Southern Water supplies most of Southampton (99.9% of its postcodes), and the quality of that water is regulated by the Drinking Water Inspectorate in England and Wales, per ONS Postcode Directory (May 2026), each postcode placed in the water companies' supply-area boundaries (read 26 September 2026).
Source: ONS Postcode Directory (May 2026), each postcode placed in the water companies' supply-area boundaries — read 26 September 2026Contains OS data © Crown copyright and database right 2026Contains Royal Mail data © Royal Mail copyright and database right 2026Source: Office for National Statistics licensed under the Open Government Licence v.3.0Water company boundaries © Water UK, licensed under CC BY 4.0
Drinking Water Inspectorate (DWI) enforces the UK drinking water quality regulations in England and Wales. Figures it classifies or regulates on this page cover England and Wales only.
The official answer
Southampton is supplied by Southern Water, whose water is regulated by Drinking Water Inspectorate under the UK drinking water quality regulations.
Source: ONS Postcode Directory (May 2026), each postcode placed in the water companies' supply-area boundaries — read 26 September 2026Contains OS data © Crown copyright and database right 2026Contains Royal Mail data © Royal Mail copyright and database right 2026Source: Office for National Statistics licensed under the Open Government Licence v.3.0Water company boundaries © Water UK, licensed under CC BY 4.0
Who supplies Southampton
Southern Water's supply area (99.9% of the 5,806 live postcodes in Southampton): 5805 postcodes
Source: ONS Postcode Directory (May 2026), each postcode placed in the water companies' supply-area boundaries — read 26 September 2026Contains OS data © Crown copyright and database right 2026Contains Royal Mail data © Royal Mail copyright and database right 2026Source: Office for National Statistics licensed under the Open Government Licence v.3.0Water company boundaries © Water UK, licensed under CC BY 4.0
Not placed in any regional water company's supply area (under 0.1% of the 5,806 live postcodes in Southampton): 1 postcodes
Source: ONS Postcode Directory (May 2026), each postcode placed in the water companies' supply-area boundaries — read 26 September 2026Contains OS data © Crown copyright and database right 2026Contains Royal Mail data © Royal Mail copyright and database right 2026Source: Office for National Statistics licensed under the Open Government Licence v.3.0Water company boundaries © Water UK, licensed under CC BY 4.0
What Southern Water's own figures show
Southern Water's published drinking water quality results for 2024: 64442 published sample results
Source: Southern Water's published drinking water quality results for 2024, published on the water industry's shared data portal — dated 20 September 2026, read 20 September 2026Southern Water Domestic Drinking Water Quality 2024 by Southern Water Limited is licensed under CC BY 4.0
Southern Water's published drinking water quality results for 2025: 32184 published sample results
Source: Southern Water's published drinking water quality results for 2025, published on the water industry's shared data portal — dated 20 September 2026, read 20 September 2026Southern Water Domestic Drinking Water Quality 2025 by Southern Water Limited is licensed under CC BY 4.0
Southern Water's published drinking water quality results: 181370 published sample results
Source: Southern Water's published drinking water quality results, published on the water industry's shared data portal — dated 20 September 2026, read 20 September 2026Southern Water Domestic Water Quality by Southern Water Limited is licensed under CC BY 4.0
Southern Water's published drinking water quality results for 2021: 57915 published sample results
Source: Southern Water's published drinking water quality results for 2021, published on the water industry's shared data portal — dated 20 September 2026, read 20 September 2026Southern Water domestic water quality 2021 by Southern Water Limited is licensed under CC BY 4.0
Southern Water's published drinking water quality results for 2022: 60847 published sample results
Source: Southern Water's published drinking water quality results for 2022, published on the water industry's shared data portal — dated 20 September 2026, read 20 September 2026Southern Water domestic water quality 2022 by Southern Water Limited is licensed under CC BY 4.0
Southern Water's published drinking water quality results for 2023: 62608 published sample results
Source: Southern Water's published drinking water quality results for 2023, published on the water industry's shared data portal — dated 20 September 2026, read 20 September 2026Southern Water domestic water quality 2023 by Southern Water Limited is licensed under CC BY 4.0
Southern Water's published drinking water quality results for 2016 to 2018, part 1: 299467 published sample results
Source: Southern Water's published drinking water quality results for 2016 to 2018, part 1, published on the water industry's shared data portal — dated 20 September 2026, read 20 September 2026Southern Water Domestic Drinking Water Quality 2016_2018_part1 by Southern Water Limited is licensed under CC BY 4.0
Southern Water's published drinking water quality results for 2018 to 2022, part 1: 853785 published sample results
Source: Southern Water's published drinking water quality results for 2018 to 2022, part 1, published on the water industry's shared data portal — dated 20 September 2026, read 20 September 2026Southern Water Domestic Drinking Water Quality 2018_2022_part1 by Southern Water Limited is licensed under CC BY 4.0
Southern Water's published drinking water quality results for 2022 to 2026, part 1: 1000000 published sample results
Source: Southern Water's published drinking water quality results for 2022 to 2026, part 1, published on the water industry's shared data portal — dated 20 September 2026, read 20 September 2026Southern Water Drinking Water Quality 2022_2026_part1 by Southern Water Limited is licensed under CC BY 4.0
Southern Water's published drinking water quality results for 2022 to 2026, part 2: 313798 published sample results
Source: Southern Water's published drinking water quality results for 2022 to 2026, part 2, published on the water industry's shared data portal — dated 20 September 2026, read 20 September 2026Southern Water Domestic Drinking Water Quality 2022_2026_part2 by Southern Water Limited is licensed under CC BY 4.0
What an independent test shows
We have not tested Southampton’s water ourselves. Nothing on this page is our own measurement. You can have your own supply tested.
Related pages
- What we hold on tap-water safety, town by town
- Hard water in the UK
- Check your postcode
- Every zone we hold a figure for
- Southern Water: what we hold
- Southern Water hosepipe ban status
- What Southern Water publishes for your postcode
- UK water companies
- Southampton, Massachusetts
- Southampton, New Jersey
- Southampton, New York
- Southampton, Pennsylvania