Thames Water Utilities Ltd, known as Thames Water, is the private utility company responsible for the public water supply and waste water treatment in large parts of Greater London, the Thames Valley, Surrey, Gloucestershire, Wiltshire, Kent, and some other areas of in the United Kingdom.

Thames Water is the UK's largest water and wastewater services company, and is owned by Kemble Water Limited.

It includes, at Beckton, both Europe's largest wastewater treatment works and the UK's first large-scale Desalination Plant.

Thames Water is regulated under the Water Industry Act 1991.

Thames Water is responsible for some of the largest civil engineering programmes in Europe, including the £2.2 billion London Tideway Tunnels, the Thames Water Ring Main around London and the proposed reservoir at Abingdon, Oxfordshire, which would be the largest enclosed reservoir in the UK.

Source: Wikipedia