🇬🇧 Sector Guide · UK Water Industry Structure
Water Utilities UK — Complete Guide to UK Water Companies, Regulation and AMP8
The UK water sector is one of the most regulated private utilities in the world. Understanding which companies operate where, how Ofwat sets their investment obligations and how AMP8 is reshaping the supply chain is essential for anyone doing business in the sector. This guide covers the complete picture.
📅 Updated July 2026
⏱ 9 min read
✍️ Water Industry Hub Intelligence
17
Water & sewerage companies in England & Wales
£96bn
AMP8 investment committed 2025–2030
Ofwat
Economic regulator for England & Wales
7,845+
Verified WIH supply chain suppliers
How the UK Water Sector Is Structured
The water industry in the UK is not a single national utility — it is a set of regionally licensed monopolies, each responsible for water supply, wastewater collection and treatment, or both, within a defined geographic area. The structure differs across the four nations:
- England and Wales: Privatised in 1989. Water and sewerage services are provided by private companies operating under licences granted by Ofwat. There are 17 licensed water and sewerage companies (WaSCs) and water-only companies (WoCs), regulated by Ofwat, the Drinking Water Inspectorate (DWI) and the Environment Agency.
- Scotland: Scottish Water is a publicly owned statutory corporation, reporting to the Scottish Government. It provides water and sewerage services across the whole of Scotland and is regulated by the Water Industry Commission for Scotland (WICS) and SEPA.
- Northern Ireland: Northern Ireland Water is a government-owned company providing water and sewerage services across Northern Ireland, regulated by the Utility Regulator.
Important note
Water utilities are regional monopolies — customers cannot choose their water company. Supply areas are fixed by licence. The information below relates to licensed supply areas as at July 2026; contact individual companies or Ofwat for current boundary information.
Water and Sewerage Companies in England and Wales
The following companies hold Ofwat licences for water and sewerage (WaSCs) or water-only (WoCs) services in England and Wales. WIH operator pages provide further detail on each company's procurement approach, frameworks and supply chain requirements.
Water and Sewerage Companies (WaSCs)
Water & Sewerage
Thames Water
London, Thames Valley, parts of the South East and Home Counties. The largest water company in the UK by customer numbers.
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Water & Sewerage
Severn Trent Water
Midlands and parts of mid-Wales. Serves approximately eight million customers across a large inland geography.
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Water & Sewerage
United Utilities
North West England — Greater Manchester, Lancashire, Cumbria, Merseyside and Cheshire. Largest water and wastewater company in the North West.
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Water & Sewerage
Anglian Water
East of England — from the Humber to the Thames Estuary, including Lincolnshire, East Anglia and parts of Northamptonshire. The driest region in the country, making water resource management a strategic priority.
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Water & Sewerage
Yorkshire Water
Yorkshire — serving approximately five million customers across the county, including major urban centres of Leeds, Sheffield, Bradford and Hull.
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Water & Sewerage
Wessex Water
South West England — Bristol, Wiltshire, Dorset and parts of Somerset and Hampshire.
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Water & Sewerage
South West Water
Devon, Cornwall and parts of Somerset and Dorset. Also supplies Bristol Water customers following the acquisition of Bristol Water in 2023.
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Water & Sewerage
Dŵr Cymru Welsh Water
Most of Wales and parts of the English border counties. A not-for-profit company — unique among the privatised WaSCs in having no shareholders.
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Water & Sewerage
Northumbrian Water
North East England — County Durham, Tyne and Wear, Northumberland and Tees Valley. Also operates Essex & Suffolk Water in the South East.
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Water & Sewerage
Southern Water
Kent, Sussex, Hampshire and the Isle of Wight. The company has faced significant regulatory scrutiny in recent years over environmental compliance.
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Water-Only Companies (WoCs)
Water Only
Affinity Water
Hertfordshire, Bedfordshire, Buckinghamshire, Essex, Kent and Surrey. The largest water-only company in the UK.
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Water Only
South East Water
Kent, Sussex, Hampshire, Surrey and Berkshire. Serves around 2.1 million customers in the South East.
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Water Only
South Staffs Water
South Staffordshire and parts of Lincolnshire (via Cambridge Water, a subsidiary).
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Water Only
SES Water
Surrey and parts of West Sussex and Kent — a smaller water-only company serving around 750,000 people in the Home Counties.
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Water Only
Portsmouth Water
Portsmouth, Havant, parts of Hampshire and West Sussex. A long-established water-only company with a strong track record on leakage performance.
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Water Only
Bournemouth Water
Bournemouth, Christchurch and parts of Dorset and Hampshire. Operated as part of the South West Water group (Pennon Group).
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Water Only
Sutton and East Surrey Water
Parts of Surrey, West Sussex and Greater London. Now trading as SES Water following a rebrand.
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Scotland and Northern Ireland
Water & Sewerage · Public
Scottish Water
All of Scotland. The sole water and sewerage provider, publicly owned by the Scottish Government. Regulated by WICS and SEPA. Operates the Scottish Water Business Stream retail subsidiary for commercial customers.
Water & Sewerage · Public
Northern Ireland Water
All of Northern Ireland. A government-owned company providing both water and sewerage services. Regulated by the Utility Regulator. Operates under a distinct legislative framework from Great Britain.
How Regulation Works — Ofwat and the Price Review
Ofwat — the Water Services Regulation Authority — is the economic regulator for water and wastewater services in England and Wales. Its primary role is to set the price limits within which companies can operate, ensure efficient delivery of services and protect the long-term interests of customers.
Ofwat sets prices through a periodic Price Review every five years. The current period is AMP8 (Asset Management Period 8), covering 2025 to 2030. Companies submit Business Plans to Ofwat setting out their proposed investment programmes, cost base and performance commitments. Ofwat scrutinises these plans, challenges inefficiency, and sets Final Determinations that include allowed revenue, capital expenditure and Outcome Delivery Incentives (ODIs) — financial rewards for outperformance and penalties for failure on key metrics.
AMP8 — what it means for the supply chain
The AMP8 Final Determinations committed the 17 water and sewerage companies to approximately £96 billion of total expenditure between 2025 and 2030 — the largest regulated investment programme in UK water sector history. This translates directly into capital delivery contracts, framework call-offs, and operational expenditure across the sector's supply chain. For companies seeking to win work in the water sector, understanding each utility's AMP8 programme is essential.
Key Regulators at a Glance
Ofwat
Economic regulator for England and Wales. Sets price limits, monitors performance and enforces licence conditions. Five-year Price Reviews set the framework for capital investment.
Environment Agency / Natural Resources Wales
Environmental regulators for England and Wales respectively. Set discharge consents for treatment works, regulate abstraction licences and enforce compliance with environmental legislation.
Drinking Water Inspectorate (DWI)
Regulates the quality of drinking water in England and Wales. Audits compliance with the Water Supply (Water Quality) Regulations and investigates failures in drinking water quality.
WICS
Water Industry Commission for Scotland — economic regulator for Scottish Water, setting the Strategic Review of Charges every six years.
SEPA
Scottish Environment Protection Agency — environmental regulator for Scotland, including water quality and abstraction regulation.
Utility Regulator (NI)
Regulates Northern Ireland Water on both price and quality of service.
Explore WIH's Operator Pages and Supplier Directory
In-depth profiles of every major UK water utility — plus 7,845+ verified supply chain suppliers covering every discipline in the water sector.
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Water Industry Hub® is an independent intelligence platform for the UK water sector. Company supply area descriptions are indicative — for definitive boundary information consult Ofwat or the individual company. Ownership structures and corporate arrangements are subject to change. Updated July 2026.