick-Fowberry groundwater zone remain not shown.

Postcode checker live · details above

PWS1 supply area

Portsmouth Water

South Hampshire and West Sussex

Main water sources: Groundwater-led
Local forecast: Not ready
Hosepipe warning: Waiting for usable data

The one supply area is mapped, but Portsmouth's primary 80-plus-year “Well X” history and location are private/anonymised. Its public page gives only the current anomaly from average.

Supply area mapped · forecast not ready

SES1 supply area

SES Water

Surrey, Sussex and Kent

Main water sources: Mixed groundwater and reservoir system
Local forecast: Partly available
Hosepipe warning: Research only

Chipstead's four Chalk forecasts and Bough Beech's monthly reservoir forecasts pass their separate checks. Qualified Riverhead history now covers the Lower Greensand reference site, but stays research-only until SES supplies numerical trigger values and event-era Bough Beech storage supports a reproducible combined backtest.

Postcode checker live · details above

SEW8 supply areas

South East Water

Kent, Sussex, Surrey, Hampshire and Berkshire

Main water sources: Mixed reservoirs, rivers and groundwater
Local forecast: Partly available
Hosepipe warning: Experimental warning

The Haywards Heath area receives Ardingly's tested 90-day forecast. All eight South East Water supply areas receive the public experimental hosepipe-risk warning, which combines broad dry-weather pressure with locally weighted groundwater or reservoir confirmation and keeps fast supplier operational alerts separate.

Postcode checker live · details above

SSW1 supply area

South Staffs Water

West Midlands and South Staffordshire

Main water sources: Mixed groundwater and reservoir system
Local forecast: Partly available
Hosepipe warning: Research only

The Environment Agency's qualified Bewdley series supports tested 30-, 60- and 90-day five-day-mean River Severn flow forecasts from the robust Huber v0.2 model, with separate low-flow checks. It is a direct source component, not total system storage. The corrected Blithfield model remains a failed-checks early preview and the 2025 Level-2/no-ban restriction audit remains research-only.

Postcode checker live · details above

SVT15 supply areas

Severn Trent Water

Midlands and parts of Wales

Main water sources: Mixed reservoirs, rivers and groundwater
Local forecast: Partly available
Hosepipe warning: Waiting for usable data

The Strategic Grid retains its separately sourced supplier regional-total forecast and adds passing Derwent Valley component forecasts. The commissioned transfer also supports a separately scoped Derwent Valley indicator for Nottinghamshire. Clywedog fails every replacement interval checks and remains not shown.

Postcode checker live · details above

SWS14 supply areas

Southern Water

Kent, Sussex, Hampshire and Isle of Wight

Main water sources: Mixed groundwater, river and reservoir system
Local forecast: Partly available
Hosepipe warning: Warning available

Both Kent Medway zones retain Riddles Lane groundwater and add tested 60- and 90-day Bewl forecasts, with the current chart parser labelled early preview. Worthing retains a passing groundwater forecasts; Hampshire zones retain Total Test Flow and mapped groundwater where applicable. These are scoped components, not total storage or ban probabilities.

Postcode checker live · details above

SWW5 supply areas

South West Water

Cornwall, Devon, Dorset and Bournemouth

Main water sources: Reservoir-led mixed system
Local forecast: Partly available
Hosepipe warning: Experimental warning

Roadford, Colliford and Wimbleball receive scoped tested reservoir forecasts and public experimental hosepipe-risk warnings. Bournemouth receives the lighter dry-weather level with its missing demand and treatment inputs stated explicitly. The mainland warning is not transferred to the Isles of Scilly.

Postcode checker live · details above

TWS6 supply areas

Thames Water

London and the Thames Valley

Main water sources: Mixed, zone-specific system
Local forecast: Partly available
Hosepipe warning: Experimental warning

The London local supply area receives the tested 14-, 30-, 60- and 90-day reservoir-level outlook from the latest freshness-checksd weekly observation. Its separate high-recall warning is a early preview; the other five zones remain without a forecast.

See how it was tested

UUX4 supply areas

United Utilities

North West England

Main water sources: Reservoir-led mixed system
Local forecast: Partly available
Hosepipe warning: Experimental warning

The Strategic supply area receives tested 30-, 60- and 90-day forecasts from the Environment Agency's North West regional reservoir trace and a public low-confidence resource-pressure watch. The warning states that its reservoir history begins after the 2010 ban and is therefore untested against an implemented local ban. North Eden and Barepot remain without a numerical model.

Postcode checker live · details above

WXW1 supply area

Wessex Water

South West and southern England

Main water sources: Mixed groundwater, river and reservoir system
Local forecast: Partly available
Hosepipe warning: Waiting for usable data

The single Wessex supply area retains the official Woodyates groundwater trigger and its passing 30-day forecasts. A replacement Clatworthy history also passes its 30-day checks; the secondary projection is not shown whenever its monthly target has elapsed, and the wider supplier reservoir feed is still scheduled for March 2027.

Postcode checker live · details above

YWS2 supply areas

Yorkshire Water

Yorkshire

Main water sources: Integrated reservoirs, rivers and groundwater
Local forecast: Available
Hosepipe warning: Warning available

Every Yorkshire Water postcode receives the supplier-wide seasonal-change resource outlook. It uses the separately licensed reservoir feed and does not use the removed operational supply-system polygons.

See how it was tested

What is still missing

Every gap has a clear reason.

When a full company forecast is not possible, we name what we can show, what is missing and what would fix it. We never let one nearby reservoir or borehole stand in for an entire water supply.

2companies with full forecasts

14companies with partial forecasts

0early previews

1waiting for public data

AFWAffinity WaterPartly covered

Available now

Central zones 1–6: Lilley Bottom 14- and 60-day groundwater-level forecasts. Southeast/Dour: current Wolverton seasonal position and a passing 90-day forecasts.

Not covered

Affinity East/Brett, plus imported Grafham support and the rest of the Central and Southeast source portfolios.

Why

Lady Lane is the official East key well but its public EA series ends in March 2020. Central now has all five supplier-named key-well histories plus audited Grafham storage context, but the 2026 restriction was demand-led while groundwater was just above average and Grafham was 88% in the last report before announcement. Public daily demand, actual Grafham transfer, treatment and abstraction-headroom histories remain unavailable. Wolverton remains a Southeast sentinel rather than a complete system measure.

What would fix it

Restore or obtain a approved current Lady Lane series for East; obtain covering the same dates demand, delivered transfers, treatment and abstraction headroom for all three regions; preserve each verified station-to-zone relationship and repeat the frozen split for added components.

AWSAnglian WaterPartly covered

Available now

Ruthamford North and South: 30-day East England regional reservoir forecasts containing Grafham and Rutland. The research build also carries six current named-reservoir observations and completed exact source collection for eleven boreholes and five river gauges across eleven mapped supply areas.

Not covered

Pitsford and the rest of the Ruthamford operating system, plus all other 25 supply areas and their direct-river, groundwater, transfer and operating-state components.

Why

The official East England regional trace passes only at 30 days and also contains Abberton and Hanningfield, while omitting Pitsford. Grafham and Rutland individually pass no forecasts. All 20 exact OGL jobs have finished; 17 contain usable qualified histories, while three secondary groundwater measures publish no usable observations. The 11 source-mapped supply areas still omit transfer, demand, treatment-output and operating-headroom histories, and the official material does not state how to combine the paired Wensum and Wissey gauges against the published system thresholds.

What would fix it

Keep the regional and current named-reservoir histories fresh; seek a approved formula for the paired Wensum and Wissey gauges and otherwise retain them as separate context; repeat the provisional groundwater replay only after the source set is frozen; and add definition-consistent transfer, demand, treatment-output and operating-headroom histories for the remaining zones.

BWXBristol WaterPartly covered

Available now

Single Bristol supply area: Blagdon Reservoir 30-day storage forecasts.

Not covered

The complete Bristol local supply area, including reservoirs, canal imports, groundwater, treatment state, demand and operating constraints.

Why

The separate Environment Agency archive supports only Blagdon's 30-day forecasts. The 60- and 90-day checks fail, and Blagdon alone cannot reproduce Chew Valley, Cheddar, Barrow, canal imports, groundwater, demand or operating constraints.

What would fix it

Obtain a definition-consistent four-reservoir history together with canal, groundwater, treatment, demand and operating inputs, then validate a frozen complete-system model while retaining the passing Blagdon component unchanged.

ESWEssex & Suffolk WaterPartly covered

Available now

Essex supply area: combined Hanningfield and Abberton 30- and 60-day reservoir-level forecasts.

Not covered

The failed Essex 90-day forecasts; Northern Central, Hartismere and Blyth local supply areas; non-reservoir components within Essex.

Why

The capacity-weighted official reservoir-map history supports two tested Essex forecasts, but its 90-day interval covers only 41.7% of later outcomes. Rook Hall provides research-only groundwater context for Hartismere and Blyth. Exact qualified Ingworth flow and two upstream Waveney proxy histories are now complete for Northern Central, but the exact Ellingham Mill licence-flow series is not publicly exposed and the proxies cannot be relabelled as that statutory trigger.

What would fix it

Keep the exact Ingworth and explicitly labelled Waveney proxy histories fresh, obtain a approved Ellingham replacement if possible, and add Essex transfer, river and operating-state histories. Preserve the frozen Essex evaluation rules and publish only tested additions.

NWLNorthumbrian WaterPartly covered

Available now

Kielder supply area: current Northumberland (including Kielder) reading with passing 60- and 90-day Kielder forecasts.

Not covered

The complete Kielder conjunctive operating state and the Berwick-Fowberry supply area.

Why

The direct Kielder reservoir indicator passes at 60 and 90 days, but the 30-day forecasts fails the unchanged accuracy checks. Public observations do not provide a definition-consistent history for Kielder, Weardale, rivers and groundwater together, and Fowberry still lacks a separate public groundwater series.

What would fix it

Obtain source-group histories and operating-state variables for the Kielder system plus a separate Fowberry groundwater series; retain each as a scoped model unless the supplier sanctions an integrated index.

PWSPortsmouth WaterWaiting for public data

Available now

None.

Not covered

The single Portsmouth local supply area.

Why

Portsmouth identifies an 80-plus-year regional observation borehole called “Well X” as its primary drought indicator, but its identity and absolute history are not shown from the public report for security. The public current page gives only an anomaly from average. Named Environment Agency sites are described as supporting checks, not a approved replacement.

What would fix it

Secure supplier/API access to the absolute monthly Well X series or obtain a supplier-approved public multi-borehole index, mapping and current absolute observation.

SESSES WaterPartly covered

Available now

Single SES supply area: Chipstead Chalk-reference forecasts at 14, 30, 60 and 90 days, separately checksd Bough Beech reservoir forecasts, and a qualified Riverhead Lower Greensand research history from the Environment Agency.

Not covered

Exact numerical Riverhead trigger bands and a supplier-approved integrated decision rule combining Chalk, Lower Greensand and surface-water components.

Why

Riverhead removes the Lower Greensand history gap: its qualified manual record begins in 1965 and its logged daily record in 2005. SES publishes Riverhead's official trigger bands only as charts, however, and Bough Beech's reproducible storage history begins after both known restrictions. Those limits prevent an exact three-component event backtest.

What would fix it

Obtain SES's numerical Riverhead trigger table and pre-2016 Bough Beech storage, then freeze and separately test the documented three-component operational review without changing the passing Chipstead or Bough Beech component models.

SEWSouth East WaterPartly covered

Available now

Haywards Heath area: Ardingly Reservoir 90-day storage forecasts.

Not covered

The other seven supply areas and the groundwater, river, transfer and Arlington components of the mixed system.

Why

Ardingly's separate replacement history passes only the 90-day checks and is local to Haywards Heath. All 27 exact OGL histories for the draft 2027 plan's 17-borehole matrix are now usable for current complete-month context across all eight zones, but the public Stonor Park series begins in 2015 and cannot provide a long separate Bracknell backtest. The printed Hazelwood trigger table is also on an incompatible elevation scale. Continuous demand, treatment-headroom and the remaining surface-water and transfer histories are unavailable.

What would fix it

Keep the completed groundwater source arm separate from the frozen rainfall rule; obtain a licensed older Stonor series for a full Bracknell evaluation and a corrected supplier Hazelwood trigger table; commission the remaining reservoir and transfer components; and separately obtain continuous demand, treatment and treated-storage inputs before validating a restriction warning.

SSWSouth Staffs WaterPartly covered

Available now

Single South Staffs supply area: Bewdley five-day mean River Severn flow forecasts at 30, 60 and 90 days.

Not covered

Blithfield Reservoir, Sherwood Sandstone groundwater and the integrated supply-demand state of the single South Staffs local supply area.

Why

The official qualified Bewdley history now supports a separately labelled River Severn component, but it does not measure Blithfield, groundwater, demand, transfers or treatment headroom. The corrected 2016–2026 Blithfield early preview still passes no forecasts under its frozen checks.

What would fix it

Obtain a machine-readable daily or weekly Blithfield series plus representative groundwater and operating-state histories; preserve the frozen Bewdley result and validate every additional component before considering a supplier-approved integrated index.

SVTSevern Trent WaterPartly covered

Available now

Strategic Grid: separately sourced supplier regional-total 14-day and four-week forecasts plus Derwent Valley 30-, 60- and 90-day component forecasts. Nottinghamshire: the same three Derwent Valley transfer indicators.

Not covered

The remaining Strategic Grid components, the Nottinghamshire conjunctive system and 13 other supply areas.

Why

The regional total and Derwent Valley are direct-supply components rather than the complete supply-demand system. Clywedog's sparse replacement history fails every interval checks. No public archive reconciles reservoirs, regulated rivers, transfers, treatment state and groundwater to all 15 supply area definitions.

What would fix it

Keep the separate regional-total history fresh; obtain reusable dated histories for the remaining strategic sources and non-grid zones, together with supplier-approved mappings and any integrated operating index, then validate per system.

SWSSouthern WaterPartly covered

Available now

Kent Medway East and West: Riddles Lane groundwater plus Bewl Reservoir 60- and 90-day forecasts. All seven Hampshire and Isle of Wight zones: Total Test Flow 14-, 60- and 90-day numerical forecasts and the River Test restriction watch; the 30-day flow forecasts is not shown. Supplier-mapped Clanville and West Meon groundwater observations are added in five Hampshire zones with failed groundwater forecasts not shown. Sussex Worthing receives a current Chilgrove/Whitelot index and passing 60-day forecasts. Sussex Brighton and Kent Thanet receive current mapped groundwater observations with all forecasts not shown.

Not covered

Sussex North and Sussex Hastings; Carisbrooke groundwater for the Isle of Wight; groundwater specific to Southampton West; and the remaining river, transfer, storage, demand and operating components of every partially represented system.

Why

The mapped EA boreholes and Bewl materially improve visibility but remain components, not total system storage. The current Bewl chart parser is still a labelled early preview. Clanville, West Meon, Brighton and Thanet fail every frozen forecast checks and are observation-only; Carisbrooke and comparable histories for other rivers, transfers, storage, demand and operating state remain incomplete.

What would fix it

Keep the EA groundwater and four-gauge Total Test Flow batches fresh; obtain Carisbrooke and the missing zone-specific groundwater, river, transfer and strategic-storage histories; publish only supplier-approved combined indices or separately scoped indicators, and continue withholding failed forecasts.

SWWSouth West WaterPartly covered

Available now

Roadford supply area: Roadford Reservoir 90-day forecasts. Colliford supply area: Stithians 30-, 60- and 90-day forecasts. Wimbleball supply area: South-west England regional reservoir 30-day forecasts.

Not covered

Direct Colliford and Wimbleball forecasts, plus Bournemouth and the Isles of Scilly and every zone's without a forecast river, groundwater, transfer, demand and operating components.

Why

The replacement archive supports Roadford at 90 days, Stithians at all three monthly forecasts and the regional trace containing Wimbleball at 30 days. The governing-plan source build maps all 18 weekly river-flow sites to exact qualified Environment Agency measures and two of four reported groundwater sites to public stations; those histories remain research-only while their batch downloads finish. Direct Colliford and Wimbleball models still fail their publication checks, current Colliford and Roadford control-curve revisions are not machine-readable, and continuous demand, treatment headroom, treated storage, network pressure, transfers and Isles of Scilly operating history remain incomplete.

What would fix it

Keep the three scoped indicators current; finish the exact river and groundwater batches; test every added source separately without altering failed results; obtain reusable interim control curves and continuous demand, treatment, treated-storage, pressure and transfer histories; and build Bournemouth and the Isles of Scilly as distinct operating systems.

TWSThames WaterPartly covered

Available now

London local supply area: 14-, 30-, 60- and 90-day reservoir-level forecasts.

Not covered

Thames Water's other five local supply areas.

Why

London uses the latest freshness-checksd Environment Agency weekly Lower Thames and Lower Lee observation. Farmoor now has source-audited monthly storage plus an exact-gauge qualified daily measured-flow history; the flow supports the 2025 SWOX event, but it is not the plan's naturalised DEL-scenario trigger flow and every Farmoor storage forecasts still fails. Tilford's exact qualified history reproduces the Guildford protocol's 1976 fitting example but has no separate restriction outcome. Theale exposes no public flow measure. Stonor's public 2015-onward logger provides too few qualifying low-level origins for SWA and Henley.

What would fix it

Keep the weekly London anchor, Farmoor measured-flow context and exact Tilford history fresh; obtain a approved naturalised Farmoor flow history and a public or supplier-approved Theale flow replacement; obtain the older BGS Stonor series; and add demand, groundwater source performance, transfers, asset availability and treatment headroom before repeating frozen local validation.

UUXUnited UtilitiesPartly covered

Available now

Strategic supply area: current supplier Regional Total with passing 30-, 60- and 90-day north-west regional reservoir forecasts, plus research-only weekly source-group context for Haweswater and Thirlmere, Pennine Sources and Dee and Vyrnwy. A separate Carlisle row is also ingested as current context.

Not covered

Definition-exact Haweswater, Dee and Castle Carrock trigger histories; groundwater, river, transfer, demand and operating components in the Strategic supply area; North Eden combined annual borehole-licence usage; and Barepot's exact River Derwent decision-flow series.

Why

All five weekly public reservoir rows are now ingested, but the supplier's live definitions are broader than the governing drought-plan triggers: Haweswater is combined with Thirlmere, the Dee group is combined with Vyrnwy and the Carlisle row is not stated to be Castle Carrock-only. The public archive begins in 2026, North Eden licence usage is not published and the plan does not identify a public Barepot gauge/measure. The draft 2027 Pennines level is not yet in force.

What would fix it

Obtain definition-consistent histories for Haweswater, Celyn/Brenig and Castle Carrock; secure North Eden cumulative abstraction and the exact Barepot flow series; then add demand, transfer, asset-availability and treatment-headroom histories and repeat event and quiet-period validation.

WXWWessex WaterPartly covered

Available now

Single Wessex supply area: current Woodyates groundwater seasonal position with a passing 30-day forecasts, plus a separately checksd Clatworthy 30-day reservoir component when its monthly target is current.

Not covered

The integrated Wessex resource position across other groundwater sources, reservoirs, rivers, transfers, demand and operating constraints.

Why

Woodyates and Clatworthy are separately scoped components, not a supplier-approved integrated index. Clatworthy's 60- and 90-day checks fail, the wider reservoir feed is scheduled for March 2027 and public covering the same dates river, transfer, demand and operating histories remain incomplete.

What would fix it

Use the announced March 2027 feed, or secure earlier supplier API access, then combine its fields with Woodyates and approved river, transfer, demand and operating indicators and repeat frozen validation before claiming a complete zone baseline.

Smaller local water companies

Some new developments use a different supplier.

Nine smaller water companies reported in England in 2025. We have a mapped boundary for only one of them. Until the other site boundaries are public, an address inside those developments may show the surrounding main supplier.

See the DWI 2025 company list ↗

ALB

Albion WaterExact site boundary not yet available

ALE

Albion EcoExact site boundary not yet available

ESP

ESP WaterExact site boundary not yet available

ICW

Icosa WaterExact site boundary not yet available

IWN

Independent Water NetworksExact site boundary not yet available

LNW

Leep Networks (Water)Exact site boundary not yet available

MTX

Matrix WaterExact site boundary not yet available

MUA

MUA WaterExact site boundary not yet available

VWP

Veolia Water ProjectsOne supply area mapped; other sites may be missing

Wales and Scotland

Wales is mapped. Scotland has a broad national update.

All 23 Dŵr Cymru areas are mapped. Scottish Water publishes national and four regional water-level updates, but not the detailed local boundaries we would need for postcode forecasts.

DCW

Dŵr Cymru Welsh Water

23 published resource zones · regional model pending

HDD

Hafren Dyfrdwy

4 published resource zones · regional model pending

SCT

Scottish Water resource reporting

National reservoir storage 81% · four broad regional readings available; local customer boundaries are not yet available

Scottish Water source ↗

What remains

Two complete. Eleven partial. Four external data blockers.

We have used every reliable free public source we found. The list above says exactly what is missing for the remaining companies. New data will be used only after it passes the same accuracy checks.

Explore the map How forecasts are checked